Question
Hi, Jim:

We live in Southeast Michigan. We have a big tree in the front garden. Now it has some insect problem. We found lots of green "balls" on leaves. The green balls are about the size of a small cherry. Inside these balls are worms. These worms/balls apparently eat tree leaves. There are also lots of white dots or holes on leaves. Could you identify what kind of bug it is and how to deal with it? Thanks.

Jenny

Answer
Strange bumps or growths often appear on leaves of trees and shrubs. These are usually leaf galls. Although they may look like a serious problem, most are harmless to the overall health of the tree or shrub.

Leaf galls are fairly common on trees and shrubs. A gall is actually plant tissue that has developed as the result of feeding or other activity of insects or mites. Plant hormones are involved when the pest interferes with leaf development in the spring.

Once the gall appears on the leaf, there is no way to control it. Preventing most leaf galls is extremely difficult. However, other than being unsightly, most leaf galls are not harming the tree or shrub.