Insect Observation Group of YBA Sri Lanka

Dragonflise of Sri Lanka

2011-07-31T21:46:00.000-07:00

Life Cycle of A Dragonfly

(Drawing: M. Bedjanič)

(1) Mating (2) Egg-laying (3-6) larval development

(7) last moulting – emergence (8) adult insect

The dragonfly has an incomplete metamorphosis, which consists of egg and several larval stages followed directly by the adult phase. Adult phase is characteristic of dragonflies. Dragonfly is an insect whose adult wings are beautifully colored. It can be met along rivers, streams, paddy fields, marshes, pools and lakes almost year round, represent only the shorter phase of their life cycle. They spend most of their lives hidden from human eyes as larvae in the water.

Female adult lays eggs in plant tissue or drops freely into the water. Larvae develop from eggs. The first larva, Nymph 1 is very small. After passing several moults the larva becomes proportionally larger. It’s Nymph 2. Larvae appear as a rough bodied clumsy looking creature with spidery legs and have very little in common with the beautiful winged adults. Both larvae and adults are ravenous and predatory animals. Larva has a modified lower lip, which is folded beneath the head at rest but can grasp prey with lightning speed. They eat small aquatic insects, such as mosquito larvae, and sometimes they feed on smaller fishes.

When the wings of the larva ready to emerge, it climbs out of the water and emerge from the tight larval case. Though it expands its soft wings and flies away, its wings aren’t developed brighter colours. Their attractive colouration develops only after several days of their emergence. Male dragonflies are usually found near aquatic surroundings. As well as feeding, they are very active in finding a female. Female are found on the water when they mate or lay eggs, except these occasions they are fond of living away from the water and feed at forest edges and clearing to avoid contact with the male.

Mating,

it’s an interesting act in the nature, mating in dragonflies. The primary sexual organs of both male’s and female’s, are situated at the end of the abdomen. They aren’t in direct contact during mating. Underneath the second and third abdominal segment, the male has so called secondary genital organs where sperm is transferred from the abdomen tip. The female, still securely held by the male’s anal appendages, bends her abdomen and genitalia to the secondary genitalia of the male and the partners are joined. This beautiful heart-shaped figure is called a “wheel” or “copula”.

Dragonflise of Sri Lanka

2011-07-26T05:32:00.000-07:00

Dragonflies of Sri Lanka

Classification

Kingdom Animalia
Phylum Arthropoda
Class Insecta
Order Odonata

We have a large amount of dragonfly species in Sri Lanka. Among them, some are common to Asia and some of them are endemic species. There are 117 dragonfly species and ,out of them 53 species can be found nowhere else. Dragonflies can be found throughout the year all over the country.

A dragonfly is an insect belonging to the order Odonata. Dragonfly (Order Odonata) has 3 suborders and 2 suborders are present in Sri Lanka. Damselflies belong to the suborder Zygoptera, Dragonflies belong to the suborder Anisoptera. It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body. Dragonflies are similar to damselflies, but the adults can be differentiated by the fact that the wings of most dragonflies are held away from, and perpendicular to the body when at rest. Dragonflies possess six legs (like any other insect), but most of them cannot walk well. Dragonflies are some of the fastest insects in the world.

Families of dragonflies

Aeshnidae
Austropetaliidae
Chlorogomphidae
Cordulegastridae
Corduliidae
Libellulidae
Neopetaliidae
Petaluridae
Synthemistidae

Dragonflies are valuable predators. They eat mosquitoes, and other small insects like flies, bees, ants, and very rarely butterflies. They are usually found around lakes, ponds, streams and wetlands. That because of their larvae, known as "nymphs", are aquatic.

Blue Oak Leaf

2011-07-18T03:20:00.000-07:00

Blue Oak Leaf

This is one of the interesting butterflies in the butterfly world. It’s because of its amazing wings, which are similar to a dry leaf both in shape and color. It is highly difficult to identify in low lit rain forest. They take to wings with the least disturbance, and splashing blue colors of the upper side of wings are really amazing. When they settle in a branch, it may be very difficult to you to trace this butterfly, though the tree or the branch is nearby to you, simply they vanish in the nature. This method of covering invisible is the adaptation of the insect which resembles some special object to which an enemy is indifferent. These butterflies have various types of color and pattern which help them to appear as a dead leaf. When it is chased by a bird, it flies and perch on a branch or a trunk of tree. Then, it flaps its body, as if it is a dry leaf of the tree, which is moving because of the wind. It makes the bird confuse and puzzling, and the bird, flies away as it is difficult find the butterfly.

