Restoring The Landscape With Native Plants

Beneficial Insect Profile - Lacewings

noreply@blogger.com (Heather Holm) — Fri, 24 Oct 2014 15:29:00 +0000

Brown lacewing larva

As the last remaining leaves fall from the trees, I start to think about all the beneficial insects that are seeking shelter under the leaf litter or attached to plant stems for the winter. With leaf blowers dominating the suburban landscape, many gardeners are perhaps not aware that they are eliminating next season's predators and parasitoids when they clean-up their garden in the fall. Eggs, larvae, pupae and adults of beneficial insects are blown or raked up, bagged with the leaves and set out at the curb.

In perennial gardens we don't need to be this fastidious. Leaves, plant debris, and flower stems equal insulation and nesting sites, including nesting sites for cavity-nesting bees and solitary wasps. If you grow apple trees then yes, cleanliness is important so the leaf litter under the trees does not harbor pest populations or fungi such as apple scab.

Green lacewing larva

Lacewings are fascinating insects that belong to the Chyrsopidae and Hemerobiidae families in the insect order Neuroptera. They have been long been recognized for their importance in the control of small or soft-bodied insects such as aphids, thrips, mites, and whiteflies. The larvae of lacewings are voracious predators and have been given several nicknames including 'aphid lions'.

Adult green lacewing feeding
on pollen on Sprengel's sedge

Adult lacewing females lay eggs on the underside of leaves, often where the pest population occurs. Brown lacewings lay their eggs directly onto leaves, green lacewing eggs are suspended from the leaf by long, thread-like stalks. When the larvae hatch, they begin consuming their prey at an impressive rate - up to 400 aphids per week (source: Farming with Native Beneficial Insects).

Adult lacewings feed on pollen and nectar from a variety of plants including forbs and sedges; they also feed on the honeydew created by aphids.

Close up of brown lacewing larva

There are multiple generations of lacewings throughout the growing season in our gardens. The larvae spin cocoons when ready to pupate; these cocoons are attached to leaves or plant stems. Lacewings overwinter in these cocoons; the leaves drop to the ground from perennial foliage in fall and the cocoon remains protected from winter temperatures in the layers of leaf litter. Lacewings can also overwinter as adults and seek shelter under the leaf litter or in another protected site such as behind a loose piece of tree bark. During the growing season, if you have a plant being afflicted by aphids, turn over the leaves and look for lacewing eggs or larvae.

Lacewings are just one of many beneficial insects that need plant debris and leaves left in the garden. Cut down your perennial garden in late spring leaving 12-15" of perennial stem stubble (for cavity-nesting bees). Keep the debris instead of bagging it and use it as a natural mulch (combined with leaves) by laying it on the ground among the emerging perennial plants. The perennials will cover the debris in no time as their new leaves emerge and flower stalks form.

Ground-Nesting Bee Profile ~ Unequal Cellophane Bee, Colletes inaequalis

noreply@blogger.com (Heather Holm) — Thu, 22 May 2014 16:16:00 +0000

The Unequal Cellophane Bee is typically the earliest Colletes species to emerge in the spring in our area. This spring, I found several aggregations of nests on south-facing slopes at a local park.

Females began excavating nests as early as the third week of April (unseasonably cool spring). Other nests not on the exposed slopes were easy to find due to the prairie burn performed the previous fall. Ant nests clustered around the clumps of little bluestem grass, Schizachyrium scoparium in this prairie were dug/sought out by northern flickers in early April. The flickers did not show any interest in the cellophane bee nests.

The cellophane bee nests, besides those in aggregations on the exposed, sandy slope were scattered throughout the flat, open area of the burned portion of the prairie. In late April, on cool days, many females flew low to the ground perhaps searching for new nesting sites or orienting themselves to an existing nest.

Bee flies were active near the bee nesting sites
resting on the ground

Bee flies were also seen near the nesting sites when the nests were being excavated.

During the first week of May when temperatures reached 70 F, there was an increase in nest excavation activity, especially in the sites on the exposed south-facing slopes where soil temperatures were likely warmer.

Cellophane bees secrete a polyester-like substance from their Dufour's gland. This gland secretion is spread over the soil in their brood cells with their tongue. The lining helps protect the larval provisions from bacteria and fungi and because the provisions are liquidy, it helps keep the provisions from leaking out of the brood cell. Unlike many other bee species, instead of the egg being laid on the provisions, these cellophane bees lay the egg suspended above the provisions in the brood cell.

Females were shy and would back
down the nest entrances a few inches but if you waited
long enough, they would come closer to the surface.

Along with the Dufuour's gland secretion, several species of cellophane bees have mandibular gland secretions believed to act as a pheromone to attract a mate, mark food sources and mark male territories. The mandibular gland secretion has a strong citrus odor.

Aggregation of nests on sandy slope

They have one generation per year (univoltine). Males usually emerge first, digging their own exit burrows vertically from their brood cells followed by the females.

Nest Tumulus

When these cellophane bees first emerged there were no plants flowering in the area. Batra (1980) observed these cellophane bees foraging on red maple, Acer rubrum flowers.

Female in Eastern Red Cedar tree

Many females were flying close to or landing on Eastern red cedar, Juniperus virginiana trees, to perhaps warm themselves in the unseasonably cool temperatures but were also observed there a few weeks later after the willows had begun flowering (above). Batra (1980), also observed swarms of these bees around a small pine tree and it was thought that the mandibular gland secretion by the males may have been applied to the pine to attract females for mating.

Willows were the first observed plant that these cellophane bees, both male and female foraged on in the park this spring. Copulation took place while the females foraged on willow flowers.

References:
Batra, S. W. T. (1980). Ecology, behavior, pheromones, parasites and management of the sympatric vernal bees Colletes inaequalis, C. thoracicus and C. validus. Journal of the Kansas Entomological Society, 509-538.

Native Bee Spotlight: Cuckoo Bees ~ Coelioxys spp.

noreply@blogger.com (Heather Holm) — Mon, 03 Feb 2014 21:35:00 +0000

Cuckoo Bees ~ Coelioxys spp.

A female cuckoo bee, Coelioxys sp. nectars on
hairy false goldenaster, Heterotheca villosa in late fall

There are many types of cuckoo bees in North America. In the Coelioxys genus, there are approximately 46 speces. The common name "cuckoo bee" is typically used for any bee species that lays its eggs in the nests of other bees. These bees are known as cleptoparasites, where the cuckoo bee larvae kill the host larvae and feed on the provisions (pollen and nectar) provided by the host bee.

Coelioxys cuckoo bees are common in the summer months; in central Minnesota I typically see them from June until October. Both males and females can be observed visiting flowers for nectar and females looking for, or waiting to enter a host's nest. These cuckoo bees lay their eggs in the nests of leafcutter bees, Megachile spp. Less frequently, they have been documented laying eggs in the nests of Anthophora, Centris and Euglossa spp.

A female cuckoo bee watches for the
female leafcutter bee to exit the nest
in the rock cavity.

The cuckoo bee flies closer to the entrance
anticipating the exit of the host bee.

Females Coelioxys bees actively look for a host's nest. Once a nest is found, the female cuckoo bee waits until the host bee leaves the nest to collect provisions. With a short window of opportunity, the cuckoo bee slips in the empty nest and looks for a fully provisioned brood cell to lay its eggs in.

The host leafcutter bee, Megachile sp. enters the nest in the
rock cavity carrying a piece of leaf to line or cap the brood cell.

Females have a sharply tapered or triangular-shaped abdomen. This acute point on the end of the abdomen is used to pierce through the layers of leaf pieces that line the brood cells of their host, leafcutter bees. The egg(s) is laid within the layers of leaves, or underneath the pollen mass hidden from sight in case the host leafcutter bee is still in the process of provisioning the nest. The cuckoo bee eggs are often different in size or appearance which may be another reason why the cuckoo bee hides the eggs.

