While iNatting the greenways today, I found a rolled leaf on an otherwise bare branch of a hornbeam. Because the leaf was dried up, I suspected that it was a pupation shelter rather than a feeding shelter, and so I didn’t want to risk opening it.
Gemini was no help in identifying it – for “hornbeam leaf roller,” it only suggested European species, two beetles and a moth. On BugGuide, I found a reference to a “hornbeam leafroller,” but that feeds on the hophornbeam, a tree in a different genus.
I carefully brought the rolled leaf home to wait for the imago to eclose; but since I didn’t open it, I don’t know if there is actually a pupa in it. How long should I wait before giving up and opening it?
I’d assume that if it is a leaf roller, there should be a smooth brown pupa just resting in the curled leaf, so very gently opening the leaf shouldn’t hurt anything, especially since you’ve already collected it.
I have the same question. I found a caterpillar on July 13 that I believe is an Impressive Dagger Moth, Acronicta impressa. It fed on willow (Salix sp.) leaves and on July 20 it rolled itself up inside a leaf. But I don’t know how many generations this species goes through in a year: I live near Fairbanks, Alaska so if it’s just one generation I’ll have to wait almost a year to see the adult and I’m not sure what conditions it needs: above or below freezing? Some butterflies in my area produce 2 generations: the 2nd generation overwinters as an adult. This 2nd generation of Morning Cloak and Compton Tortoiseshell Butterflies is coming out now, so we’ll see!
So, I finally did this last night, and there was no pupa. I’m not even sure it was a leaf roll – it looked like the inside was wood fibers. So that opens up a whole new mystery: what looks like a leaf roll, and hangs on a twig like a leaf roll, but is woody inside?
I think some spiders make leaf rolls, and I think other organisms may move in if the caterpillar has gone. I’ve seen tree crickets and beetle larvae in them. You have a lot of potential options…
