For the history of this cutworm, please see Cutworm with Parasitoids – Intro.
The movement of hundreds of parasitoid larvae within the cutworm were slight, and barely noticeable to the naked eye. Under magnification – and with a timelapse effect – the movement becomes more obvious. Pay particular attention to areas such as the head, mandibles and legs.
So how did this caterpillar become literally stuffed with parasitoids? Was it a single parasite or many that laid all the eggs it must have taken to produce so many larvae? This species of cutworm has been parasitized by Copidosoma bakeri (Chalcidoidea: Encyrtidae), a parasitoid wasp that actually lays only a single egg in the cutworm. This one egg produces multiple embryos (called ‘polyembryony‘) that can produce over a thousand young! The larvae not only consume this cutworm from the inside, they also make it feed longer and grow bigger so that it can allow the growing parasitoids to develop fully. And to think that the adult wasp can go on to lay hundreds of eggs in hundreds of other cutworms makes this type of reproduction even more amazing: a single 1 mm long parasitoid wasp has the potential to create hundreds of thousands of offspring!
Here is a sequence from a week later. Activity has almost stopped completely, and the cutworm is beginning to darken and shrivel. Are the larvae pupating?
Another week passes. At this stage I am wondering if the cutworm has dehydrated too much, killing the larvae.
However, a few days later, some stirring within the mummified corpse…
Coming soon: Emergence!