Some Miscellaneous Green Caterpillars for St. Paddy’s Day
Happy St. Patrick’s Day! Today of all days we obviously need greenness, so here I’ve got your green caterpillars! Of course, green caterpillars are very, very common and come in many species that all look a lot alike, so I don’t have much idea as to what any of these are.
This could possibly be the caterpillar of one of the many kinds of little orange butterflies that live in our yard. Or, it could be something else.
I expect it is some kind of owlet moth, but even though I have this massive tome to search through, there are just so many green ones that I can’t decide.
And here are some green “mystery eggs” that were on the outside of one of our windows on July 3, 2011. They later hatched out and dispersed while we were out of town for a couple of days, and I therefore missed trying to raise them up. I bet the baby caterpillars were green, though.
I really doubt that it was trying to eat her hair, but one never quite knows. I expect that it rappelled down onto her head at some point during our walk in the woods earlier that day.
In the spirit of clearing out long-standing backlogs, here’s an unknown green inchworm that has been in my files ever since June 3, 2009, and was photographed with my old camera:
And, finally, this one is a brown-and-green specimen from July 31, 2010. While it isn’t the lurid uniform green of the others, it still has green patches. And it looks to be immature, and is therefore probably as unidentifiable as if it were uniformly green:
Immature caterpillars are particularly troublesome to identify, because for a lot of moth species there is no complete photographic record from egg to pupa. What photographs do exist are most likely to be taken when they are at their biggest (and therefore just before pupating), because the bigger caterpillars are easier to spot, more likely to be collected by beating around the bushes, and are more likely to be prowling around off of their food plants looking for a place to pupate.
There. Is everybody all caterpillared-out now, with a surfeit of greenness? I could keep going with a bunch of unidentified cutworms that I have in the files, but those are all brown and gray, so they need their own posting. Anyway, if anybody recognizes any of these little guys, I’m all ears.
 Sadly, St. Patrick doesn’t actually have any connection to insects. With him, what we’ve got for associated wildlife is snakes. Still, snakes are cool, too. And I suppose that caterpillars are sufficiently snakelike that we can kind of shoehorn them in under the “snakes” thing. Particularly if they are green – St. Patrick definitely goes with green. Now I wish I had some pictures of a green caterpillar eating a shamrock (or at least some clover). That would definitely do it.
 If you sing The Unicorn Song and replace “green alligators” with “green caterpillars”, it still scans perfectly and makes just as much sense. In fact, it might make more sense, because alligators are more of a dark brown to gray color, and any green on them looks to be more due to algae growth than inherent color. So now it’s gotten to the point where whenever I think to myself “green caterpillars”, my brain then runs off into “and long-necked geese, some humpty-backed camels, and some chimpanzees . . .”
 Green pigment in caterpillars often is a close color match for chlorophyll from plants, and for a long time it was thought that they actually extracted chlorophyll from their food plants, and transferred it into their skins. But, studies of the actual chemical structure of the pigments showed that it is actually insectoverdin, made from a mixture of blue pigments (usually mesobiliverdin, produced by the caterpillar), and yellow carotenoids (which they evidently get from the plants they eat, since animals normally can’t produce carotenoids). This means that by varying the diet of green caterpillars, it is often possible to make them bluer (by giving them low-carotenoid foods) or yellower (by increasing their carotenoid intake).