What Are Horseflies?

horse flies uk
This horsefly seen in North Somerset was huge!

Horseflies are among the most disliked insects because their silent flight often ends with us receiving a painful bite.

Horseflies fly during the day, so at night you are safe from these insects unless one flew into your home and is using your artificial light to home in on you!

Horseflies vary in size from that of a housefly to something resembling the size of a bumblebee. Silent flight means that even the most substantial flies at over 1inch, seem to float down onto you! Another feature of these flies is their amazing sometimes dazzlingly colourful eyes.

Controlling horse flies is almost impossible, but we describe some barrier options further down the page.

Horseflies In The UK & Beyond

Horseflies in the UK comprise of just 30 different species, in two families. We can loosely define these as the family Tabanidae (non-patterned wings) and the family Chrysopsinae (patterned wings).

Globally there are at least 4400 described species found almost everywhere, but predominantly in warmer environments. UK species of horsefly are found mostly in the south.

The female’s eyes are separated by a vertical band or eye-bridge, while the eyes of the male are close together, making identification easier.

horseflies eyes male
The males eyes appear almost fused together

How Dangerous Are Horseflies?

Horsefly bites are highly infectious – but not transmittable. What this means is that horse fly saliva contains many different bacteria and antigens that regularly cause some significant physiological side effects in the hosts skin.

In the UK, Horsefly bites readily become infected, and elsewhere in the world, these flies carry many disease-causing agents and parasites. There is even a case of a bite causing anaphylactic shock!

horse fly bites
Horse Fly Bites

These skin lesions commonly produce scars that will last a lifetime and we know this because we see people including ourselves with bites like this Every Single Year!

Other insects that cause bites on humans in the home or outdoors include bedbugs and fleas.

Prevent Horse Fly Bites

Horse Fly Bites are only a risk where they are actively feeding on you as the bacteria in the saliva infects bite sites causing swelling and infection.

Adult horse flies don’t always feed on blood. The blood-feeding behaviour is pertinent only to the female.

Males don’t bite, but both males and females will feed on nectar and plant exudates, providing the service of pollination.

The female horse flies use specialised mouthparts or blades to saw into the skin and sponge up the blood meal. Females feed on blood only to acquire the protein necessary to develop eggs after mating.

Repellents and barriers have their place, but can almost never completely remove the chance that bites will not occur.

Barriers available for horses and associated livestock include masks, blankets and sheets. There are even specialist devices designed to mimic the flies prey, that are effective to a point. Carbon dioxide has also been used but to little effect.

Repellents are available, but nature is not equal and there is always going to be exceptions to the rule.

What this means is that horseflies are not always attracted to a specific ingredient. All products of this nature can be effective, but no single formula is effective on all horse fly species.

Learn more about horseflies. – UK Horseflies