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Do horse flies bite people in New Zealand?

Yes. The females cut the skin to drink blood and the bite is genuinely painful. They are most common around farmland, wetlands, lakes and beaches on warm summer days.

How do I stop horse flies biting me?

Wear light-coloured, loose clothing, use a repellent on exposed skin, and avoid wetland and paddock edges on warm still days. Horse flies are drawn to dark moving shapes, warmth and carbon dioxide, so keep moving and cover up.

What does a horse fly bite look and feel like?

Painful from the moment it happens, because the female cuts the skin rather than piercing it. The bite often swells and itches for several days and can bleed. Scratching risks infection, so keep it clean.

Are horse flies dangerous to horses and livestock in NZ?

They are a painful nuisance and large numbers can distress stock. In New Zealand they are not a major disease vector for livestock the way they are in some other countries, but they can still worry animals and draw blood.

Will a GotchaPest fly trap catch horse flies?

Not reliably. Horse flies are drawn to movement, heat and carbon dioxide rather than the sweet or protein baits our reusable traps use, so avoidance and protective clothing are the practical control. Our fly traps are excellent for the house flies and blowflies around your home and bin.

Why are horse flies worse on warm, still days?

They are strong, fast fliers that struggle in wind, so they hunt on warm, still, sunny days. Breezy days and shaded, breezy spots give you a natural break from them.

Horse Fly

The big, biting fly that draws blood in a New Zealand summer.

NZ Pest Guide

Horse flies are the large, stout-bodied flies whose females cut the skin to drink blood. In a New Zealand summer they are a persistent and painful biter around farmland, wetlands, lakes and beaches, and a single fly can chase you for hundreds of metres.

Only the females bite — they need blood to develop their eggs — while the males live on nectar and harm no one. Horse flies are strong, fast fliers and their bite is genuinely painful, so understanding when and where they are active is the key to avoiding them.

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How to identify a horse fly

A horse fly is a big, robust fly, often 10–25 mm, with a stout dark or mottled body, large often green- or purple-striped eyes, and broad wings. In flight it sounds heavier and buzzier than a house fly. The females have a wide space between the eyes; in males the eyes meet at the top.

•Large robust fly, 10–25 mm, dark or mottled grey-brown.
•Big, often brightly striped eyes — green, purple or copper.
•Stout body and broad wings; a heavy, buzzing flight.
•Females have a gap between the eyes; males eyes meet at the top.

How dangerous is a horse fly?

The bite is painful and draws blood because the female cuts the skin with blade-like mouthparts rather than piercing like a mosquito. The bite can swell and itch for days, and a small number of people react strongly. Scratching can lead to secondary infection. Around livestock, large numbers can distress animals and, overseas, horse flies spread disease — in New Zealand they are mainly a painful nuisance rather than a major disease vector.

Life cycle & fun facts

Females lay batches of eggs on plants overhanging water or wet mud. The larvae drop into the mud or water and develop there, often taking a year or two to mature before pupating. Adults are most active on warm, still, sunny days.

Fun fact: A female horse fly needs a blood meal before she can lay eggs — without it her eggs will not develop. Males, by contrast, never bite and live only on nectar.

What horse flies eat

Males feed only on nectar. Females drink nectar for energy but need a blood meal to develop their eggs, which they get by cutting the skin of mammals — including people, horses and cattle — and lapping the blood that pools.

How to avoid horse fly bites

Horse flies are drawn to movement, dark colours, warmth and carbon dioxide — so avoidance and protective clothing do more than any bait trap.

Remove the attraction

✓Avoid wetland, lake and paddock edges on warm, still, sunny days when horse flies are most active.
✓Wear light-coloured, loose clothing — horse flies favour dark moving shapes.
✓Use a repellent on exposed skin during peak hours.
✓Keep moving; horse flies are attracted to still, warm bodies.

Block them out

✓Fit fine screens on windows and doors of rural homes near wetland.
✓Our reusable fly trap catches house flies and blowflies around the home, but horse flies are best managed by avoidance — see our fly traps page.
✓Wear long sleeves and trousers in paddocks and around horses in summer.
✓For livestock, talk to your vet about targeted horse-fly control.