The large sickle-like mandibles that the cuckoo bee larvae use to kill its siblings and host larva.
Illustration from: Michener, C. D. (2000). The bees of the world (Vol. 1). JHU Press.

The menacing part of this cleptoparasitic life cycle occurs after the cuckoo bee larva has hatched and begins to develop. The larva develops large sickle-shaped mandibles that are directed forward (instead of downward) to prepare to kill the host egg or young host larva. By the third or fourth instar, the Coelioxys larva has killed any sibling larvae and the host. It now has an empty brood cell stocked with pollen and nectar provisions to feed on and develop.

A female cuckoo bee nectars on
purple prairie clover, Dalea purpurea

The timing of adult emergence of cuckoo bees is very critical; there is a short window of opportunity to overlap the timing of the host's adult emergence. Coelioxys spp. have been documented emerging slightly earlier or around the same time as their host. A larvae will often develop into an adult the same year as the nest is constructed and more female cuckoo bees are produced earlier in the season.

A female cuckoo bee perches on foliage low to the ground
watching for a leafcutter bee to emerge from a nest in the ground.

Appearance:
Female: Tapered abdomen ending in an acute point
Male: Pronged or multi-spined abdomen
Both Male & Female: Hairs on the bottom of the eyes
Relatively hairless, dark gray - black, often pocked appearance
Many species have red legs

Native plants I have observed Coelioxys spp. foraging on:
Butterfly milkweed, Asclepias tuberosa
Wild Bergamot, Monarda fistulosa
Prairie Coreopsis, Coreopsis palmata
Hoary Vervain, Verbena stricta
Joe Pye Weed, Eutrochium maculatum Smooth Oxeye, Heliopsis helianthoides Black-Eyed Susan, Rudbeckia hirta
New England Aster, Symphyotrichum novae-angliae
Hairy False Goldenaster, Heterotheca villosa
Purple Prairie Clover, Dalea purpurea

References:
Baker, J. R. (1971). Development and sexual dimorphism of larvae of the bee genus Coelioxys. Journal of the Kansas Entomological Society, 225-235.

Michener, C. D. (2000). The bees of the world (Vol. 1). JHU Press.

Rozen Jr, J. G., & Kamel, S. M. (2006). Interspecific variation in immature larvae of the cleptoparasitic bee genus Coelioxys (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society, 79(4), 348-358.

Scott, V. L., Kelley, S. T., & Strickler, K. (2000). Reproductive biology of two Coelioxys cleptoparasites in relation to their Megachile hosts (Hymenoptera: Megachilidae). Annals of the Entomological Society of America, 93(4), 941-948.

Book Release: Pollinators of Native Plants

noreply@blogger.com (Heather Holm) — Fri, 10 Jan 2014 14:54:00 +0000

Available March 2014

Book Website: www.pollinatorsnativeplants.com

Attract and Support Pollinators with Native Plants
• Over 65 perennial native plants of the Midwest, Great Lakes region, Northeast and southern Canada profiled
• Pollinators, beneficial insects and flower visitors featured that the native plants attract
• 1600+ photos of native plants, pollinators and beneficial insects
• Attract, observe and identify pollinators on native plants
• Informational chapters on pollination, types of pollinators and beneficial insects, pollinator habitat and conservation
• Native plant chapters including prairie, woodland edge and wetland edge
• Sample pollinator landscape plans including site-specific and pollinator-specific plans

The book underscores the pivotal role that native plants play in supporting pollinators and beneficial insects.

Paperback with full-color interior, photographs and illustrations throughout
6” x 9”, 320 pp., ISBN 9780991356300

Predator Profile ~ Grass Carrying Wasps, Isodontia spp.

noreply@blogger.com (Heather Holm) — Thu, 12 Dec 2013 16:15:00 +0000

Grass-Carrying Wasps ~ Isodontia spp.

There are a number of ways to attract beneficial insects to your landscape. Planting a diversity of native plants is an easy, win-win solution. Not only do the plants attract many types of beneficial insects including solitary wasps, but they help support a functioning, complex ecosystem.

One of the most interesting solitary wasps in my landscape is the grass carrying wasp. Several years ago I purchased a bell-shaped wire frame. I filled the openings with hollow stems from native perennials in my yard to see what types of solitary bees would use the cavities. I was surprised to find that the primary insect that uses these cavities is the grass carrying wasp, a welcome resident.

Grass-carrying wasps are predators of crickets and katydids. Females sting their prey in the head or thorax which causes paralysis. The immobile prey is carried back to the nest located in cavities in hollow stems, holes bored in wood or openings in rocks. Prey, alive but immobile is stocked in the nest. When enough prey is cached the female wasp lays an egg in the cavity near the prey. Prey becomes food for the developing wasp larvae to feed upon. Females collect grass pieces carrying strands clasped in their mandibles. In my landscape, I have observed them picking up pieces of little bluestem, Schizachyrium scoparium grass blades.

Little bluestem on my 'prairie' slope.
Grass-carrying wasps use the grass blades in their nests.

They use these pieces of grass to divide their nesting cavity into sections as well as close the cavity. Look for pieces of grass stuffed into the ends of the board holes.

Grass carrying wasps are medium-sized thread-waisted wasps with a black head, thorax and abdomen. Their wings are medium to light brown. Similar to the majority of solitary wasps they are very docile and not aggressive towards humans - even near their nest.

These wasps visit a number of native perennials to feed on nectar. They perennials include common boneset, Eupatorium perfoliatum, pale Indian plantain, Arnoglossum atriplicifolium, rattlesnake master, Eryngium yuccifolium, stiff goldenrod, Solidago rigida and mountain mint, Pycnanthemum virginianum.

Remember to leave plant stems and grass blades standing throughout the winter and into late spring. Insects are using the stems as overwintering sites and inside the cavities could be pupae of solitary bees and beneficial insects. Carefully cut the stems in large pieces and lay them on the ground to allow insects to emerge. Grass blades left on the ground once cut will be used by birds as nesting materials or by these grass carrying wasps.

Beneficial Insects - Predators

noreply@blogger.com (Heather Holm) — Fri, 25 Oct 2013 15:10:00 +0000

Beneficial insects (natural enemies) are predators and parasitoids; they maintain the checks and balances of the insect world, helping to prevent pest populations from getting out of control and causing damage to crops and garden plants. Many of these beneficial insects rely on floral rewards (pollen and nectar) for food so they can be fostered and attracted with a healthy, diverse native planting.

Ladybird Beetle Larva
Feeding on an Aphid

These predators and parasitoids hunt and feed on prey in either or both the adult and larval forms. Soldier beetles, lady bird beetles, syrphid flies, solitary wasps, crab spiders and minute pirate bugs are some important beneficial insects.

The abundance and diversity of beneficial insects in a particular landscape depends on:

the diversity of the landscape
the quality and abundance of forage plants
the availability of prey
the number and quality of nesting sites
the overall health of the plant community

Native plants play a key role in attracting beneficial insects (and more pollinators). Beneficial insects feed on floral resources and seek shelter in the foliage when not hunting or parasitizing prey. A stressed plant, including one poorly situated, is more susceptible to pests. When selecting plants, make sure to match the site with the habitat where the native plant occurs naturally.

Predators
Predators feed on insects as adults and/or as larvae. Solitary wasps are excellent predators of large prey; prey, once caught, are cached in the nest live for the hatched larvae to feed on and fuel development. They help control caterpillars, sawfly larvae, katydids, crickets, and grasshoppers - all insects that feed on foliage.

Predator Profile - Great Golden Digger Wasp, Sphex ichneumoneus

Nest Excavation - The female excavates clumps of soil and
holding the clumps between her mandibles
and forelegs, backs out of the nest and deposits
the soil away from the nest entrance.

