- Stout pouch galls on leaves
- Yellow to red pouches on leaves
On elms, yellow pockets of leaf tissue grow out of the top of the leaf surface on a narrow stalk. In time, galls grow up to 3/8" long. When they turn red, they resemble the cockscomb of a rooster. Galls can't be removed without ripping leaf tissue. Large numbers of galls are unsightly. If leaves are heavily infested, the flying aphids may become a nuisance. This pest is generally not considered a threat to plant health. Other galling aphids that produce large hollow pockets in leaves include the Witch Hazel Cone Gallmaker, Hormaphis hamamelidis.
In the spring and early summer, they feed on elm leaves and form galls. Later in the year, the adults fly out of the galls and feed on grass roots.
These galls do not threaten plant health and only have a minor impact on plant appearance. Gall makers have many parasites that eventually reduce their number. Control is not warranted.
Pesticides are neither available nor recommended for managing this pest.
