insect galls on oak leaf
When insects lay eggs on leaves, little bumps called galls swell up
all around the eggs.
Why some leaves have bumps
Sometimes, the leaves or stems of plants become spotted with little
greenish or yellowish-white bumps. These bumps are called galls. They
are often made when an insect lays eggs on very young stems or leaves.
The insect eggs cause a change in the growing plant. The change makes
little swellings grow up around the eggs.
Some galls look like beads, some look like marbles, some look like balls
of pink cotton. The shape of a gall tells what kind of insect made it.
The baby insect is protected by having the gall around it. And the baby
insect uses the inside of the gall for food.