Great golden digger wasps are solitary wasps that nest in the ground. These large, brightly colored wasps are prey on crickets and katydids.

Nests are excavated in sand or gravelly soil. Females can be observed excavating nests in mid-summer, pictured on the left excavating a nest in mid-July this year.

Females paralyze prey and fly it back to the nest grasping the prey with their legs and holding it underneath them (left). The wasp places the prey on the ground near the nest entrance. She then checks the nest before placing the prey inside. Females often drag the prey backwards into the nest hole grasping it with her mandibles. Once the prey is cached, a single egg is laid on each cricket/katydid. When the larva hatches, it begins feeding on the prey until pupation.

These wasps are common in late summer and visit a variety of native plants that offer nectar like culver’s root, (Veronicastrum virginicum), rattlesnake master (Eryngium yuccifolium), purple prairie clover (Dalea purpurea) and spotted beebalm (Monarda punctata) (left).

Providing native plants for nectar foraging helps support these solitary wasps and fuel their hunting activities. A diverse native plant community also provides cover for their prey.

Predator Profile - Syrphid Flies, Family Syrphidae
Syrphid flies are active from spring through late fall and visit a large variety of native plants where they can access floral resources, typically in less complex flower forms.

Adult syrphid flies visit flowers to feed on both pollen and nectar. Females foraging for pollen often hold the flower's anthers with their forelegs while they sponge up the protein-rich pollen with their mouthparts.

Many syrphid flies are excellent mimics and are often mistaken for bees or wasps as their coloration and behavior mimics bees and wasps (left). This mimicry helps protect them from predation by birds and other predators.

Larvae look like small caterpillars and feed on aphids or other small, soft-bodied insects (left). Look for the larvae on the underside of leaves where there is a large aphid population. They often feed on aphids that are much larger than themselves.

Pesticides have a serious impact on beneficial insect (and pollinator) populations. If insecticides are applied to control a problem pest, the beneficial insect population is eliminated at the same time. It often takes less time for the pest population to recover from an application than it does for the beneficial insect populations to recover. Continous pesticide use can result in the ongoing imbalance of pest and beneficial insect populations.

A Pollinator's View: Flower Attractants

noreply@blogger.com (Heather Holm) — Wed, 18 Sep 2013 15:37:00 +0000

Nectar Guides

Prairie Phlox, Phlox pilosa
Dark pink lines near the corolla opening
act as nectar guides for pollinators.

Nectar guides are stripes or spots inside the flower corolla that guide the insect visitor past the anthers to the nectar reward. Since bees have compound eyes with receptors that can discern different wavelengths from the human eye, some guides on flowers are not visible to humans. Bees have the ability to see intensity, color and polarization of light. They also have a high sensitivity to UV and red-blindness on the other end of the color spectrum. Because their perception of flower color is different from humans, many floral visual cues such as nectar guides and color contrasts in flowers are visible only to bees.

Black-eyed Susan flowers, Rudbeckia hirta, look a lot different to bees than humans. The central disc florets on the cones along with the bases of the ray florets absorb ultraviolet light. The outer tips of the ray florets reflect ultraviolet light.

Illustration approximating the
bee's view of the flower rays
absorbing and reflecting
ultraviolet light.

The overall appearance to bees is two rings, light and dark from the outer ray floret tips towards the central disc florets. The differences in color of the outer and inner rays are believed to act as nectar guides for visiting bees. These potentially help guide and orient pollinators towards the floral rewards (food).

Flower Color & Color Change

Heptica flower buds
are often a different
color than the sepals,
and once open, flower
color changes as it
develops.

On many plants, the flower color changes from the beginning to the end of the flowering period. These color changes can coincide with the flower phase, male or female, the depletion of the flower rewards or indicate that the flower has been pollinated. Changes in flower color can redirect flower visitors to other flowers that are still offering a reward. Lighter flower colors, whites, creams and yellows, have the advantage of being more visible to nocturnal pollinators. Bees have shown a preference for flowers that are pink, purple or blue, their second choice white or yellow flowers (as the colors appear to humans).

Flower Shape & Color Contrast

The shape of a flower can influence the types of floral visitors it attracts. Bees like symmetrical flowers, with simple outlines. They also like a landing pad, such as the bottom lip of bilabiate flower.

Color contrast between more than one color on the corolla, or between the color of the anthers and petals also serves as an attractant to flower visitors.

New England aster, Symphyotrichum novae-angliae (left), has contrasting lavender rays and yellow-orange disc florets in the center. The open, flat-topped flowers are any easy landing pad for bees, flies, beetles and butterflies.

References:
McCrea, K. D., & Levy, M. (1983). Photographic visualization of floral colors as perceived by honeybee pollinators. American journal of botany, 369-375.

Willmer, P. (2011). Pollination and floral ecology. Princeton University Press.

Pollination of Wild White Indigo ~ Baptisia lactea

noreply@blogger.com (Heather Holm) — Wed, 07 Aug 2013 15:58:00 +0000

Wild White Indigo ~ Baptisia lactea (B. alba)

The tall racemes of wild white indigo project above the other prairie forbs and grasses in early spring before these competing plants start to grow. It is statuesque in form, with the blue-gray foliage and light gray, sturdy stems. If you purchase or grow wild white indigo, small seedlings can take a few years to establish before flowering.

Wild white indigo plants grow in open, mesic prairies in full sun.

Worker and queen bumble bees are the primary pollinators of wild white indigo. Their size and strength allows them to pry open the flowers accessing the nectar inside. In a cool spring where the flowers open later than average, more queen visits occur. In an average season, the flowers are visited by more worker bumble bees than queens.

The flowers of wild white indigo are protandrous - the male reproductive organs develop before the female reproductive organs. Flowers open and mature from the bottom upwards on the raceme.

Bumble bees fly towards the upright flower raceme landing on one of the lower flowers in the pistillate (female) phase which typically produce more nectar than those at the top in the staminate (male) phase.

After bumble bees seek out the higher nectar rewards on the pistillate flowers, they work their way up the flower raceme to the upper flowers in the staminate (male) phase. Pollen is therefore transferred during the last stage of their visit on staminate (male) flowers. The bumble bees move on to a new flower raceme carrying pollen with them to pollinate the next staminate (female) flower visited.

A smaller worker bumble bee pries open a staminate (male) flower. Remaining in this position for close to a minute, it rubs its rear legs over the exposed stamens collecting pollen.

Once the flowers are pollinated, an inflated seed pod develops housing the seeds, turning from light green to dark gray over the summer.

The seeds of wild white indigo are heavily predated on by a small weevil, Trichapion rostrum (Apion rostrum). This weevil can be very destructive, consuming most or all of the developing seeds inside a seed pod. Female weevils seek out the pods in June and drill a small hole at the base. Eggs are laid on the pod and using her snout, the weevil pushes them through the hole into the pod.

To save energy and resources, wild white indigo plants often abort pods during ripening, especially those with weevil populations inside. The pods decay and the developing weevils inside die.

References:
Haddock, R. C., & Chaplin, S. J. (1982). Pollination and seed production in two phenologically divergent prairie legumes (Baptisia leucophaea and B. leucantha). American Midland Naturalist, 175-186. Retrieved from http://www.jstor.org/stable/2425307

Horn, S., & Hanula, J. L. (2004). Impact of seed predators on the herb Baptisia lanceolata (Fabales: Fabaceae). Florida Entomologist, 87(3), 398-400.

Petersen, C. E., Petersen, R. E., & Meek, R. (2006). Comparison of common factors affecting seed yield in the congeners, Baptisia alba and Baptisia bracteata. Transactions of the Illinois Academy of Science99, 31-36.

