What is this insect, and what is it doing?

July 19, 2017 10:47 PM

Here's a 1min 30sec video on Flickr. Note that the video was taken sometime in late summer 2016, in Cambridge, MA, right outside of William James Hall.
posted by not_on_display to Pets & Animals (4 answers total)

Best answer: Looks like a bagworm, i.e. a moth caterpillar of the family Psychidae. They build little cases, I guess for camouflage and protection. I’m not familiar with US species but google image search leads me to Thyridopteryx ephemeraeformis as a likely candidate. It’s much bigger than any UK species.
posted by Bloxworth Snout at 11:51 PM on July 19, 2017 [1 favorite]

Actually, I just checked, there are a couple of largeish UK species.
posted by Bloxworth Snout at 11:54 PM on July 19, 2017

Best answer: Yes, some kind of bagworm. What it's doing: Probably it was living in a tree nearby, where its protective 'bag' would be excellent camouflage. Probably it was blown or tumbled out of the tree onto the ground. Then, of course, it tried to climb back up to the leafy safety by climbing the nearest upright object-- which in this case is not a tree. It will probably drop back down pretty soon and try again elsewhere, if it isn't eaten by a predator first.
posted by The otter lady at 8:40 AM on July 20, 2017

Response by poster: Thanks! Never heard of a bagworm, didn't even know they existed. Which means they're doing a mostly good job at hiding. And it is a windy location (15-story building surrounded by shorter structures and trees) so yeah, this all makes sense.
posted by not_on_display at 10:46 AM on July 20, 2017