Family Cynipidae - Gall Wasps

Gall wasps

Cynipidae Latreille 1802

>750 species in ~50 genera in our area(1); >1400 described spp. in 74 genera total(2)

2-8 mm

First segment of hind tarsi about as long as following two or three combined; most species humpbacked; abdomen with two segments visible dorsally, the remainder telescoped beneath.

Succulent spring galls on oak buds, flowers, and leaves produce fully winged, short-lived males and females. The larvae in the more solid, autumnal galls metamorphose in the fall and depending on species the adults, which are all agamic females, may emerge in late fall (as in Disholcaspis spp.) or stay in the galls over the winter. Often two or more winters pass before the adults finally emerge.(3)

It may be the normal reaction of the host to the stimulus of a cynipid or it may be quite abnormal if it has been modified in size and structure by the attack of guests or parasites in its early stages. Only if found in numbers and on several trees is it probably the characteristic work of a cynipid and worth collecting and rearing.(3)