Petersen, C. E., & Sleboda, J. A. (1994). Selective pod abortion by Baptisia leucantha (Fabaceae) as affected by a curculionid seed predator, Apion rostrum (Coleoptera). Great Lakes Entomologist, 27, 143-143. Retrieved from http://insects.ummz.lsa.umich.edu/mes/gle-pdfs/vol27no3. pdf#page=18

Pollination of Prairie Phlox ~ Phlox pilosa

noreply@blogger.com (Heather Holm) — Mon, 08 Jul 2013 22:25:00 +0000

Prairie Phlox ~ Phlox pilosa
The fragrant, pink flowers of prairie phlox are just about finished their display for the season. Prairie phlox is a robust, drought tolerant prairie native that performs best in well-drained soils in full sun.

Use massed on the edges of small prairie plantings or along a sidewalk for a nice effect. The short, upright stature and thin leaves contrast well with larger-leaved prairie perennials such as prairie alumroot which flowers at the same time.

Peck's Skipper Butterfly

Butterlies are the primary pollinator of prairie phlox; they are attracted to the floral fragrance and nectar guides (dark pink marks around the corolla opening).

Nectar is easily accessed by butterflies (and moths) from the disc at the base of the stigma with their long proboscis.

European Skipper Butterfly
taking off from the flower.
Pollen is attached to the proboscis.

As they insert their proboscis into the flowers it comes into contact with the anthers. Pollen attaches to the proboscis and as the butterfly finishes nectaring and moves on to the the next prairie phlox plant, the proboscis coils back into its resting position.

Most of the pollen falls off as the proboscis is coiled, leaving only a small percentage of pollen to be transferred to a receptive stigma on another prairie phlox flower.

Some bumble bee species have tongues long enough to reach the nectar.

An American lady butterfly feeds on nectar.

Hummingbird clearwing moths hover over the flowers and feed on nectar.

Short-tongued bees have no way to reach the nectar in the long tubular flower.

They can however, push their head into the flower opening and reach the anthers near the top of the corolla. The anthers are staggered in the flower corolla, some closer to the top, others out of reach to small bees.

This green sweat bee is feeding on pollen from an anther that was pulled out of the flower tube.

Large and small syrphid (flower) flies land on the tops of the flowers and feed on stray pollen.

Prairie phlox is self-incompatible and therefore requires cross-pollination by insects. In the study by Levin & Berube (1972), the number of pollen grains attached to the proboscis of a visiting butterfly drop by 15% when the proboscis is recoiled, and only 17% of the remaining pollen grains are effectively deposited onto a receptive stigma on another prairie phlox flower visited. Also, only 1% of the pollen that a prairie phlox flower produces is transferred to a stigma on another plant.

Relying on the longer-tongued insects like butterflies and moths to ensure pollination and sexual reproduction of the species is therefore risky as they are so ineffecient at transferring pollen from one prairie phlox plant to another.

References
Hendrix, S. D. (2000). Population size and reproduction in Phlox pilosa. Conservation Biology, 14(1), 304-313.

Levin, D. A., & Berube, D. E. (1972). Phlox and Colias: the efficiency of a pollination system. Evolution, 242-250.

Pollination of Dutchman's Breeches ~ A Royal Affair

noreply@blogger.com (Heather Holm) — Wed, 12 Jun 2013 16:21:00 +0000

Dutchman's Breeches ~ Dicentra cucullaria
Dutchman’s breeches flowers very early in the spring typically at the end of April but this year closer to mid-May. The bright white 'pants' look like they are hanging on a clothes line to dry.

Small plants take a few years to establish and flower but it’s worth the wait; plant in small masses for better effect in a woodland garden. The foliage yellows and dies back by mid-June so it's a good idea to inter-plant with later flowering woodland species such as false solomon’s seal to cover the void left after dormancy.

The timing of flowering of dutchman’s breeches coincides with the emergence of overwintering queen bumble bees. As queen bumble bees emerge from hibernation, they fly low to the ground in woodlands searching for appropriate nesting sites in abandoned rodent holes, leaf piles or other dry locations. The low growing, Dutchman’s breeches serves as an important nectar source to be used in the initial provisioning of their nests.

Queen bumble bees have the tongue length, size and strength to pry open the petals on the flowers. As the flower develops, the bottom of the outer petals reflexes revealing the yellow coloration near the opening. This coloration acts as a visual attractant to visiting queens. They land on the side of the flowers grasping onto the outer petals, they also, as pictured in this photo, grasp onto adjacent flowers with their rear legs.

Once they have a good hold, they rotate their bodies in order to access the flower opening, directing their head toward one of the nectar spurs. Pushing their tongues then heads in between the outer and inner petals opens the flowers and allows them to reach the nectar in the spurs. Pollen is brushed onto their head and thorax, as the inner petals are deflected revealing the anthers. Their front legs often grasp the inner petals which helps expose the anthers and stigma and ultimately transfers pollen onto their forelegs.

Pollen also accumulates on the bottom edges of the petals. The inner petals are hinged and when the bee removes its head from the flower, the petals return to their original position. Pollen that has dropped to the edges of the petals is transferred to the middle legs of the bee. The most important pollen placement for pollination of the next Dutchman's breeches flower visited is on the head and thorax.

Other smaller worker bumble bees chew small holes in the two nectar spurs to steal nectar because they are not strong enough to pry open the petals and have shorter tongues than queen bumble bees.

Even smaller bee species such as Cuckoo bees, Nomada sp. and mining bees, Andrena sp. fly around and occasionally land on the flowers investigating them for a potential reward, but none can be accessed.

Like many other spring-flowering woodland plants, the seeds of Dutchman's breeches are dispersed by ants. Ants are attracted to the protein-rich, fleshy elaiosome attached to the seeds. They carry them back to their nests consuming the elaiosome and discarding the fertile seed in their nest's trash pile.

In the absence of queen bumble bees, the flowers of dutchman’s breeches are self-compatible and often self-pollinate.

References:
Macior, L. W. (1970). The pollination ecology of Dicentra cucullaria. American Journal of Botany, 6-11. Retrieved from: http://www.jstor.org/stable/2440374

Macior, L. W. (1978). Pollination interactions in sympatric Dicentra species. American Journal of Botany, 57-62. Retrieved from: http://www.jstor.org/stable/2442554

Pollination of Downy Yellow Violets ~ An Upside Down Approach

noreply@blogger.com (Heather Holm) — Wed, 29 May 2013 22:06:00 +0000

Downy Yellow Violets ~ Viola pubescens
Downy yellow violets are one of my favorite woodland violets. The heart-shaped leaves set off the bright yellow flowers in early spring. Because of its short stature (6-12"), I use this violet on woodland borders, intermixed with Pennsylvania sedge, rue anemone and virginia waterleaf.

The flowers are attractive to pollinators, especially small bees. The lower petal acts as a nice landing platform and the bold black stripes guide the visitors to the nectar. Nectar is secreted from a gland-like spur on the bottom anthers which are shortened and form a ring around the ovary.

Bees with short tongues such as this shiny, blue, small carpenter bee, Ceratina sp. have a hard time reaching the nectar in the spur. In order to reach the reward, they turn their bodies upside down.

Long-tongued bees like bumble bees stay right side up and push their head into the flower.

Both the right side up and upside down positions cause the style to be pushed upwards. When a right side up bee inserts its head into the flower, the cone formed by the stamens is opened, releasing pollen onto the top of the visitor’s head and thorax. In the upside down position, insects land on the front petal and turn themselves upside down. The style is pushed upwards and pollen is released on the face and lower abdomen of the visitor. Subsequent visits to other violets transfer pollen to the receptive stigma.

Small sweat bees, Lasioglossum sp. are also upside down visitors.

They push their head into the flower as far as possible to try and reach the nectar reward.

Other visitors of downy yellow violet include bee flies (Bombylius sp.), clouded sulphur butterflies (Colias philodice) and Syrphid flies.

