Gall development is initiated as adults feed on developing buds in spring. The female becomes enclosed in the abnormal growth, and lays eggs within. Eggs hatch and mites reach adulthood and leave the galls rather quickly. These adults may initiate the development of more galls. The gall midge probably has one generation per year, with the winter spent in a cocoon in the soil.
Adults emerge in spring and lay eggs in developing buds.
Though these mites and midge cause galls that may be aesthetically undesirable, they are not a serious threat to the host tree. Handpicking infested leaves, which tend to be most common on lower branches, can help reduce populations. Systemic insecticides can be applied in spring or early summer to kill mites. The Gouty vein midge, a fly, causes pouch galls on the upper surface of leaves along major veins. Drooz, A.T. 1985.