Gall Wasp

Gall wasps are small wasps of the family Cynipidae whose larvae induce abnormal, often colorful growths called galls on the leaves, stems or roots of oak trees and other plants by chemically manipulating the plant's own tissue to form a protective and nutritive chamber around the developing larva. Many species have complex life cycles alternating between sexual and asexual generations that can produce differently shaped galls on the same tree, and the high tannin content of some oak galls made them a historical source of iron gall ink.