Poplar Petiole Gall Aphids
Pemphigus populitransversus
11 host plants
Last updated
Look for hard, pale green swellings along the leaf petioles or midribs of black cottonwood and trembling aspen; mature galls appear rounded and tightly enclose small grayish, waxy aphids inside. These galls develop in early summer as aphids feed on petiole tissues, with damage mostly cosmetic on poplars themselves. The pests are distinguishable by short antennae and undeveloped cornicles.
Poplar petiole gall aphids migrate to herbaceous hosts like lettuce and beet in midsummer where they cause root damage. Focus monitoring on summer vegetable hosts if grown nearby. Remove heavily infested leaves, or tolerate minor cosmetic damage on ornamental poplars. Chemical intervention is seldom needed for this pest.
Quick Reference
All these aphids are light green in color. Spirea aphid is very difficult to separate from apple aphid without high magnification, whereas apple grain aphid can be distinguished by a yellowish green stripe down the middle of the back. Apple grain aphids infest pear only in the early part of the season, while apple aphid is present all summer. Aphids suck plant sap and live in colonies on new shoots. Populations are damaging only sporadically. Damage appears as rolled leaves, stunted terminal...
Cultural Controls
- Hose aphids from trees in fall with a strong stream of water.
- Natural enemies of aphids such as ladybird beetles, syrphid (hover) flies, green lacewings, and others help control aphid populations.
- Avoid use of broad-spectrum insecticides which kill these beneficial insects.