Insects like dragonflies, wasps, bees, butterflies and moths possess one set of forewings and one set of hindwings, giving them four wings in total. Insects like mosquitoes, house flies, and fungus gnats possess only one set of wings, which makes them a part of the Diptera order of insects. More than 125,000 Dipteran insect species have been documented, and this order is home to the many fly pest species that live in close association with humans. A recent study that saw researchers analyze Google search data in all 50 states found that flies dominate pest control internet search queries in Maine by a large margin over mosquitoes, cockroaches and bed bugs. According to a 2016 nationwide survey of pest management professionals, domestic house flies, fruit flies, drain flies, phorid flies, and blow flies are the most commonly controlled fly pests of homes. These fly species are commonly known as “filth flies” due to their natural habit of breeding on sources of decaying organic matter, such as excrement, garbage, rotting food, compost, and dead animals.

Adult female filth flies lay their eggs on microbe-rich sources of organic matter so that their larval offspring (maggots) will have plenty to eat after hatching. The maggot offspring of all filth fly species feed on the soluble matter in organic waste, as well as the microscopic microflora and fauna that thrive on organic waste, as doing so provides maggots with the nutrients they need to develop into adults. The sources of organic waste where filth fly females prefer to lay their eggs differ somewhat from species-to-species. However, the domestic house fly female is free to lay her eggs on just about any form of organic waste, including human and animal excrement, rotting food in wastebaskets, rotting food beneath appliances, dead plant matter, animal carcasses, sewage and even tiny bits of food on counters. This is why house flies can be found in any human setting, and it’s also why house flies are covered in millions of disease-causing microorganisms, some of which cause human diseases like dysentery, diarrhoea, typhoid, and cholera. In fact, a recent study conducted at Penn State found that house flies are even more filthy than previously thought. The researchers learned that house flies can transmit Helicobacter pylori and 15 other pathogens that were not previously known to be carried and transmitted by house flies. H. pylori leads to dangerous stomach ulcers, and the World Health Organization states that house flies can spread Salmonella enteritidis, virulent E. coli, and even leprosy. Because of this recent discovery, many experts claim that house flies are an even greater threat to public health than cockroach pests.

Have you ever discovered a hidden fly breeding site within your home?