Wasp galls - Druon ignotum

Moved

… Adam Kranz, 24 January, 2023 - 12:10am

possibly...

If the oak is Quercus macrocarpa (per John & Jane's comment under the leaf photo), then the larger fuzzy gall is likely Acraspis villosa. I looked this up in Cynipid Galls of the Eastern United States (Lewis H. Weld, 1959) and Plant Galls and Gall Makers (E.P. Felt, 1940). The only online information I could find on Acraspis villosa is here, where it says that the gall occurs on the top of the leaf. But both Felt and Weld say that the gall occurs on the midrib vein on the underside of the leaf (like the one in your photo). The species is listed as occuring on burr oak by both Felt and Weld. There weren't other galls that matched as well (Weld lists galls by the species of oak on which they occur), though knowing how many larval cells were under all the fuzz would help eliminate one other possibility. I'm assuming there were only 1 or 2 larval cells in the fuzzy mass.

Someone who really knows the oak galls of Wisconsin would have to confirm before moving this to a species page... if it's possible at all to be certain of species with just the one photo.

… Joyce Gross, 2 October, 2007 - 2:32pm

wasp galls

You have two species of wasp galls in this photo -- the larger fuzzy one on the right, and the smaller ones on the left. The family is Cynipidae for the one on the right and probably for the ones on the left as well. I don't know Wisconsin cynipids (I know some of the California species) so I won't guess which species they are.

Do you know which species of oak tree these galls were on?

… Joyce Gross, 1 October, 2006 - 12:14am

Thanks for the information on

Thanks for the information on the Cynipidae. I will post another photo with the oak showing the leaves. Sorry I'm not sure what type of oak it is. I checked today and other leaves also have the fuzzy galls although none are as big as the one pictured.

… Ilona L., 1 October, 2006 - 10:19pm

Your oak

isn't one I know that grows here in the Bay Area, so that confirms that I have no idea as to the species of wasp. I just posted similar looking gall here that I did identify to species with the help of an expert. Cynipids are particular about which trees they lay their eggs on -- I've been photographing lots of galls lately, and it's clear that these wasps know oak trees better than I do.

… Joyce Gross, 2 October, 2006 - 2:10am