Bug FAQOak Rough Bulletgall Wasp
Disholcaspis quercusmamma
Adults emerge in late fall, lay eggs in twigs, and the species alternates between asexual and sexual generations that produce different galls at different times of year. The galls can exude a sweet honeydew that encourages sooty mold and attracts hornets, yellowjackets, and carpenter ants, possibly protecting the developing larvae.
Source: Wikipedia
How to recognize it
The galls have a soft, velvety surface and end in a pointed tip that looks like a nipple.
Source: Wikipedia
What it eats
The larvae inside the galls can be parasitized by several parasitoid wasps such as Sycophila dubia, Torymus denticulatus, and species of Mesopolobus and Pteromalus.
Source: Wikipedia
Life cycle
Sex determination follows haplodiploidy: unfertilized eggs become haploid males, fertilized eggs become diploid females.
Source: Wikipedia
When you see it
Adults emerge in late fall and reproduce without mating (parthenogenetically). Mated females seek out newly elongated twigs, insert eggs through the bark to reach the cambium, and trigger the formation of the characteristic bullet galls.
Source: Wikipedia
Lookalikes
These galls look similar to those of Disholcaspis quercusglobulus, but can be told apart by their velvety texture and pointed nipple-like tip.
Source: Wikipedia
Where it is found in the US
Recorded in 39 of 51 states and DC. Most records: Illinois, Minnesota, Ohio, Pennsylvania, Michigan, Wisconsin, New York, Virginia.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in Canada; native in United States. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
When do the adult wasps appear?
Adults emerge in late fall and lay eggs without mating.
Source: Wikipedia
How can I tell these galls apart from similar ones?
Look for a soft, velvety surface and a pointed nipple-like tip; other similar galls lack these features.
Source: Wikipedia
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Disholcaspis_quercusmamma
Look it up elsewhere: iNaturalist · BugGuide · Wikipedia
Text written 2026-10-24 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-24.