Summary: Horse flies are pests that pose a threat to humans and animals because they transmit diseases. The Horse fly serves almost no benefit to humans.
There are numerous types of horse flies including the Striped horse fly, the Greenhead, the Black horse fly, the Western Black horse fly and many others. For the sake of those of you having come to this website for immediate relief, I'm going to get right down to business. You probably want to know what just bit you, do you need to do anything about it and how can you avoid being bitten by that “thing” again.
A typical horse fly is as big, if not bigger, than the average house fly. It can grow up to one and one-quarter inches in length. That is a major-sized fly. Not quite big enough to carry off your dog, but certainly large enough to get your full attention. The horse fly's most distinguishing physical characteristic is its three sets of antennae. They also have two sharp jaws used for biting, which you know firsthand.
Adult horse flies are very active in wet or marshy areas and they are attracted to warm, sunny climates and big moving objects like horses, of course. Female horse flies eat mammals' blood, while male horse flies eat sweet nectar, plant sap, and pollen. So, now you know it's the female that is trying to take a chunk out of your leg. The horse fly sticks its head into its prey and sucks out juice or blood using six different mouth parts to pierce the hide or skin of its prey with a razor-sharp bite. It's a moment you won't soon forget.
Female horse flies are pests because they bite humans and animals, often causing allergic reactions, such as wheezing, rashes, and hives. Because horse flies may feed on several different species of animals, they can carry diseases and pass them on as they bite new prey.
Fortunately, horse flies do not appear in most of the United States until the summer. However, they can be seen year-round in Florida. If you have a swimming pool in your backyard you should be on the lookout for horse flies. The bad news is that there are no simple solutions to keeping them away from your pool. To avoid them, it is best to go inside until they fly away. If you notice that there are several horse flies around your yard in the summertime, staying indoors during the day is the easiest approach to avoid them. (You will also avoid sunburn, too!) At night, horse flies do not pose a threat because they are not active after sundown. They are also less active on windy days.
It is extremely hard to control horse flies because their breeding grounds can be far away and bordering ponds, lakes and streams where pesticide use is difficult. If you have a small creek in your backyard that does not contain fish, you could consider draining it in order to take away horse fly breeding areas. You could wear a nylon head net or a mesh jacket all the time, but those netted safari hats look really stupid when you're grocery shopping, don't they? If you are gardening or mowing the lawn, wearing a hat, a long-sleeved shirt and pants (especially in light colors) will deter horse flies.
You can also use any insecticide spray labeled for use around plants and vegetables, of course, to spray bushes or shrubs near wet areas to help dissuade them. However, do not ever want to spray insecticide in ponds or creeks because it will kill fish in the blink of an eye.
If you notice horse flies around your yard, make sure to bring your dog, cat, or pet llama indoors until they fly away. The horse flies. Not the dog, cat or llama. Animals are susceptible to diseases carried from horse flies and the horse fly bites really hurt them, as well.
Here is the most creative solution to pesky horse flies. You can create a contraption to ensnare them. Take a table or stool and attach a dark colored medium sized ball to a rope that hangs underneath. Apply sheets of flypaper underneath the flat surface and around the rope. Horse flies will be attracted to the dark ball, especially if it is swinging. When they realize the ball provides no source of food for them, they will fly upwards and either get caught in the flypaper or the net. Or, you can buy the Horse Pal fly trap on line for about $230, plus shipping. It ain't magic, but it's better than nothing.
Click here to watch my short video on how to control flies.