Contarinia negundinis

Callirhytis quercuspunctata (agamic)

Cecidomyia negundinis

Unsightly, elongate, fleshy galls, which more or less seriously interfere with the proper functioning of the leaves, are sometimes extremely abundant on Manitoba maples. This injury is caused by a minute, two-winged fly which lays its eggs in the leaves. When the galls are opened, small maggots, the larvae of the gall-fly, are found within.

Andricus punctatus Bass.

Red oak twigs and small limbs are frequently affected by hard, irregularly rounded swellings from one to two inches in diameter, more or less completely surrounding the twig and often coalesced to form an elongated mass. When very abundant remove and destroy the young galls before the adult gall-wasps emerge. 

The more important shade tree insects of Eastern Canada and their control