Bug FAQWillow Rosette Gall Midge
Rabdophaga salicisbrassicoides · Order: Diptera · Family: Cecidomyiidae
Also called: willow cabbagegall midge
The willow rosette gall midge creates galls on Salix exigua where it lives together with Formica neoclara ants and Chaitophorus aphids. Its larvae stay inside those galls through the winter and the adults come out in late April.
Source: Wikipedia
Where it lives
Galls and larvae are found on Salix exigua in a mutualistic setting with Formica neoclara ants and Chaitophorus aphids.
Source: Wikipedia
Life cycle
Larvae overwinter inside the galls before turning into adults.
Source: Wikipedia
When you see it
Adults emerge in late April.
Source: Wikipedia
Where it is found in the US
Recorded in 15 of 51 states and DC. Most records: California, Minnesota, Michigan, Wisconsin, Illinois, Montana, Nevada, New York.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in United States. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
Where are the galls of this midge found?
The galls are on Salix exigua where the midge lives with Formica neoclara ants and Chaitophorus aphids.
Source: Wikipedia
Same family (Cecidomyiidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Rabdophaga_salicisbrassicoides
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-25 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-25.