Last fall I had a bunch of them in my storage building. They were in a clump in one corner about the size of a basketball. I talked to an entomologist who told me that it had something to do with pheromones... they're attracted to a spot and bunch up and stay for the winter. I sucked 'em up with the wet/dry vac and forgot all about them. This spring I was cleaning up my truck and emptied the vac... there they were... a little pale and dusty but still alive.