CATERPILLAR OF THE WEEK: IDIA PART 3: LURKING WITHIN
We estimate that our Idia litter moth caterpillars number in the hundreds, but we've only found a couple pupae and one adult moth so far. Why is that you ask? The age variation definitely plays a part, but our Idia are also sharing their home (and bodies) with some unwelcome house guests.
There are at least TWO species of parasitoid that we've seen so far attacking the growing Idia on two fronts:
1.) Parasitoid wasps in the family Braconidae (pictured below) laid eggs in some of the caterpillars. A wasp larva will hatch INSIDE THE CATERPILLAR then eat it from the inside out, eventually emerging from the abdomen of the caterpillar to form its cocoon and pupate while still attached to the leftover larval husk. The wasp pictured below is slightly smaller than a grain of rice.
2.) Unseen (for now) parasitoids are also affecting the Idia pupae. In the pupae images, you can see at least 6 exit holes from this one individual! This is most likely an even smaller parasitoid wasp that laid eggs in the caterpillar, then waited for the caterpillar to pupate before finishing its life cycle by consuming the developing pupa and chewing their way out.
These Idia are facing some pretty unfavorable challenges (understatement of the century), but often in nature shear numbers can play a part in successful growth and reproduction. What would you do if you were in their position?