Handling the tricky stuff

Handling the tricky stuff

Friday, August 3, 2012

The Caterpillars Have Hatched and They Look...

Awww... cute? Really, somewhat badass. Like they want to be punk rockers when they grow up.

Honestly, I can say that regal moth caterpillars have more "hair" (actually, they are spines) per body mass than any other creature I've ever seen. They are about 1/3 an inch long(say a little over 1 cm, if we go metric -- the largest just-hatched caterpillars I've ever seen too) and about a third of them is spine.

Why they would evolve to have such a bizarre body at hatching is anyone's guess. At this size, "protection" seems pointless, and this is an huge encumbrance, not to mention a waste of resources. I guess the "designer" wasn't so smart on this one.

Anyway, I have them started on a foodplant -- sweet gum. This is going to be my primary foodplant for both the regals and the lunas, since I have a lot of it in my yard, with plenty of branches that are within reach. I'm also going to do a little experiment, feeding a small number of the regals pignut hickory instead, but more about that in my next post. Both luna regal moths eat pretty much the same trees (a lot of different nut trees and others with aromatic leaves...) though regal has the bigger palate.

I'm going to "sleeve" these caterpillars outside soon, but when they are this small I don't want to lose any, so I'm starting them on potted saplings inside. I've made a tube of nylon screening that I can put over the plant and tie at the top for easy access. This allows the cage to "breathe" and hopefully will keep the babies from drowning in condensation drops or getting mold. A lot can kill you when you're little. I'll lose some anyway, but with any luck, not too many.

Giant silk moth caterpillars (and most large moth caterpillars) grow in five stages ("instars") and sometimes radically change in appearance each time they shed and enter the next stage. In some species (not in this one, I think) there can be a lot of variation in coloration (for example, some can be green, some can be red, some can have stripes, some just a few spots) even within the same group of eggs from the same mother -- variation that is much rarer in the adults. Why? Again, who knows. It's a mystery I may speculate on later. It's a topic I've never heard entomologist talk about much.

By the way, another strangeness with these bugs: A group of them hatched VERY rapidly. I looked at the eggs and none had hatched at about 9:10 this morning. I looked again just a little before 10 and there were a couple of dozen crawling around. The eggs were not laid very simultaneously, so hatching must be triggered by some kind of environmental factor -- light? Anyway, interesting. I notice that there seem to be big groups at different (but similar within the group) stages of development (judging by color).

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