Are Horse Flies Dangerous To Humans? Horseflies are insects that belong to the order known as Tabanidae, and the genus referred to as Tabanus. These flies are also referred to by many other names including gad fly, greenheaded monster, breeze fly, and ear fly. These flies exist in most regions around the world, excepting arctic regions. Although horseflies are most common in the United Kingdom, they are certainly abundant within America as well, especially Florida. You have probably encountered a horsefly at some point during your lifetime. It is not uncommon to dismiss horse flies as being large house flies. This is because their overall appearance is seemingly identical to house flies, only much larger. Horseflies can be as small as normal sized house flies, but they are often noticeably bigger, sometimes as large as bumblebees. Horseflies can sometimes appear to possessing metallic eyes, but there are several species of horsefly that may look a bit different. For example, the horseflies referred to as Tabanus lineola have bright green eyes. The lineola is also among the most abundant of horsefly species. What is most important to know about horseflies is that they often carry diseases such as tularemia, trypanosomiasis and even anthrax. Only female horseflies pose a threat to humans and animals, as they are aggressive blood suckers. In fact, female adult horseflies have been known to collect up to three ounces of blood per day from their hosts. Adult horseflies are fast and strong fliers. They are most often found dwelling around marshes, wooded areas and streams. These are areas where children may explore or adults might hunt. Being mindful of horseflies is important. Horseflies also pester, you guessed it, horses. Covering a horse with a blanket may help prevent disease transmission via horsefly. If horseflies become too abundant in a particular farming region, farmers may even have to adapt to their presence by doing their farming during the night when horseflies are not active. Have you ever spotted a horsefly? If you have, did you realize that females could carry deadly diseases at the time?