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Common Horse Fly Haematopota pluvialis

Even though most flies are just 'filthy' animals, a few can be a nuisance indeed. The horse flies especially are dreaded, because they are able to bite people painfully. The females of these flies, also called gadflies or clegs, need blood in order to develop eggs, just like mosquitoes do. Mosquitoes have developed an injection needle to sting. The sting by itself is painless. However they inject certain fluids that can cause itchy bumps. These fluids prevent the blood from coagulating. Horse flies lack the injection needle. They have razor like jaws instead that cut into your flesh untill the bloods starts to run. This blood is then sucked up with a tongue that looks very much like the house fly's. You can really feel the bite. Most of these flies concentrate on bigger mammals, such as horses and cows, but the Common Horse Fly (or Cleg-fly) is fond of humans as well, especially when a thunderstorm approaches. When resting Horse Flies fold their wings over their body. When actively walking about however, they spread their wings. One female apparently found food on our car and sucked it up running about. You can see clearly now that the body has some bands at the end of each segment. Also the beautiful pattern on the wings becomes very striking. But Cleggs are best known for their wonderful eyes. Each species has another pattern of lines and colours, so you can even tell apart the various species by just looking them in the face! There are a few species though that just have plain brown eyes, without any lines or colours, so be careful when deciding the fly you're studying is not a Horse Fly. Males and females of the Common Horse Fly differ. The male has much bigger eyes than the female, but the entire upper part is plain brown. Only the lowest parts reveals two colourful lines. The male is in the bottom pictures.