Bug FAQYellow-footed March fly
Bibio xanthopus · Order: Diptera · Family: Bibionidae
Bibio xanthopus is a common North American March fly with a black body, pale pile and mostly rufous legs; females have black wings. Adults are 8 to 11 mm long with wingspans of 5.5 to 9.5 mm, and the larvae are about 10 mm long, warty, and feed on plant roots.
Source: Wikipedia
How to recognize it
Females have black wings.
Source: Wikipedia
What it eats
The maggots feed on plant roots.
Source: Wikipedia
Where it is found in the US
Recorded in 20 of 51 states and DC. Most records: California, Washington, Maine, Minnesota, Oregon, Connecticut, Montana, Alaska.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
How big are adult Bibio xanthopus?
Adults measure 8 to 11 mm in body length with wingspans of 5.5 to 9.5 mm.
Source: Wikipedia
Same family (Bibionidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Bibio_xanthopus
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-27 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-27.