15/05/2026
Recently we had a question from a concerned horse owner about march flies and what she could do to prevent them from biting. Below is a bit of information about march flies and what you can do, to stop them annoying your horse.
What march flies actually are:
March flies (also called tabanids) belong to the same family as horseflies. This means:
• They’re strong fliers
• They’re aggressive biters
• Their mouthparts are designed to cut the skin, not pierce it
• Their bites can cause pain, swelling, and agitation
They’re not like regular houseflies — they’re much tougher and far more determined.
Why march flies bite horses:
Female march flies need blood meals to produce eggs. They’re attracted to:
• Heat (warm bodies)
• Movement (horses swishing, walking, trotting)
• Dark colours (black, navy, dark bay coats)
• CO₂ (breathing)
• Shiny coats (sunlight reflection)
This is why even well groomed horses get hammered by them.
When march flies are most active:
March flies thrive in:
• Hot, humid weather
• Still air (low wind)
• Midday to late afternoon
• Near water, bushland, and paddocks with shade
If your horse is stomping more in the afternoon, this is why.
Why they’re so hard to repel
Unlike mosquitoes or stable flies, march flies don’t rely heavily on scent to find their target. They use:
• Vision
• Heat detection
• Movement tracking
This is why even strong smelling repellents only offer partial protection — but partial protection still makes a big difference in comfort.
What actually helps reduce march fly landings:
Horse owners can manage march flies by combining a few strategies:
1. Strong essential oil sprays
Oils like citronella, eucalyptus, geranium, peppermint, cedarwood, neem, and lavender help mask scent cues and reduce landings.
2. Non water based formulas
These stay on longer in heat, sweat, and humidity — crucial during march fly season.
3. Light coloured rugs
March flies prefer dark surfaces. A light rug can reduce attraction significantly.
4. Shade + breeze
They struggle to fly in wind and avoid cooler, shaded areas.
5. Avoiding peak times
Hot, still afternoons are the worst.
For my own horses, I’ve been using EquiShield Protect because it’s non water based and uses those stronger essential oils that help deter biting insects, including march flies. It doesn’t stop them completely, nothing does, but it definitely reduces landings and keeps my horses more settled.