California Caterpillar Craziness!

I couldn't use Stanford in the title because it didn't alliterate as well, but my impression is that this is really only an occurrence on the Stanford campus.

There are caterpillars hanging from the trees by threads of silk! I've never seen this before. They blow about in the wind, and they catch on you as you walk under the trees. They're little fuzzy black caterpillars, kind of cute. Apparently it's the second year that this has happened. I find it very odd that the caterpillars hang from the trees though. I wonder if it's someone's lab experiment escaped into the wilderness of Stanford campus! ;)