Why are there so many (mostly dead) moths in the Health Sciences Center?

Seriously, just walking through the atrium I saw five. They’re all over the first and second floors (maybe higher, but I rarely go above the second floor.)

They weren’t here three weeks ago, then suddenly they’re all over the place. There was even a dead moth in my office last week.

Where on earth did they come from? I don’t remember seeing a plague of caterpillars previously. How did they get in the building? Is this part of some diabolical plan?