Massive aggregation found starving on sidewalk, I guess Oedemasia is having a population explosion right now. Accepted apple foliage and later fed entirely on rose foliage without issue, and did not secrete very much silk when walking (even after I fed them copiously), unlike . The rose bushes in question were actually pretty near the animals' presumed points of origin were and also pretty big and lush, but had no preexisting eggs on them so maybe adult O. salicis hate ovipositing on roses. I suspect that this brood was instead oviposited on a walnut tree.

I noted no interesting social behaviors, and only one visible communicatory behavior (others surely exist but are presumably chemical instead of behavioral). Namely, the larvae scraped their mandibles sideways back and forth across the leaf seemingly to repel other larvae touching them (this was noted in both early and late instars, and even in specimens inactive due to premolt), and if sufficiently perturbed would bend their heads towards the intruding larva, but I saw no actual violence and these displays often failed to repel the intruding larva (but occasionally frightened them away). They also got into "traffic jams" often. Any gregarious tendencies they had immediately broke down in captivity as the slippery main stems and thin petioles of rose made it difficult for specimens to be near each other, and they did not display any obvious distress or detectable attempts to regroup in any instar. If anything, the "traffic jams" interfering with feeding stressed them out more (I soon realized I had to provide them with more foliage than they could eat in order to space them out. They still showed no detectable attraction to each other then, and seemed unable to lead each other to food).

Most of this batch of larvae were similar in color to each other. The dark morphs were relatively uncommon. Larger img here.




Update 10/27: after being fed on a steady diet of rose, one of the last few specimens that had not cocooned was visibly reluctant to eat apple again, attempting to abandon the leaf after a few bites.