Multiple fly species found in Louisiana are commonly referred to as “yellow flies,” but experts claim the species D. ferrugatus is the only true yellow fly species in the country. Like many fly pests, the yellow fly bites humans, but yellow flies are one of the few biting fly species that attack humans within homes. Yellow flies are abundant household pests in the southeast US, and they are among the only flies in their genus with a habitat range that extends into the US from the tropics.

Only female yellow flies inflict bites to humans, and these pests are considered the most frequent biters among fly species in all US areas where they are found. Unlike many other biting flies that prefer the blood of other animals over humans, yellow flies aggressively collect human blood meals indoors. The bites are reported as being quite painful, and they often leave behind itchy welts that have been known to lead to secondary infection in rare cases.

Yellow flies are most likely to invade homes in the late afternoon and on cloudy days when they are most active. Homes that are located near bodies of water or wooded areas are particularly vulnerable to yellow fly invasions, as the species favors these habitats. Once indoors, yellow flies will bite any area of exposed skin in order to collect blood meals, and due to their nearly inaudible flying sounds, humans often become aware of an indoor yellow fly presence only after feeling the sharp pain of a bite. These flies will also readily attack dogs and they are most abundant from April to June, but homes can be invaded as late as November.

Unfortunately, there does not exist any effective pest control method to keep populations of yellow fly larvae in check. Mosquito repellents containing DEET are somewhat effective at repelling yellow flies when they are prevalent and hungry for blood. The only truly effective method of preventing yellow fly bites are headnets, and those with known allergies to insect saliva should take every measure to avoid yellow flies, as they are well documented as inducing serious allergic reactions in response to their bites.

Have you ever sustained a bite from a yellow fly? If you have, did the bite occur indoors?