Most of the Imperial Moth caterpillars are now two weeks old. Judging by the differences in their size, it's clear that they didn't all emerge from the eggs at the same time. In fact, some were still emerging when I got home from Buffalo, meaning they took at least a week before they all hatched.
Of the estimated 125+ caterpillars, only about 10% survived. We provided them with one food source, since that would keep it easier for us. Though they have many different leaves they will eat, once they glom onto a certain type, they prefer not to change their diet. We chose Sweet Gum (Liquidambar) because we have one right outside our family room. Fast food for caterpillars!
The cats are eating so much now and growing so quickly! Their frass (that's poop, for those who didn't know) started out as a fine powder. It's now about as big as the eggs were (1-2mm). I have to clean the bowl of it every day and I can see it will soon be a twice a day job. Their appetites are ravenous!
I really don't know which instar they're in right now, as I've not seen them as they shed their skin, but most are certainly in their second and likely some are in their third. There are two forms, which become more visible by the third instar - green/yellow and black/orange. These appear to be dark brown so far, so I'm guessing these will be the black/orange, which is the less common of the two forms.
One night, it was very quiet in the house, and I was standing by the bowl. I kept hearing this faint sound and put my ear down by the bowl where the caterpillars were. I could hear them chewing! I watched them for a little while and it was interesting to see how they ate. It reminded me of how people eat corn on the cob. Some of the cats ate in a straight row parallel to the edge of the leaf. Some ate toward the center of the leaf, then came back to the edge and ate another row of leaf material right next to the previous one.
I'd kind of like to keep these inside until they get to the fifth and final instar, just to be able to see them as fully grown caterpillars. They will be about as large as my middle finger! Once they've reached full-size, I'll release them outside, where they'll wander about until they reach soft soil, where they'll burrow down for the winter.
What a life, eh?
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