Thursday, 23 September 2010

Life Cycle of the Common Crow Butterfly (Euploea core)

DSC03116

The Common crow (Euploea core) is a common butterfly found in South Asia. It is a black butterfly with brown undersides with white spots and markings along the margins of the wing undersides.

Common crow (Euploea core)

It’s life cycle begins with the female laying eggs on the host plant. This butterfly has a variety of host plants. In this case it was a Oleander plant.

Common crow egg

The egg is laid singly on the under side of the host plant.

DSC03114

Young leaves are almost always chosen on which to lay eggs.

SONY DSC

The egg is tall and pointed, with ribbed sides. It is a shiny white colour.

SONY DSC

However, as the egg matures and is about to hatch, the top of the egg becomes black, with the rest of the egg showing a dull grey colour.

DSC03321DSC03267

When the egg hatches, the caterpillar that emerges is a small white creature with black head and black feet.

DSC03271

However, as it begins to feed, the colour begins to change.

DSC03469

The caterpillar takes on a brown colouration with greyish stripes. Also, spiny extensions on its body start to grow in prominence.

DSC03061

As the caterpillar continues to eat, the colouration becomes more bright with white and dark black/brown alternating bands; and the extensions also lengthen.

DSC03059

These extensions curve backwards at its tips.

DSC03054

A noticeable feature of the caterpillar is that it always stays on the underside of the leaves.

DSC03064

The caterpillars themselves are toxic as they are able to accumulate the toxins from the host plant into its own fatty tissue.

DSC03058

Since the leaves themselves are toxic, the caterpillar has designed a clever way in which to feed on it. It first chews the midriff of the leaf, cutting off the supply of the plants poisonous latex to the leaf. It then nips the secondary veins, further restricting the flow. It then feeds on regions of the leaf where the plants natural defences have been shut off.

DSC03063

Shown above are the droppings of the caterpillar, produced as it continually ingests leaves and ejects these pellets as biomass.

DSC03150

As the caterpillar grows, it continually moults and sheds its old skin as it grows bigger and becomes restricted within the old skin.

DSC03148

Finally, it is time for pupation and the caterpillar ceases feeding and chooses a leaf on the host plant itself, on which to pupate.

DSC03194

It attach├ęs itself by its posterior end ( via a cremaster apparatus) to the leaf and hangs upside down.

DSC03272

The skin then splits open to allow the pupa to emerge from within.

DSC03291

The old caterpillar skin is shed as the pupa twists about its cremaster.

DSC03298

The pupa then hangs to dry as it slowly begins to resemble a finished pupa.

DSC03320

The final form is shown below:

DSC03339

However, it picks up markings and colouration changes throughout its pupation period.

DSC03435DSC03438

…growing darker and taking on a dark metallic sheen as it ages and matures.

SONY DSC

…before it finally emerges into a fully formed adult butterfly.

Common crow (Euploea core)

The adult Common Crow is toxic and unpalatable to predators, attributing for its slow careless flight. Hence it becomes a model for other species of edible butterflies to mimic. This form of mimicry where an edible species mimics an inedible species is called as Batesian mimicry.

Common crow (Euploea core)

The Common Crow is mimiced by the following species of butterflies.