Aceria neoessigi (Keifer, 1940) (Eriophyes).

Mites overwintering in the buds of Populus emerge in the spring to attack the flowers of the catkin. Attacked flowers become malformed and enlarged and group tightly together such that the catkin forms a large pendant gall that may exceed 20 cm in length (Fig. 18). Galled catkins remain on the tree until early summer, long after unattacked catkins have dehisced. The species does not have a secondary host. Galled catkins may also contain Aceria populinquis Keifer, which occurs as an inquiline (Wilson and Oldfield 1966). In the United States, P. fremontii is the primary host (Wilson and Oldfield 1966). In Canada, the primary host is P. deltoides (KF, pers. obs.), which is closely related to P. fremontii (see Fig. 6 in Eckenwalder 1996).

- Kevin Floate: (2010) Gall-inducing aphids and mites associated with the hybrid complex of cottonwoods, Populus spp. (Salicaceae), on Canada’s grasslands^©