During the dry season, the upper side is indigo-blue in color. Underside simulating a dry leaf, Antennae dark brown; head, thorax and abdomen very dark greenish brown; beneath, the palpi, thorax and abdomen ochraceous earthy brown.

During the wet-season they have a uniform pale blue of a slightly lighter or darker shade, varying individually, but not turning to white towards the costal margin as in the dry-season specimens. Underside: ground-color on the whole darker than in the dry-season form, but with the same coloring.

South Indian Blue Oakleaf (Kallima horsfieldi)

Lime Butterfly

2011-07-11T21:02:00.000-07:00

Lime Butterfly

Common name - Lime Butterfly

Scientific name - Papilio demoleus demoleusss

Sinhala name - Dehirisiya

Family - Papilionedae

(In Sri Lanka, there are 15 species belong to this family)

The Lime Butterfly occurs in both the Low-Country Wet and Dry Zones. They are becoming more common during the annual migrating season of the butterflies, from about October to March.

The butterflies of this family are popularly called “Swallowtails” owing to the fact that most of them are seen to sport fairly long appendages (a thing that has attached) on their hind wings in flight.

This butterfly has a wingspan of 80-90mm.The Lime Butterfly is normally identified by its rich yellow speckling on the wings and body.

Life Cycle

Eggs

The Lime Butterfly lays its eggs mainly on the lime tree, that’s the reason this so called butterfly gets its name. And also this butterfly lays its eggs in Orange, Bael, Manderine, Pomelo and various other plants of the Rutacea Family. It favours laying eggs under tender leaves.

The egg is pale yellow in colour,but turns rather brownish towards hatching.

Larva

The newly hatched larva is 2.5mm long and as with all others in the family resembles a bird’s dropping, being black with a whitish V- shaped mark in the middle of the body.

Soon after the hatching the larva consumes the empty egg shell as its first meal. Passing several stages of moulting(in the process of renewing), the larva reaches maturity by about the 17^thday after hatching from egg. The full grown larva is 34mm long and7mm broad.

As a whole it is yellowish green, with discs in the front and rear, each equipped with a pair of brown horns, whose tips are yellow. Burnt sienna coloured patches on either side of body, starting from the white marginal band below and slanting upward are conspicuous. There is another shorter, similar coloured patch at the base of the 10^th segment. These patches are thinly speckled with yellow and brown. Three spots of similar colours are on the dorsum of segments 8, 9 and 10^th. Above the spots are two sharp fleshy black processes, tipped white. The legs and pro-legs are brown, the latter covered with soft hairy growth.

Pupa (the insect in the stage between larva and imago)

At the end of the larval period of between 15 to 17 days, the larva stops feeding and prepares itself for pupation on the underside of a leaf stalk.

The pupa is generally inactive and well camouflaged. It is 30*9mm in size. Rounded and overall green in color, paler towards the tail-end and yellowish on the back. There are several rows of short tubercular processes on the back and on the underside there are more processes over the front wing-bud. The pupa is bent backward and dorsally broad and stocky. The head is swollen, the frontal projection almost absent and its margin slightly curved. The thorax is high but less pointed.

Imago(the adult butterfly)

The imago come out from the pupal case within 9 to 11 days time and hangs downwards a while, until the blood containing oxygen passes to the wings through vein system. This process takes from 30 to 45 minutes, before the wings expand and dry up enabling the insect to fly away.

Insect Observation Group of YBA Sri Lanka: Ants

2011-06-17T06:22:00.000-07:00

Insect Observation Group of YBA Sri Lanka: Ants: "Phylum - Arthropoda Class - Insecta Order - Hymenoptera Family - Formicdae How to Identify? Antenna geniculate. 2 nd abdom..."

Ants

2011-04-25T22:08:00.000-07:00

Phylum - Arthropoda

Class - Insecta

Order - Hymenoptera

Family - Formicdae

How to Identify?

Antenna geniculate.
2nd abdominal segment often reduced forming an isolated node or a scale (petiole).
3rd abdominal segment often reduced (post-petiole).

