Saturday, February 18, 2017

It's Not Fruit; It's Manzanita Leaf Gall Aphids

Yesterday this came into my office:

Fruit-like galls on the newer leaves of a manzanita. 
It's a Manzanita (Arctostaphylos) with what look like berries or peppers growing near the top of the plant. Turns out they are the handiwork of the manzanita leaf gall aphid (also called the manzanita leaf-fold aphid), a plant juice sucking insect that injects just the right mix of plant-hormone like substances into the manzanita it's feeding on to cause the leaf to pucker up and color up and look just like a fruit. This protects the aphid from predators and doesn't seem to hurt the manzanita much. It is caused by animal browsing, pruning or fertilization as the soft new growth that follows any of these actions is highly susceptible to infestation by the aphid. 
Manzanita leaf gall aphids visible after dissection of the gall with a razor blade.

Manzanita Leaf Gall Aphid Links

Manzanitas - UC Master Gardener Program of Sonoma County
Red Leaf Galls on Manzanita in Arizona's Sycamore Canyons
Manzanita Leafgall Aphid (Tamalia coweni) ·
Pseudo-peppers, Manzanita Leaf-gall Aphid (Tamalia coweni) - The Firefly Forest
Pests of Landscape Trees and Shrubs, Third Edition: An Integrated Pest ... - Google Books
Manzanita Leaf Gall Aphid - Tamalia coweni - BugGuide.Net