References:

Beattie, A. J. (1974). Floral evolution in Viola. Annals of the Missouri Botanical Garden, 781-793. Retrieved from: http://www.jstor.org/stable/2395029

Pollinator Handouts

noreply@blogger.com (Heather Holm) — Mon, 13 May 2013 17:22:00 +0000

You can now download some of the recent handouts I created for pollinators and native plants from the right sidebar of my blog homepage.

More to come, stay tuned!

American Pasqueflower ~ A Welcome Sign of Spring

noreply@blogger.com (Heather Holm) — Sun, 28 Apr 2013 22:27:00 +0000

American pasqueflower ~ Anemone patens

American pasqueflower is a wonderful native alternative to tulips or daffodils, flowering in early spring. It can be found on sunny, prairie slopes with poor, dry soils. This year, it's flowering before any of the woodland ephemerals such as bloodroot, Sanguinaria canadensis. The leaves are held tight to the stem during flowering, looking like a prop holding the flower upwards. These palmately-divided leaves relax away from the stem and open after flowering.

American pasqueflower provides an abundant amount of pollen to pollinators, an important, early-spring resource for female bees to provision their nests. The plant is protogynous, developing the female parts first (stigmas), with the male anthers shedding pollen after the stigmas are no longer receptive. This is one of many fascinating strategies to ensure cross-pollination. In order to attract pollinators during the male phase, small staminal nectaries located at the base of the stamens produce nectar. It is likely that a visiting insect seeking nectar only will come into contact with the anthers transferring pollen on their bodies to the next pasqueflower.

The flowers when open, track the sun throughout the day turning the flowerheads. This solar tracking (heliotropism) tends to occur in plant families that flower when pollinators are scarce. The flowers facing the sun trap the sun's heat creating a warm place for pollinators to forage and warm body temperatures. The pollinators have little difficulty flying to the next flower when warm, aiding in the cross-pollination of the plant.

Small Sweat Bees, Lasioglossum spp.
Frequent visitors, small sweat bees collect the white pollen which is abundant, circling around the outside of the numerous stamens on each flower.

Large Mining Bees, Andrena spp.
Large mining bees belonging to the Melandrena subgenus are common in early spring and can be mistaken for bumble bees. They have shiny, black abdomens, unlike bumble bees who have hairy abdomens. Mining bees nest in the ground in sand or loose, loam soils.

Other pollinators to look for include large syrphid flies feeding on pollen. These flies are mimics of large mining bees and bumble bees. Bumble bees also visit the flowers.

Because American pasqueflower blooms in early spring during fluctuating temperatures, insect activity can be sporadic. If the sepals are closed on a cool day, look for bees forcing their way into the flower.

References:
Bock, J. H., & Peterson, S. J. (1975). Reproductive biology of Pulsatilla patens (Ranunculaceae). American Midland Naturalist, 476-478. Retrieved from: http://www.jstor.org/stable/2424441

Emerald Ash Borer Treatment- Toxic To Bees?

noreply@blogger.com (Heather Holm) — Fri, 22 Mar 2013 21:14:00 +0000

Image Source: Wikipedia

The emerald ash borer, Agrilus planipennis a beetle native to China, Japan and Korea was introduced into North America in the Great Lakes area in the early 1990's and populations were identified in 2002. It is suspected that this beetle was introduced from ash shipping crates. Emerald ash borer beetle larva burrow through the outer bark of ash trees, Fraxinus spp. and into the living cambium tissue.

As the larvae feed on the cambium, they create 'S'-shaped galleries in the wood. The galleries created from a large infestation weaken the ash trees causing canopy thinning and eventually canopy die-back. A secondary symptom is numerous shoots forming around the base of the ash tree.

Current Map of Emerald Ash Borer Range
Source: emeraldashborer.info

As a homeowner living in Minnesota just outside the range of emerald ash borer, I started to research the treatments being offered by local tree care companies. I only have one ash tree on my property and do not plan to treat it but many of the suburban neighborhoods in the Twin Cities were heavily planted with ash trees in the late 1970's and early 1980's. I am reminded when driving through these neighborhoods that planting a diversity of native plant species in your landscape will help with weathering the impacts from invasive species and climate change.

"Systemic insecticides containing the active ingredients imidacloprid, dinotefuran or emamectin benzoate are commonly used to protect ash trees from EAB." (Potential Side Effects of EAB Insecticides) Imidacloprid belongs to the group of neonicotinoid insecticides which has been linked to Colony Collapse Disorder (CCD). Read a recent Xerces Society report here: Are Neonicotinoids Killing Bees? Today, a coalition of bee-keepers have filed a suit against the EPA for failing to suspend the use of neonicotinoid pesticides.

Imidacloprid, sold under the trade names Merit, Xytect, Optrol, ArmorTech, Enforce, Hawk-I, Turfthor, Malice, Premis, Criterion, Hunter, Submerge and Touchstone is typically applied as a soil drench or soil injection annually as a preventative treatment for emerald ash borer. For a homeowner with several ash trees, the cost can be very high. The city of Minneapolis now recommends replacing ash trees on residential properties rather than treating them due to the environmental risks from the treatments including, leaching into the surface or ground water, uptake by other plants visited by pollinators for nectar and pollen and non-target effects on woodpeckers feeding on EAB larvae.

Are your ash trees worth saving or should you be preparing for their replacement? Are the risks of using neonicotinoids too high? Purdue University offers a cost calculator for EAB treatment for homeowners here. Trees with structural defects, poorly sited, or with no historical or aesthetic value should not be treated. Read more guidelines here.

Perhaps our efforts should be focused on the conservation of ash tree species. Volunteers are needed for the collection of ash seeds to help preserve genetic variation and with a long-term goal of the reintroduction of ash trees into affected areas. Find out more information on how you can help collect ash tree seeds.

References:
The Effects of Neonicotinoids on Honey and Bumble Bees.Vera Krischik, Entomology, University of Minnesota.
Chemicals Implicated. BeyondPesticides.org
Blacquiere, T., Smagghe, G., Van Gestel, C. A., & Mommaerts, V. (2012). Neonicotinoids in bees: a review on concentrations, side-effects and risk assessment. Ecotoxicology, 1-20.
Emerald Ash Borer Info

Wild Geranium Pollinators & Floral Visitors

noreply@blogger.com (Heather Holm) — Mon, 11 Mar 2013 16:51:00 +0000

Like many spring-flowering native plants, wild geranium flowers have the ability to self-pollinate when no pollinators are present. However, the flower matures to ensure cross-pollination when insects are present, with the row of outer anthers developing on the first or second day after the flowers open, followed by the inner row on the second or third day. The stigma becomes receptive after the anthers have dehisced on the third or forth day.

Bees, flies and beetles visit the flower for nectar and pollen. Nectar is secreted from five glands located between the stamens and sepals. In a study by Bertin et al, bees visiting for nectar were responsible for depositing more pollen than pollen collecting bees. Larger bees such as bumble bees and mason bees are considered effective pollinators because pollen brushed onto the underside of their abdomen contacts the stigma. Smaller bees are able to circle around the base of the stamens feeding on nectar without coming into contact with pollen from the anthers above.

Wild geranium flowers are over one inch in width and extremely showy. Dark lines on the flowers act as nectar guides, showing pollinators the location of the nectaries at the base of the stamens.

Small Carpenter Bees, Ceratina spp.
Smaller bee species circle the base of the flower seeking out nectar without coming in contact with the anthers and stigmas above.

Cuckoo Bees, Nomada spp.
Wild geranium is a nectar source for this cuckoo bee in early spring. Female Nomada bees lay their eggs in the nests of ground nesting native bees, especially mining bees (Andrena spp.). The cuckoo bee eggs hatch and the larvae kills the host bee larvae and consumes the provisions provided by the host. Nomada bees are reddish-brown to black with yellow or white markings.

