Wasp Gall on Rosebush

Observation by Beverly Churchill:

When visiting Denali Park I noticed a wild rose bush near the visitor center. It had the same Rose Rust that my wild roses have developed this summer on my property in Anchorage. But what was strange was one rose bush adjacent to the one with rust had an unusual parasite I have never seen before, so I wanted to report it.

Comments from LEO Editors:

In 2012, LEO received an observation about unusual eggs found on a rosebush. Corlene Rose, with the UAF Cooperative Extension, identified them as spiny rose galls created by cynipid wasps. These galls both protect and provide nutrients to the cynipid wasp larvae as they develop. In the previous post, Corlene writes:

"The gall (plant growth in response to the insect) consists of small hard internal caverns armed with stout, sharp spines on the round exterior. The galls mostly occur on the surface of leaves, but sometimes appear on rose stems. The galls do not appear to harm the plants. Spiny rose gall develops exclusively on wild roses. (There are similar ones on domestic roses.) Many people enjoy photographing and studying these interesting galls."