Bug FAQSaltmarsh Greenhead Flies
Tabanus nigrovittatus · Order: Diptera · Family: Tabanidae
Also called: Greenhead Horse Fly, Salt Marsh Greenhead
Source: Wikipedia
Greenhead flies are small horse-flies about the size of a housefly and live in coastal salt-marshes of the eastern United States. Females need blood meals to lay eggs, and their bites cut the skin and suck the released blood, which can itch and hurt more than a mosquito bite.
Source: Wikipedia
Size
These flies are smaller than most horseflies, roughly the size of a common housefly.
Source: Wikipedia
Is it a pest in the house?
Biting females are a nuisance to humans and animals, staying on land searching for hosts for up to four weeks.
Source: Wikipedia
Does it bite or sting?
Their bites cut the skin with scissor-like mouthparts, causing itchy, painful wounds. A female can live three to four weeks and lay about 100 to 200 eggs per blood meal.
Source: Wikipedia
How to get rid of it
Large-scale insecticide use would harm the ecosystem, so communities use specialized black-box traps in marshes to reduce numbers.
Source: Wikipedia
Where it lives
They are found around coastal marshes and wetlands.
Source: Wikipedia
What it eats
Females bite people and animals to obtain blood protein for egg production. Larvae live in intertidal marsh mud and prey on other small invertebrates.
Source: Wikipedia
Life cycle
Eggs are laid on marsh grass; larvae develop in mud for one to two years before pupating in early spring.
Source: Wikipedia
When you see it
Adults are most common from late June through August.
Source: Wikipedia
Where it comes from
They are native to the eastern United States.
Source: Wikipedia
Where it is found in the US
Recorded in 19 of 51 states and DC. Most records: Massachusetts, Louisiana, South Carolina, Mississippi, Florida, Maine, Virginia, New York.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: native in North America; native in Canada. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
Do greenhead flies bite?
Yes, the females bite people and animals, cutting the skin and sucking blood, which can itch and hurt more than a mosquito bite.
Source: Wikipedia
When are greenhead flies most active?
Adults are most common from late June through August after emerging in late spring.
Source: Wikipedia
How can I reduce greenhead flies around my home?
Communities often install black-box traps in nearby marshes, as broad insecticide use would damage the ecosystem.
Source: Wikipedia
Same family (Tabanidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Tabanus_nigrovittatus
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-24 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-24.