I’ve been looking for you
I was really hoping to get Acronicta hasta eggs this summer. I missed the first brood, but there should be another round of mating/egg laying this summer. That’s the nice thing about Acronicta, most of them have two broods per year. It’s a nice safety net if I mess up the early spring window for collecting.
Two weeks ago we came across this big guy… Acronicta hasta. There is no way this species should be in its final instar already! The female must have emerged in April when we had some of those crazy warm days… and somehow the caterpillars managed to survive a long stretch of cold nights with only a little vegetation starting to grow.This might explain why some species were hard to get this spring – the strange weather threw off a lot of insect life cycles.
The early instars are all green with a red stripe down their back. They sit on the upper surface of leaves, flaunting themselves to birds. It is not know if they are chemically defended, or if the red stripe serves as aposematic warning coloration. They feed on cherry, which is not exactly a poisonous plant. This is why I would love to experiment with them! A study by Singer et al. (in press) has shown that birds tend to leave this species alone.
The last instar, however, is black with yellow spots and a maroon red stripe down its back. It prefers to rest on twigs or bark, as seen in this photo (this was its natural resting position when we found it):
And here it is in the sunlight:
Since this species burrows into wood to pupate, it makes sense that they would don a darker appearance – you probably do not want to be a bright green caterpillar on bark. If they are really only bluffing with their red warning stripe, it would be a good idea to try hiding some of the time.