Poplar Twiggall Fly

The Poplar Twiggall Fly (Rhabdophaga strobiloides) is a species of gall-forming insect that affects various species of poplars and cottonwoods. The adult female fly lays its eggs on twigs, causing the host plant to produce abnormal growths, called galls, around the eggs. The larvae feed on the interior of the galls and pupate inside. The galls typically resemble small, rounded, green-brown growths on the tips of twigs. Heavy infestations of Poplar Twiggall Fly can result in a reduction of twig growth and potential damage to young trees, but the effects on mature trees are typically minimal. In some cases, the galls can cause the affected twigs to break off. Management options for Poplar Twiggall Fly include removing and destroying heavily infested twigs, applying insecticides, and promoting healthy tree growth to help trees better withstand infestations. In many cases, natural enemies, such as parasitoid wasps, help to keep populations of Poplar Twiggall Fly in check, reducing the need for additional management. As with many gall-forming insects, the galls themselves do not typically cause serious harm to trees and can even provide habitat for other wildlife. Poplar Twiggall Fly is a relatively minor pest in most areas, and control measures are usually not necessary.