Along with several species of home-invading cockroaches, ants and termites, flies are one of the most common groups of insect pests found within and around homes and buildings. Hearing the term “fly pests” conjures up images of the frequently encountered and annoying domestic house fly species (Musca domestica), but several fly species that closely resemble house flies invade homes throughout the United States regularly, including blow flies, fruit flies, drain flies, cluster flies and face flies. These fly pests are commonly known as “filth flies” due to their habit of breeding on all different sorts of decaying and pathogen-rich organic matter, such as garbage, dead vegetation, rotten food, excrement, and animal carcasses. Due to the abundance of readily available sources of organic matter found within nearly all types of indoor and outdoor environments, numerous filth fly pest species have successfully established non-native habitats that span much of the world.
Flies belong to the Diptera order of insects, which is comprised of more than 125,000 species worldwide, but experts estimate that an additional 1 million fly species of this order have yet to be discovered and properly documented. While a great many Diptera fly species resemble the house fly, this order also includes many other well known groups of winged insect pests, including mosquitoes, gnats and crane flies. One of the most significant indoor filth fly pest species found throughout the US, the “face fly,” favors livestock manure as a breeding site, making them common in rural homes that are located near expansive agricultural landscapes. However, face flies often enter urban and suburban homes in massive numbers during the fall and winter seasons in order to secure a warm overwintering site.
Face flies first appeared in the United States during the 1950s when large congregations began invading eastern and midwestern homes during the colder months. Eventually, these fly pests expanded their habitat all the way to the Pacific Coast and southward into Arizona, and today, face flies are common indoor pests of homes throughout the state. Face flies appear identical to house flies, but face flies are often recognized as a separate species when they indulge in their seemingly unusual infestation behaviors during the fall and winter. After swarming indoors, face flies establish harborages in hidden and often inaccessible indoor areas, particularly wall voids and tight attics spaces, but unlike cluster flies, which also invade homes in order to overwinter, face flies almost always die within their hiding spots before the arrival of the spring season. As a result, face fly infestations see countless dead specimens collect within wall voids where they attract other insect pests that prefer to feed on flies, most notably carpet beetles.
Have you ever experienced an insect infestation that started in response to an already existing infestation?