Actually, they look pretty cute in the photo. This is because you can't see them TWITCH! Though I find many things in nature scary (see blog title), few things truly make my skin crawl. Tent caterpillars are one of them.
Do you have them where your are? I sincerely hope not. Malacosoma californicum all live together in a big web nest. We've had so few in the past several years I had forgotten about them. The nests can grow quite large, engulfing whole branches. The webbing of the nests is disturbing, recalling Mirkwood and large bodies running through the tree tops.
But that's not the creepiest part. They twitch when they feel threatened and it looks synchronized, almost as though they were all controlled by one big brain. AHHH!
I saw these on rugosa bushes in a store parking lot. I do hope we won't have any in the Scaredy Cat Naturalist's yard. They would tax my wildlife sanctuary sensibilities. So far the only creatures not welcome here are fleas and mosquitos.