It is fairly well known that some fly species are particularly threatening to humans, while others are dismissed as a mere nuisance. Many people living in the northeast have experienced the pain of being bitten by a horse fly and/or a deer fly. It’s also common for residents and vacationers to become swarmed by cluster flies in coastal areas of the northeast. The Musca domestica species, or the “common housefly” as most people know it, can become an annoying indoor and outdoor pest during the warmer seasons in every part of the world. Houseflies, like many fly species, are attracted to a number of organic materials, most notably pathogen-rich refuse, rotting foods and feces, making the insects mechanical disease-vectors. Many homeowners have come to learn that housefly infestations can become established within a sanitary home or in a well kept yard where such foul materials are not clearly present. In these cases, large numbers of houseflies may be gravitating to decaying leaf-litter, lawn-waste, compost bins, sewage lines or nearby recycling and/or garbage bins. Housefly infestations can perplex affected homeowners due to the dramatic variance in the number of fly pests present around a home within a 24-48 hour period. For example, houseflies are always more abundant on a property during the daytime, as the insects feed during the day and rest during the night. However, there are many reasons as to why a property may seem infested with flies one day while seeming completely free of the pests another day.

Adult houseflies mate, fly, lay eggs and feed during the day, making them hard to miss in or around a home, but they do not disappear from an infested property during the night; instead, houseflies rest on ceilings and other overhead structures in large groups during the night, but houseflies can continue to remain active at night in and around homes where artificial light is abundant. This is due to the fact that houseflies have adapted to thrive in human-populated areas where they cannot discern between artificial light and the sun. Therefore, fly activity can remain bothersome at night in well-lit urban and residential areas, while infestations may seem to suddenly reappear within and around homes every morning or afternoon in areas where artificial light is relatively less abundant during the night. Houseflies are most active during the daytime hours when the temperature is between 68 and 77 degrees, and when air humidity is relatively low. It is in these conditions that houseflies mate, feed, lay eggs and fly tirelessly, but all of these activities cease when the outside temperature drops below 60 degrees. When temperatures reach 95 to 105 degrees, flies rest and remain largely inactive. When temperatures surpass 110 degrees or fall below 50 degrees, houseflies become completely dormant and undetectable to homeowners despite maintaining a high population around homes. Once temperatures fall below 95 degrees, and above 60 degrees houseflies will resume pest activity in residential and urban areas.

Have you ever had a fly infestation, but were unable to identify the source of their attraction?