Deer Flies

Deer flies have been a nuisance in many areas this year. These flies are a little larger than a housefly and are stout-bodied. They are colored yellow or black and have dark colored markings on their wings. Their eyes are often a brightly colored green or gold pattern. Deer fly larvae live in aquatic or semi aquatic sites, like marshy areas, streams and ponds. Adults are found near these breeding grounds, especially along the edges of woodlands but they are strong fliers and can range miles away from their breeding areas.

Deer flies are most active on sunny, calm days. They have a tendency to wait in shady areas for a host. Deer flies primarily use sight to find a host and seem to be particularly attracted to moving, dark shapes. They typically go for the head and neck when biting people. Deer flies have been known to chase hosts a limited distance.

They can inflict a painful bite as they seek a blood meal. They use knife-like mouthparts to slice a wound in the skin and feed on the resulting blood. Fortunately, deer flies do not vector any disease, although some people can suffer allergic reactions to the bites. In addition to humans, these biting flies also attack many different animals, including deer, horses and cattle. Deer flies are most common in June and July, although they do persist until the end of summer.

Unfortunately, our options are very limited when it comes to preventing deer flies from biting us. It is not practical to control immature deer flies by eliminating breeding sites, i.e. marshes, streams and ponds. There are just too many potential sites to treat and the risk of environmental harm is too great. It is also prohibitive and impractical to treat adult flies in yards, parks and other areas with insecticide applications.

Control of deerflies usually comes down to personal protection. Wear protective clothing, such as hats, long-sleeved shirts and long pants to help protect exposed skin. It is more difficult for deer flies to bite through clothing. Some gardening catalogs sell sticky patches that are placed on the back of hats. The theory behind it is that the deer flies will land and stick to the patch before they can bite you. You can also try a nylon head net, similar to a beekeeper’s veil.

The use of a repellent (DEET, permethrin) may be able to provide some short-term protection. Products containing DEET may be applied to clothing and skin while permethrin products may be applied to clothing only. Be careful not to over apply these products. When using DEET products on children, use as dilute a solution as possible, usually 10 percent or less.

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