On Black Cherry (Prunus serotina). The Black Cherry Gall Azure Caterpillar mimics the Black Cherry Leaf Gall (Eriophyes cerasicrumena). The galls are home to small mites that feeds on the black cherry leaf. It turns out this caterpillar has a fondness for the galls - it eats the galls, mite and all. It’s one of only two caterpillars in our area known to be carnivorous. (The other is the caterpillar of the harvester butterfly.)