What a day yesterday was. After attending a conference all day in downtown Cincinnati, I hustled off to meet one of Ohio's preeminent herpetologists. He showed my what is now the Queen City's most famous reptile, and I've got photos of that excursion to share later.
Following that, it was off to Adams County and the Edge of Appalachia preserve for an 8 pm meeting. Why so late? Caterpillars. We had enticed a major newspaper to do a story on caterpillars and their importance to the environment, and as most caterpillars are active nocturnally we had to adopt an owl's schedule. Thanks to whiz-bang naturalists John Howard, Rich McCarty, and Mark Zloba for agreeing to help the reporter and photographer find some cats and learn about their fascinating habits. I'll share more about the article once it emerges.
As you've noticed, this silky cat is heavily beset with long setae, or hairs, and looks like a tiny, tubular Pomeranian dog. There are probably two primary reason for all of the "fur". One, it makes it tougher for birds to snack on Apatelodes, as all of those bristles are unpalatable and it's just not worth the bother for most bird species. Two, all of the hair may make it tougher for the parasitoid insects - flies and wasps - to get at the caterpillar's body and attach their eggs. And as we shall see, the latter fate is a caterpillar's worst nightmare come true.
The female wasp has a long stingerlike ovipositor, and she uses it to inject eggs on or into the tissue of the caterpillar (or other insects, depending on the species of wasp). Along with the eggs comes a special cocktail known as a bracovirus, which serves to infect the caterpillar's immune system and mask detection of the invading eggs. Once the wasp grubs hatch, they begin feeding on non-vital innards within the caterpillar - eating it alive, essentially. It is in the wasp grubs' best interest to keep the caterpillar alive as long as possible, so they have fresh food to see them to maturity, and also a living caterpillar is better able to hide and avoid other predators such as birds.
Finally, when all is ready, the wasp grubs burst through the skin of the caterpillar and form the cyclindrical little coccoons that we see in these photos. Amazingly, this caterpillar was still alive, although barely. Perhaps even by now, a day later, the wasplets have emerged from their coccoons, leaving the dried husk of the sphinx caterpillar. A seemingly terrible fate, but one shared by scores and scores of caterpillars.