Mason Bees Osmia spp.
Mason bees visit wild geranium for both pollen and nectar. Females land on top of the anthers gathering them together with her legs. Pollen is brushed onto the pollen-collecting hairs on the underside of the abdomen. Wild geranium is an important source of pollen and nectar for mason bees, it flowers when females are provisioning their nests.

Sweat Bees Lasioglossum spp.
Sweat bees visit the flowers to feed on nectar.

Fruitworm Beetles Byturus unicolor
Long, dense hairs cover the elytra of these beetles where pollen grains attach. Adults emerge from the soil in early spring, feed on host plants (raspberries, blackberries and avens), mate, then lay eggs. Larvae burrow into the flower buds and fruit of the host species and buds drop off or decay. Fruit becomes misshapen and ‘wormy’. Look for adult beetles feeding on the pollen of woodland natives in early spring such as Viriginia waterleaf and wild geranium.

References
Bertin, R. I., & Sholes, O. D. (1993). Weather, pollination and the phenology of Geranium maculatum. American Midland Naturalist, 52-66. Retrieved from: http://www.jstor.org/stable/2426435

Willson, M. F., Miller, L. J., & Rathcke, B. J. (1979). Floral display in Phlox and Geranium: adaptive aspects. Evolution, 52-63. Retrieved from: http://www.jstor.org/stable/2407365

Ten Great Native Plants for Dry, Sandy Soils

noreply@blogger.com (Heather Holm) — Tue, 26 Feb 2013 17:37:00 +0000

Flower: June - Late July | Exposure: Full Sun

Soil Moisture: Mesic to Dry | Soil Type: Sand to Loam

Butterfly milkweed develops a substantial taproot and is not easy to transplant. Find the right sunny location and let it grow. It is an excellent plant for pollinators, and a larval host plant for the monarch butterfly, queen butterfly and milkweed tussock moth caterpillar.

Flower: Late April - June | Exposure: Full Sun

Soil Moisture: Mesic to Dry | Soil Type: Sand to Loam

Prairie smoke's most unique feature is the wispy, feathery ends attached to the seeds that persist into the summer and wave in the wind. The fern-like foliage stays green under the snow and is a welcome sight in spring. Prairie smoke is pollinated by bumble bees who use buzz pollination to release the pollen from pores.

Flower: June - September | Exposure: Full - Part Sun

Soil Moisture: Mesic to Dry | Soil Type: Sand to Loam

Harebell has a fine, dainty form but is very tolerant of tough sites. It's native range covers most of North America except for the southern-most states. It likes high alpine rocky terrain, growing from cracks in rocks on the edge of lake superior and sandy bluffs.

Flower: July - October | Exposure: Full - Part Sun

Soil Moisture: Mesic to Dry | Soil Type: Sand to Clay/Loam

Stiff goldenrod is a well behaved goldenrod with an upright form and large flat-topped flowerheads. The flowers are very long-lasting and combine well with prairie grasses such as little bluestem. An absolute pollinator magnet in late summer, the shallow disc flowers allow most types of pollinators access to nectar.

Flower: July - September | Exposure: Full Sun

Soil Moisture: Dry Mesic to Dry | Soil Type: Sand to Sandy Loam

Spotted bee balm can be short lived but if planted in suitable sites will reseed enough to maintain a stand. The interesting whorled/tiered flowers are unique, the lower bracts can range from pink to white in color. If you're looking for a plant that stands out at dusk, this is a good candidate.

It a larval host plant for the gray marvel moth and two snout moths, Pyrausta spp.

Flower: July - September | Exposure: Full Sun

Soil Moisture: Mesic to Dry | Soil Type: Sand to Loam

Hoary vervain is common in disturbed sites with sandy soils. It is a great performer in the garden, with an upright form and showy flowers arranged on narrow spikes. The flowers open from the bottom upwards and are visited by bees and butterflies for the nectar. It a larval host plant for the verbena moth and fine-lined sallow moth.

Flower: May - June | Exposure: Full - Part Sun

Soil Moisture: Dry Mesic to Dry | Soil Type: Sand to Sandy Loam

Wild lupine loves sandy soils. It is an excellent perennial for early spring color. The flowers lack nectar but it still attracts bumble bees and mason bees for pollen. It a larval host plant for the endangered karner blue butterfly, as well as several duskywings and sulphur butterflies.

Flower: June - September | Exposure: Full - Part Sun

Soil Moisture: Mesic to Dry | Soil Type: Sand to Clay/Loam

You can't find a more versatile plant than black-eyed susans. It flowers in its first year from seedlings, reblooms throughout the summer months, and is very showy. It can be short-lived but but reseeds. It a larval host plant for the wavy-lined and southern emerald moths, and the

silvery checkerspot butterfly.

Flower: June - September | Exposure: Full - Part Sun

Soil Moisture: Mesic to Dry | Soil Type: Sand to Clay/Loam

Fragrant hyssop belongs to the mint family, and like many plants in this family the leaves are fragrant. If you like black licorice, then you will enjoy nibbling on the leaves of fragrant hyssop.

It can get quite tall in soils that are too rich - close to 60", but in dry prairies 30" is more typical. It works well to mass this plant which highlights the range in flower colors from light blue to dark

purple.

Milkweed Pollination - A Sticky Situation

noreply@blogger.com (Heather Holm) — Fri, 15 Feb 2013 16:43:00 +0000

Milkweed plants, Asclepias spp. have a unique method of transferring pollen from one plant to the other for cross-pollination. Pollen is aggregated in sac-like bundles called pollinia, located on either side of the stigmatic chamber. The two bundles are strung together with a gland (filament) at the top of the stigmatic chamber.

Bees, wasps, flies, beetles and butterflies visit the flowers for nectar. Milkweed plants typically produce a lot of nectar, it is replenished overnight, to the delight of nocturnal moths, and the remaining nectar is ready for the first diurnal visitors in the morning.

For accessing nectar, floral visitors prop themselves on one of the five flower hoods, sliding their tongues down the side of the hood where the nectar is held. They must be careful not to slip their leg down into the flower between the anthers.

When pulling their leg out, they could snag it on the filament holding together the sticky pollinia sacs.

Pollina stuck to the legs of a great
black wasp, Sphex pensylvanicus

The sticky pollinium sacs are carried to other milkweed plants on their legs and if the insect again ‘slips’ the pollinia can be inserted into the stigmatic chamber ensuring cross-pollination. Unable to pull their leg out, smaller bees can become trapped in the flowers and perish.

In a study by Fishbein and Venable (1996), small- and medium-sized bees, and medium-sized butterflies had the lowest removal rates of pollinia. Their study found that it was the larger bees, like bumble bees that were most effective at transferring pollinia from one plant to the other.

Leafcutter bee, Megachile sp. alighting
on top of the flower hoods to nectar.

Ivey et al. (2003), also found large carpenter bees, Xylocopa spp. and bumble bees, Bombus spp. effective pollinators, partly due to their foraging efficiency; they visit flowers methodically, probing all the hoods of a flower, and visiting more flowers per flowerhead.

Leafcutter bees are common visitors of milkweed feeding on nectar. They rarely snag pollinium sacs so are considered ineffective pollinators.

Small carpenter bees, Ceratina spp. prop themselves on the top of the hood and slide their tongue down the side of the hood to reach nectar.

Cuckoo bees, Coelioxys spp. are true nectar thieves. The have no pollen-collecting structures on their legs. They only visit flowers for nectar because they are cleptoparasites, laying their eggs in the nests of other bees.

This particular cuckoo bee is a cleptoparasite of leafcutter bees, Megachile spp. Females have a tapered abdomen ending in a sharp point that is used to break through leafcutter brood cells.

