Friday, 17 September 2010

Life Cycle of the Three-spot Grass Yellow (Eurema blanda)

Apologies for the long delay in posting. This time though, I have the entire life cycle of the Common three-spot yellow butterfly (Eurema blanda) in photographs.


The female lays large clutches of eggs on the host plant.


The host plant in this case was the Cassia fistula or the Golden Shower Tree.


The eggs hatch within a week. Sometimes in as few as 3 days.

All eggs hatch one after the other and soon after the caterpillars feed on what is left of the egg-shell.


They usually remain on the leaf on which they hatch on and begin to feed on it.


This species lay so many eggs because the caterpillars appear to be highly edible and are easily picked off by birds and other predators. More numbers give it a better chance of propagating its species.


The caterpillar undergoes several successive moults as it grows older, shedding its old skin for new ones. It picks up more colour as new moults happen.


Soon, it is time to pupate and the caterpillar stops feeding and  becomes restless as looks for a suitable location where it will pupate.


In this case it has chose a nylon twine on which to pupate. Pupation may also occur on plants and dried twigs.


The caterpillar then attach├ęs its posterior end to the twine via an apparatus called the cremaster,


It also spins a web around itself to create a saddle on which it hangs.


Once set in this position, the caterpillar’s head splits open and the pupa begins to emerge.


It sheds its old skin with a wriggling motion, exposing the soft pupal form within.


Once fully emerged, the pupa waits with minimal movement ……….


…as its skin slowly but surely hardens.


The colour too changes over 24 hours ass it loses the transparent form to become more opaque.


The colour continues to change over the entire pupal period which may last more than a week and just before it hatches, the black of its upper forewing will show through the pupal case to give the pupa a black and yellow colour.


The pupa then splits open to reveal the image, as it crawls out with folded wings.


The imago then discharges a droplet which is called the meconium. This is its metabolic waste that has accumulated during the pupal stage.


The imago then spreads its wings by pumping its blood into the wings.


as the wings straighten and harden, the butterfly takes on the beautiful shape that we all know and love.


Soon it is a fully formed adult that is ready to fly off and feed .


It soon finds a mate and mates with it….the female is then ready to find its host plant, where it will lay its eggs and begin the whole life cycle again.


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