Sagebrush Gall

A gall  is a grape-like growth on a sagebrush. 
Some are round, smooth and reddish, other are covered with a mass of white hairs. Some are dried and shriveled up, with a tiny hole visible. Each is gall: a tumor-like growth of plant tissue triggered by an insect. The plant gall grows quickly in response to an invading insect, providing it with all needed water, food, and shelter, usually without causing harm to the host plant. Galls are often specific in shape, color, and size, so an observer can identify the kind of gall-inducing insect just by looking.