Another example of a small-sized bee, yellow faced bees, Hylaeus spp. are frequent visitors to swamp milkweed in late summer for nectar.

Soldier beetles, Chauliognathus spp. also love to feed on nectar on milkweed plants but are rarely found carrying pollinia.

What seems to be a not-so-mutualistic relationship between floral visitor and plant, where floral visitors are exploiting nectar resources, cross-pollination is still occurring due to the effective visitation by large bees, who transfer the polllinium sacs from one plant to another.

References
Fishbein, M., & Venable, D. L. (1996). Diversity and temporal change in the effective pollinators of Asclepias tuberosa. Ecology, 1061-1073.

Ivey, C. T., Martinez, P., & Wyatt, R. (2003). Variation in pollinator effectiveness in swamp milkweed, Asclepias incarnata (Apocynaceae). American Journal of Botany, 90(2), 214-225.

Kephart, S. R. (1983). The partitioning of pollinators among three species of Asclepias. Ecology, 120-133.

Plan Now for Spring Pollinators

noreply@blogger.com (Heather Holm) — Mon, 04 Feb 2013 21:02:00 +0000

Grass-carrying Wasps ~ Isodontia spp.

noreply@blogger.com (Heather Holm) — Tue, 29 Jan 2013 15:33:00 +0000

Grass-carrying Wasps ~ Isodontia spp.

Grass-carrying wasps are a flower-visiting solitary wasp, common in late summer and early fall. Because they are solitary-nesting, and not colonial like yellowjackets or hornets, they do not sting humans to defend their nests. It's an important distinction to make with wasps in our landscapes, so many are solitary and not aggressive.

They perform important ecosystem services, pollinating the plants in our landscape, and preying on foliage eating insects, crickets and katydids in particular.

Females look for prey, stinging them several times to paralyze and immobilize them. They carry their prey back to their nests, which are preexisting cavities such as hollow stems or holes bored in wood.

The paralyzed prey are stocked for their developing larvae to feed upon. Using nearby grasses, nests are divided into sections with pieces of grass, they also close the end of nest with grass.

If you erect a mason bee nest board (board with nesting holes drilled in it), grass-carrying wasps will sometimes build nests in the cavities. Look for pieces of grass sticking out the ends of the board holes or plant stems.

I have several different variations of stem nests hung in the yard for solitary bees (and wasps), this one in particular has been utilized almost exclusively by grass-carrying wasps. Cup plant and pale Indian plantain stems work extremely well, both are hollow.

Here's a cross-section of one of those stems with the wasp larvae and stocked prey. In my yard, the grass-carrying wasps like to use little bluestem to seal off the cavities.

Look for grass-carrying wasps in late summer. In my yard, they like to visit stiff goldenrod, common boneset and pale Indian plantain flowers for nectar.

12 Great Native Plants for the Mesic Woodland Garden

noreply@blogger.com (Heather Holm) — Thu, 17 Jan 2013 17:08:00 +0000

If you are planning a woodland garden, or already have one established, these 12 native plants are definitely worth considering. One of the major components in developing a native woodland garden is to build, and establish a good duff layer of leaves and humus.

If you are just starting out, don't throw your leaves away in the fall, woodland natives need the protection of leaves to help keep their roots cool in summer, and blanketed in winter.

Bishop's Cap has extremely dainty flowers, the petals are fringed and look like snow flakes. This native plant is similar in growth habit to Heuchera species, with a cluster of basal leaves and long narrow flower stalks.

It blooms from May to June and likes sandy-loam to loam soils, dry-mesic to mesic moisture.

It spreads by rhizomes forming a nice mass once established. Combine with woodland phlox or large flowered bellwort.

Wild Geranium is one of my favorites, flowering from April to June, the large pink to purple flowers are extremely showy and abundant. It has a mounding habit with attractive palmately-divided leaves that turn bright red in the fall. Combine with false solomon's seal, and woodland phlox. It can get up to three feet tall in rich soils, so don't plant next to tiny ephemerals that can get overpowered by wild geranium.

Woodland phlox flowers can be a soft blue, pink or white. The large, five-parted flowers are showy and held above attractive foliage. Woodland phlox can be browsed by herbivores. It flowers from April to June. Utilize woodland phlox inter planted with other smaller-statured natives such as downy yellow violets or large flowered bellwort.

The white umbel flowerheads of long-styled sweet cicely brighten any shaded woodland garden. Stems are dark maroon in color with fern-like compound leaves. Flowers from May to June, combine with Wild Geranium.

Virginia waterleaf is extremely easy to grow, it readily reseeds once you have some established plants. The young leaves are speckled with silver to white spots. Pink to purple flowers arranged in cyme bloom from late April to June. Virginia waterleaf can reach heights of 24", but more typically the flowerheads top out at 12-16". Combine with false solomon's seal and downy yellow violets near the edge of your woodland planting.

Wild Ginger is a very attractive, low growing native. Often used massed for best effect, the red to maroon flowers develop under the leaves and are not always visible. The foliage however, looks great through the summer months in mesic soils. It spreads by rhizomes and easy to divide. Seeds are dispersed by ants.

Blue cohosh flowers in early spring from April to May. It is a tall plant, usually reaching heights over 30". The compound foliage has soft, delicate leaflets that set off the panicle of green-yellow flowers. The resulting fruit looks like a cluster of blue berries, but it's actually a hard seed covered by a blue skin. Make sure you have plenty of leaf litter and soils rich in humus.

White baneberry has many great attributes including its white flowers that bloom from May to June, followed by a cluster of white berries with a black dot on the end. The other common name for white baneberry is doll's eyes, named after the fruit. Red baneberry is similar, withstanding drier soils than white baneberry and the fruit is bright red. It flowers a few weeks before white baneberry.

Another woodland plant that is rhizomatous. The large, terminal flowerheads are extremely showy, and the flower stem zigzags slightly as it arches over. It flowers from May to June and is very tolerant of drier woodland soils, great to utilize under trees.

Early meadow rue has softly lobed foliage and delicate flowers that dangle downwards. The plants produce either male or female flowers, the male flowers are showier; bright yellow anthers mature and flutter in the slightest breeze.
Very good plant for dry soils.

The native plants above all flower in the spring; for some interest in late summer in the woodland garden, try big-leaved aster. It can start flowering in late July and continue into September. As the common name suggests, the leaves are large and slightly heart-shaped. Many white to light blue flowers are arranged in a flat-topped flowerhead (panicle). This native spreads by rhizomes and forms a dense cluster. It performs best in mesic soils.

One of the most shade-tolerant goldenrod species, zigzag goldenrod flowers from mid August to October. The bright yellow flowers are a welcome site in the woodland landscape. The leaves are very attractive with serrated edge and pointed tips. The common name is for the zigzagging flower stalk.

Harebell ~ Campanula rotundifolia Pollinators & Floral Visitors

noreply@blogger.com (Heather Holm) — Fri, 04 Jan 2013 16:32:00 +0000

Harebell ~ Campanula rotundifolia

Typically, small to medium sized bees visit harebell flowers. The five-parted, nodding flowers have a prominent, large, central style that may restrict access to large bees such as bumble bees. Bumble bees could reach the nectaries with their long tongues, but I have not seen one attempt this. Every visiting insect has a different approach and objective while visiting the flowers, some affect the rate of the flower development process and others get away with feeding on nectar without aiding in cross-pollination.

Filament bases surround the nectar-producing disc at the bottom of the style. When harebell anthers release pollen, the tube formed by the filaments around the style traps pollen. As the style elongates, the pollen collecting hairs on the style push the pollen upwards, exposing the pollen to pollinators.

