Flying – Biting
Horseflies are up to 1 inch in length.
They are mostly dark brown, grey or black, with dark eyes, often with a metallic sheen.
Horseflies are often large and agile in flight and the females bite animals, including humans, to obtain blood. They prefer to fly in sunlight, avoiding dark and shady areas and are inactive at night. Female horseflies can transfer blood-borne diseases from one animal to another through their feeding habit. They can reduce growth rates in cattle and lower the milk output of cows if suitable shelters are not provided. Horseflies can lay claim to being the fastest flying insects, with a recorded reaching speeds of up to 145 km per hour (90 mi/h) when pursuing a female.
Horseflies mostly occur in temperate, subtropical and tropical areas with suitable moist locations for breeding, but also occupy a wide range of habitats from deserts to alpine meadows. They are found most in rural farmland area, from sea level to at least 3,300 m.
Tips for Control
Controlling horse-flies is difficult. Insect repellents rarely deter them.
Fly traps are most often used to capture horseflies and these can be modified with the use of baits and attractants that include carbon dioxide or octenol. Humans find horsefly bites painful. Usually, a weal (raised area of skin) occurs around the site and other symptoms may include urticaria (a rash), dizziness, weakness, wheezing and angioedema (a temporary itchy, pink or red swelling occurring around the eyes or lips). A few people experience an allergic reaction. The site of the bite should be washed and a cold compress applied. Scratching the wound should be avoided and an antihistamine preparation can be applied. In most cases, the symptoms subside within a few hours, but if the wound becomes infected, medical advice should be sought. If a property owner needs to control horseflies, it is best to contact a pest professional for advice on methods that are effective and to find out what can legally and practically be done for control.