The General life cycle of an Ant colony

(a) Colony founding phase.
(b) Phase of colony growth.
(c) Reproductive phase of a colony.

Taxonomically important Morphological Features of Worker Ants

Head.
Alitrunk (mesosoma).
Waist.
Gaster.

Ants of Sri Lanka

Nine subfamilies of worker ants have been recorded from Sri Lanka.

Aenictinae
Aneuretinae
Cerapachyinae
Dorylinae
Dolichoderinae
Formicinae
Myrmicinae
Ponerinae
Pseudomyrmecinae

Field and Laboratory methods for the study of Ants

Field sampling methods for Ants.

It depends on the purpose of the study. Generally we can point out them briefly by following methods.

Manual collection with a pair of fine forceps.
Manual collection with a fine pointed (No.0) paint brush.
Baited trapping.
Pitfall trapping.
Quadrat sampling.
Special sampling methods for the leaf litter associated ants.
i. Litter lifters
ii. Winkler sack
iii. Berlese funnel
Intensive sampling of ants.
Sampling methods for arboreal ants.
i. Sweeping vegetation with insect nets.
ii. Beating vegetation with stick or shaking branches of trees vigorously to dislodge ants onto sheets or trays.
iii. Setting up of sticky traps to capture ants.
iv. Manual collection of ants on vegetation.

*images from wikipedia

2011-02-24T04:49:00.000-08:00

Let’s talk about insects

We live in a world of insects. Close to one million different species of insects have been identified (compared to only 4,000 or so mammals). That makes insects the most abundant group of creatures on earth. They are found all around the world. One acre of ground may be home to more than a million insects!

Insects are part of a large group of animals called invertebrates. Invertebrates do not have a spine (a backbone). Instead they have an exoskeleton -- a hard outer shell that protects them.

All insects have 6 legs. Spiders aren't insects, they're arthropods. You can tell they aren't insects because they have 8 legs.

Most adult insects have three major body parts: the head, thorax and abdomen. The head includes the eyes, antennae, and mouth. The thorax, which separates the head from the abdomen, is where the insects wings and legs are attached. The abdomen is the largest part. It houses the insect's heart, stomach and tubes used for breathing.

http://urbanext.illinois.edu/insects/06.html

Families of Dragonfly

2011-02-18T06:29:00.000-08:00

If you interest to know abot DRAGONFLIES use this like to get information...

http://www.srilankaninsects.net/Dragonflies/Dragonflies.htm

Blue Oakleaf

2011-02-18T06:25:00.000-08:00

If you interest to know about BLUE OAKLEAF butterfly here is the link to you...

http://www.drkrishi.com/blue-oakleaf-butterfly

News of Giant Poisonous ANT...

2011-02-18T06:19:00.000-08:00

Giant poisonous ants trouble residents of Sri Lanka's Matara town

Sat, May 29, 2010, 08:05 pm SL Time, ColomboPage News Desk, Sri Lanka.

May 29, Colombo: Several areas around Matara and Weligama in the Southern Province have been affected by giant poisonous ants.

These ants normally live on trees but occasionally invade houses and make dark corners their habitat. Some people are seriously allergic to their bites. They have complained of paralysis in parts of the body and red patches in the bitten places. Prof. Sriyani Dias of Kelaniya University, Zoological Department says a study will be conducted on these ants.

Medical officers prescribe pain killers and tetanus vaccine to patients with ant bites, said the Medical Director of Matara General Hospital, Samindi Samarakoon.

Agricultural officers are also studying the ants. Local residents note that ant bites of this nature were reported only after the recent floods.

more detail :-

http://www.colombopage.com/archive_10A/May29_1275143723KA.php

Young Biologists Association, Sri Lanka: සිංහරාජ ක්ෂේත්ර චාරිකාව 2010; Sinharaja Field Trip Fauna & Flora Checklist

2011-01-13T03:47:00.000-08:00

Young Biologists Association, Sri Lanka: සිංහරාජ ක්ෂේත්ර චාරිකාව 2010; Sinharaja Field Trip Fauna & Flora Checklist

Invitation

2010-01-17T20:34:00.000-08:00

This is the Sri lanka Young Biologists' Insect Observation group. Come and join with us.