Petiole galls on Balsam poplar/cottonwood

Galls formed at the base of balsam poplar leaves can be found throughout the state. Within these galls can be found numerous aphids of the Pemphigus genus. They lack the cornicles (terminal abdominal tubules) characteristic of other aphids. When eggs hatch in the spring, these aphids begin feeding on leaf petioles which induces the production of galls that envelopes and protects the developing aphids. As they mature, winged aphid forms will emerge from these galls. While we wait for genetic identification of the species in Alaska, similar species in North America will leave their galls and colonize a different host mid-summer, where they will continue to feed and reproduce throughout the season. By the end of the season, females will return to Populus spp. trees and lay a single egg that will overwinter and emerge in the spring. You can help the Forest Health Protection better understand the range of these aphids by uploading your observations and pictures of these galls to iNaturalist.

Post created by @DanaBrennan

Posted by awenninger awenninger, August 14, 2020 16:01


No comments yet.

Add a Comment

Sign In or Sign Up to add comments