Who creates galls?
Most directly, plants grow galls, which are made out of their tissues. However, the intruding organism triggers and sometimes directs the growth of the gall. Galls may therefore be thought of as collaborative projects. Generally speaking, galls are not harmful to plants. As is true for all parasites, gall-inducing organisms depend upon the existence of their hosts, so it would be counterproductive for them to cause significant damage. Galls can weaken a plant if they are overabundant, but such overabundance is rare and may be interpreted as a breakdown in the normal host-intruder relationship. Great galls Some of the biggest galls are commonly found on oaks in the United States: oak flake galls and gouty galls. Both kinds of gall are induced by small wasps. The wasps that create these galls are called cynipids. They have complex life cycles which involve two sorts of galls. In the spring, the female lays her eggs on oak leaves, producing small galls near the leaf veins. In the first ha