The pollen collecting hairs are stimulated by visiting insects, more stimulation with pollen feeding, and less with nectar feeding. The more the hairs are stimulated, the shorter the duration of the male phase. Hairs retract causing the remaining pollen to fall out of the nodding flower. The female phase then begins with the separation of the stigma. This process, accelerated by pollinators, ensures cross-pollination of the flowers.

Leafcutter Bees ~ Megachile spp.
Leafcutter bees are frequent visitors of harebell feeding on nectar. Their pollen-collecting hairs (scopa) on the underside on their abdomens come into contact with the pollen held on the style.

Digger Bees ~ Anthophora spp.
Long tongues allow digger bees to reach the nectar at the base of the style and avoid contact with pollen on the style. The flower in this image has released all the pollen, the filaments are drying up and the stigma is preparing to separate to receive pollen.

Green Sweat Bees ~ Agapostemon spp.
Green sweat bees visit harebell flowers for nectar. This bee is holding itself in the nodding flower by grasping onto the base of the style. The stigmas have separated and are ready to receive pollen transferred from visiting insects.

Small Carpenter Bees ~ Ceratina spp.
Small carpenter bees are some of the early visitors of harebell flower development. After the style elongates and the pollen collecting hairs are covered with pollen, small carpenter bees visit and feed on and collect pollen stuck stigma.

References
Attracting Native Pollinators: The Xerces Society Guide, Protecting North America's Bees and Butterflies 
The Pollen-Collecting Hairs of Campanula (Campanulaceae). II. Function and Adaptive Significance in Relation to Pollination. Yvonne Nyman. American Journal of Botany , Vol. 80, No. 12 (Dec., 1993), pp. 1437-1443

Wasps in the Wildlife Garden

noreply@blogger.com (Heather Holm) — Fri, 21 Dec 2012 17:05:00 +0000

Did you know that most wasps are solitary nesting and don't sting humans?

There are some fascinating wasp species that visit our garden plants for nectar, and use our landscape to hunt for food for their young including caterpillars, sawfly larvae, crickets and katydids.

Find out more about the behavior and lifecycles of some of the wasps who share our landscape with us on my post this week at Native Plants Wildlife Gardens.

Native Bee Spotlight: Green Sweat Bees ~ Agapostemon spp.

noreply@blogger.com (Heather Holm) — Thu, 13 Dec 2012 16:49:00 +0000

Green Sweat Bees (Metallic Green Bees) ~ Agapostemon spp.

Green Sweat Bees are one of the most brightly colored native bees in our area. A bright emerald green head and thorax, with a striped abdomen of pale to bright yellow. Some females in this genus are entirely green, and often difficult to distinguish from bees in the Augochlora genus.

We see Green Sweat Bees in late May, some of the first females visit Ohio Spiderwort (Tradescantia ohiensis) to collect and feed on pollen. No nectar is offered by this native. Read about other visitors to Spiderwort here.

Green Sweat Bees nest in the ground, building long vertical nest cavities. Most are solitary nesting like the majority of native bees, but some species share the same nest entrance but build their own cavities.

Another good source of pollen for Green Sweat Bee females in early spring is Great St. John's Wort (Hypericum pyramidatum).

Green Sweat Bees are short tongued, so they visit shallow or easily accessible flowers for nectar. They like to visit both the prairie native Hoary Vervain (Verbena stricta), found in dry, sunny locales as well as the wetland native Blue Vervain, Verbena hastata for nectar.

Visiting Blue Vervain for nectar.

Look for Green Sweat Bees on Coneflower (Echinacea) species. Females collected pollen and feed on nectar on our Pale Purple Coneflower.

They will investigate the flowers of Wild Bergamot, possibly feeding on pollen but cannot reach the nectar in the long flower tubes.

Culver's Root (Veronicastrum virginicum) is a late summer favorite of Green Sweat Bees. The numerous shallow white tubular flowers provide an abundance of nectar.

Look for Green Sweat Bees in late summer on Cup Plant (Silphium perfoliatum) as well as many of the fall flowering Asters.

These native bees are fast moving and camera shy. It's often difficult to capture them because their flower visits are very short, so have your camera ready if you spot one.

References:
Attracting Native Pollinators: The Xerces Society Guide, Protecting North America's Bees and Butterflies 

Tall Beard Tongue Insect Visitors

noreply@blogger.com (Heather Holm) — Fri, 07 Dec 2012 21:16:00 +0000

Tall Beard Tongue ~ Penstemon digitalis
Beard tongue flowers have a large, hairy staminode on the lower half of the tubular flower which restricts access to bees to the flower and helps in pollen deposition. Small to medium sized bees are the most frequent visitors.

Tall Beard Tongue flowers can be white to light pink, sometimes with darker pink to purple stripes which act as nectar guides for bees.

Small Carpenter Bees (Ceratina spp.) visit Tall Beard Tongue flowers primarily to feed on pollen. Their small size allows them to easily climb over the staminode into the tubular flowers to access the pollen on the anthers.

As they feed on pollen, they often inadvertently contact the stigma. The hairs on the staminode keep their bodies held closer to the stigma, resulting in more contact and pollen transfer.

Digger Bees (Anthophora spp.) are frequent visitors to Tall Beard Tongue flowers as well. They are fast moving and visit flowers for a very short time frame compared to Small Carpenter Bees.

Their medium sized bodies and long tongues allow them access into the tubular flower which results in abundant pollen removal as their bodies scrape on the anthers above.

Bumble Bees (Bombus spp.) are not primary pollinators of Tall Beard Tongue. Visiting the flowers for nectar, they are able to reach the nectar reward with their long tongues without having to insert their body into the corolla and come away with pollen on their bodies.

Look for small holes chewed at the base of the flower. Mason Wasps will chew holes to reach the nectar reward without having to enter the flower. Smaller bees will take advantage of these nectar thievery holes.

References:
Attracting Native Pollinators: The Xerces Society Guide, Protecting North America's Bees and Butterflies

The Interaction between Pollinator Size and the Bristle Staminode of Penstemon digitalis (Scrophulariaceae) Gregg Dieringer and Leticia Cabrera R. American Journal of Botany , Vol. 89, No. 6 (Jun., 2002), pp. 991-997

Native Bee Spotlight: Yellow Faced Bees ~ Hylaeus spp.

noreply@blogger.com (Heather Holm) — Fri, 30 Nov 2012 20:57:00 +0000

Yellow Faced Bees ~ Hylaeus spp.

Yellow Faced Bees are tiny black bees with yellow (sometimes white) markings on their face, thorax and legs. Often mistaken for tiny solitary wasps, these bees have quite shiny bodies due to the lack of hairs.

Occurring from late May through to September, we will see Yellow Faced Bees in early spring, then again in late summer with a gap in between.

Some of the first native plants to look for Yellow Faced Bees in spring are Golden Alexanders (Zizia spp.). This female is feeding on pollen of Golden Alexander. Yellow Faced Bees are different from other native bees because they collect pollen and nectar in their crop. They have no pollen-collecting combs on their legs or abdomens.

Pollen is brushed with their forelegs from their head and thorax and then collected in the mouth.

Females collect pollen and nectar, and regurgitate the liquid mixture to provision the brood cells. An egg is laid on top of the mixture where the larva will hatch and consume the liquid.

Yellow Faced Bees nest in cavities, tunnels in pithy wood, or even holes in wood. Their brood cells are separated with a cellophane like material.

A Yellow Faced Bee visiting Canada Anemone (Anemone canadensis) for pollen in early spring.

In late summer look for Yellow Faced Bees nectaring on Swamp Milkweed (Asclepias incarnata). I had several dozen visiting just one plant this summer.

Although Yellow Faced Bees are short-tongued, their small size allows them access to the nectar of many flowers.

They also visit Common Boneset (Eupatorium perfoliatum) in late summer.

Source: Attracting Native Pollinators: The Xerces Society Guide, Protecting North America's Bees and Butterflies