Lately, I have been keeping an eye out for galls, and this is a good time of year to find them. Many gall wasps use the Oregon white oak as their host, so if you want to go hunting for galls, this is a great place to start. Many things in nature are small, especially insects like gall wasps. And honestly, I can’t identify any of the gall wasps themselves, mostly because they are so small and I haven’t spent much time trying to find them. That said, I am getting more into it and starting by finding the weird and wonderful galls created to house and protect these tiny insects as they begin their lives.
Recently, I found this tiny gall growing from an oak leaf and matched it with the hair-stalk-gall wasp found in Ronald Russo’s book Plant Galls of the Western United States. This gall grows along the margins of leaves and forms a smooth, pointed gall that grows from a thin stalk. In spring, the color of the gall starts from yellow to orange and turns beige by summer.
In his book, Russo writes, “These smooth galls are fully developed by April, with males and females emerging between April and June. Galls remain on host leaves until fall, even though the occupants have left. This would appear to be the bisexual generation of an as yet undescribed unisexual, summer-fall generation with its own distinct gall. Common.” Gall wasps are tricky. It appears that its summer-fall generation has not been observed or recorded. It’s fascinating that the second part of the yearly lifecycle of a common gall I can find at the arboretum, is still a mystery. There is so much to discover in our backyards!
Note: I want to go back and take better photos, which I hopefully can do this week, and update these.
Resource
Russo, Ronald A. Plant Galls of the Western United States. Princeton University Press, 2021.
