280 days of Urbpandemonium #215
Weird growths on plants have always been fascinating to me. I was so happy when I learned that most of them are caused by animals! In this case, a very small fly--a midge called Polystepha pilulae*--laid her eggs in the flesh of this oak leaf. The tiny maggots hatched and began feeding, and the flesh of the leaf hardened around them, protecting them as they ate. Unless they were parasitized by a wasp, they will pupate in their galls and emerge as more tiny long-legged midges.
*Many crowned ball-maker