Gall Insects Several Groups

From: Ostry, Michael E.; Wilson, Louis F.; McNabb, Harold S., Jr.; Moore, Lincoln M. 1988. A guide to insect, disease, and animal pests of poplars. Agric. Handb. 677. Washington, DC: U.S. Department of Agriculture. 118 p.

Importance- Several insects and mites cause swelling or galls on the stems, shoots, leaves, and petioles of Populus. Most galls cause local injury that does not affect tree growth or survival. A few galls cause premature leaf fall or stem breakage.

Look For: Round, oval, or irregular swellings on the stems, shoots, leaves, and petioles.
Leaf Galls.	Stem Galls.

Biology- Galls are caused by various organisms such as aphids, midges, flies, and mites; each organism has a specific life cycle.

Monitoring- Check trees for galls. Consider control only if the pest is killing shoots or trees.

Control- Seldom recommended. If control is needed, identify pest and follow control recommendations for it.
Leaf Galls.	Petiole Gall.