Oak Leaf Gall Midge

Polystepha pilulae · Order: Diptera · Family: Cecidomyiidae

No source yet on danger. We have no source yet on whether it bites, stings or damages anything.
Oak Leaf Gall Midge
Photo: unknown, CC0

The oak leaf gall midge makes round galls that are about three to four millimetres across. It lives in eastern North America. The galls it creates are thick-walled and reddish-brown.

Source: Wikipedia

How to recognize it

Galls are roughly three to four millimetres in diameter.

Source: Wikipedia

Size

Each gall measures about three to four millimetres across.

Source: Wikipedia

Where it lives

It is found in eastern North America.

Source: Wikipedia

Life cycle

The galls are thick-walled and have a reddish-brown colour.

Source: Wikipedia

Where it comes from

Its range is eastern North America.

Source: Wikipedia

Where it is found in the US

Recorded in 37 of 51 states and DC. Most records: Texas, Minnesota, Massachusetts, Virginia, Ohio, New Jersey, New York, Pennsylvania.

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

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Source: GBIF

More photos

Oak Leaf Gall Midge photo 3
Photo: Clay, CC BY
Oak Leaf Gall Midge photo 4
Photo: Mark Apgar, CC BY
Oak Leaf Gall Midge photo 5
Photo: unknown, CC0
Oak Leaf Gall Midge photo 6
Photo: Brandon Corder, CC BY

Same family (Cecidomyiidae)

Willow Pinecone Gall MidgeWillow Pinecone Gall MidgeRabdophaga strobiloidesGoldenrod Bunch Gall MidgeGoldenrod Bunch Gall MidgeRhopalomyia solidaginisOcellate Gall MidgeOcellate Gall MidgeAcericecis ocellarisLarge Creosote Gall MidgeLarge Creosote Gall MidgeAsphondylia auripilaWillow Rose Gall MidgeWillow Rose Gall MidgeRabdophaga rosariaGiant Goldenrod Bunch Gall MidgeGiant Goldenrod Bunch Gall MidgeRhopalomyia capitata

Sources

  • Wikipedia: https://en.wikipedia.org/wiki/Polystepha_pilulae

Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia

Text written 2026-10-22 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.

How this page works

This is one bug's fact sheet. The colored box at the top says whether it is dangerous. Sections below cover how to recognize it, whether it is a pest, and how to deal with it. The US map shows which states have records; tap a state to see other bugs there.

Every fact on Bug FAQ comes from a named source (university extension sites, government agencies, GBIF, iNaturalist, Wikipedia). The source is linked next to each section. If we have no source for something, we leave it out.