Insect identifier · Biting flies
How to identify a Horn fly
Haematobia irritans
· Also called hornfly, cattle fly, cattle fly bite, flies on cows that bite
Small dark flies that stay on cattle’s backs. People get bitten walking through herds. Not the ankle-biting stable fly.
If the bites only happen when you walk through cattle, look at the cows’ shoulders. Horn flies live there in a dark carpet. They will bite people in the pasture and then go back to the animal. Patio ankle bites away from livestock are stable flies. Control is veterinary and pasture management, not a bedroom spray.
What does a horn fly look like?
Smaller than a house fly, clustered on cattle shoulders and backs.
Horn fly (Haematobia irritans) is Smaller than a house fly, about 4 mm. Colors people notice: black, gray. Field marks: Stay on cattle, clustered on the back and shoulders; Small dark flies; People get bitten when walking through herds. It is found outdoor. If those marks are missing, open Stable fly before you force this name. Search phrases that belong on this page include what a horn fly looks like and horn fly identification.
Identification marks
- Stay on cattle, clustered on the back and shoulders
- Small dark flies
- People get bitten when walking through herds
Size: Smaller than a house fly, about 4 mm
Colors: black, gray
Where: outdoor
What a typical horn fly bite looks like
Sharp bites on arms and neck after time around cattle. Small itchy welts. Primarily a livestock pest.
People searching “horn fly bite identification” want the pattern, not a single anonymous bump. Sharp bites on arms and neck after time around cattle. Small itchy welts. Immediate steps on this page: Leave the herd area; Wash and soothe; Ranch workers: talk to extension about herd fly control. This species does bite or sting people. Fever, spreading redness, trouble breathing, or a child with many stings is professional care.
If you were bitten
- Leave the herd area
- Wash and soothe
- Ranch workers: talk to extension about herd fly control
Horn fly vs Stable fly
They live on the cow. Stable flies hit people on ankles even away from the herd. If you only get bitten walking through cattle, horn fly is likely.
- Stable fly identification (Stomoxys calcitrans)
- House fly identification (Musca domestica)
Range and season
Wherever cattle are raised, warm months.
Cattle country across North America in warm months.
Wherever cattle are raised in North America.
Warm months
Common questions
Do horn flies bite people?
Yes, but they strongly prefer cattle.
Horn fly vs stable fly?
Horn flies stay on the animal’s back. Stable flies bite ankles and look more like house flies.
Are they a disease risk to people?
Primarily a livestock pest.
What fly stays on cows and bites people?
Horn flies. They cluster on the animal’s back and will bite people in the pasture.