Latin: Tabanus Sudeticus
The horsefly is a numerous but small animal species in Denmark. We have found 37 different species, where the dark giant horsefly is the largest. However, the horse claw (tabanus sudeticus) grows on average 2.5 cm long, so they are generally a very petite insect. However, they can be a major annoyance to many as they are bloodsuckers.
Horseflies are also called botflies, but this is technically incorrect. Botflies belong to a different family than horseflies, and horseflies are bloodsuckers, which botflies are not. Horseflies do not move much once they have settled down, which has led to this idea that it is blind flies. However, horseflies have highly developed eyes, and they therefore see well. They especially use their sharp eyesight to find prey.
Appearance
A horsefly is a type of fly. It has large eyes and either clear or spotted wings, but how it may otherwise look depends on the specific species in question. As mentioned, there are three species of horseflies in Denmark, and they are similar in shape.
Haematopota pluvialis has soot-colored wings and is smaller. Haematopota pluvialis are especially often seen on humid summer days. However, another type of horsefly, the Chrysops relictus has brown and spotted wings as well as yellow markings on the hind body.
Biology and behavior
There is a big difference in how the individual species of horseflies can look. Likewise, they can also behave very differently, as some of the species make a lot of noise when flying, while others are completely silent. It can therefore be difficult for an ordinary person who does not know much about insects to find out if it is a horsefly or a regular fly that has just landed on them.
When adult horseflies reproduce, they stick their eggs to various moist surfaces, such as plants, blades of grass and particularly moist stones. From the eggs hatch such small larvae. The hatching larvae crawl into swampy soil, which is typically found in Denmark by masses of water such as puddles, lakes, and the like. The larvae are predators that eat other insect larvae as well as other small animals such as worms.
Damage
A bite from a horsefly is less elegant than a bite from a mosquito, as the horsefly simply cuts a hole in the skin so they can suck the blood. However, this type of bite can be extremely painful, and it can also lead to severe swelling on some people. So, you can recognize a bite from a horsefly that it hurts extremely. The hole left by the horsefly will be triangular and you may risk severe local swelling.
Horsefly can also bite cattle and horses. In some places abroad, this can be particularly dangerous as the flies transmit diseases and parasites to the animals. In Denmark, however, we have not seen many signs of this danger with transmission, but bites from horseflies will of course not be pleasant for one’s cattle or horses.
Prevention and pest control
Unfortunately, horseflies are difficult to control and prevent, as their larvae are particularly tough, and adult flies are also difficult to control. It is not possible in Denmark to find specific chemical agents for horseflies, such as for mosquitoes and other insects, but there are lotions that can soothe the pain.
Lotion with lidocaine helps with both pain and swelling after a bite, and this can typically be bought at the pharmacy. Local anesthetic gels can also help. After one bite from a horsefly, you typically do not want to try that again, but you can take some precautions. The easiest way to avoid bites from horseflies is simply to stay away from their preferred environment, i.e., swampy nature. If you live in an area with many horseflies, or if you know that you traveling to an area with many horseflies, regular mosquito spray can help. Horseflies rarely fly inside, and when they do, they are typically too busy getting outside again to bite.
"Pests in House and Home"
"Bed Bugs - Bites, Stings and Itches"
"Food Pests"
"Husets dyreliv" (Insects Around the House - Only danish)
"Skadedyr i træ" (Timber Pests - Only danish)
"Stuefluen" (Common Housefly - Only danish)