Insect Gall

In the spring, before leaves are fully developed, insects lay eggs in the leaf or stem of a variety of plants.  Galls are abnormal growths of plant cells that a formed around these eggs.  After a brief period of cell growth, the gall stops developing.  The insect becomes enclosed by the gall and feeds only on gall tissue during its development.  Small holes on the outside of the gall indicate that the adult insects have emerged.  Generally galls do not seriously harm the plant.  If your tree or plant is already unhealthy or under stress, the damage that does occurs can be to a greater extent than that of a healthy plant.  Keeping trees and shrubs fertilized, irrigated, and pruned properly will help keep plants healthy.

After the formation of galls it is impossible to eliminate the insects with insecticides because they are enclosed and protected inside the gall.  Galls that occur on the leaves will drop off with the leaves but those on the trunk or stems may persist for several years.  Controlling galls with insecticides is usually not practical because there is minimal timing to control the adult pest before the gall is formed.