Saturday, 23 April 2016

Caterpillar with a Problem

On 11 April 2016 while doing some night photography in the bush on Clohesy Road, nr Koah, Queensland, we discovered a caterpillar with a problem.
This caterpillar, probably a lymantriid, Euproctis, perhaps lutea, had been parasitised by a small wasp early in its life history. The white pods are cocoons of the wasp, not eggs. The eggs had been laid internally by the wasp a couple of weeks before and the larvae developed within the caterpillar feeding on substances in the body fluids of the host.
 The unhatched cocoons with caps intact.
 Three days after collection of the caterpillar, the wasps emerged leaving the empty cocoons.  The parasites are wasps of the family Braconidae, probably in the genus Apanteles. The caterpillar remained active, moving around until 22 April, 2016 when it died. It had been doomed and would never have been able to form a cocoon and become an adult moth. This is an example of natural biological control

The caps indicate the hatching of the cocoons. There were 13 female  and 4 male Apanteles wasps.
The wasps. The female is in top. Note the short ovipositor that is used to insert eggs into the host caterpillar.

1 comment:

Scott Ritchie said...

This brings back memories of my childhood in Iowa. We had a catalpa tree next door that was often host to hundreds of black and yellow catalpa sphinx caterpillars. I collected and tried to rear some out, but within a few days, they were all encrusted to braconid cocoons, and subsequently died.

Lots on the web about this interesting caterpillar and its parasitoids.