Filth flies are a group of fly pests that congregate on decaying organic materials and animal waste products that contain countless disease-causing microorganisms. Fruit flies and house flies are two well known insect pests that are categorized as filth flies due to their instinctive habit of congregating on animal excrement, rotting food, animal carcasses, compost, rotting plant matter, overused mop heads, garbage and dirty rags. Filth flies seek out these microbe-rich environments for feeding, mating and egg laying purposes. This is why it is not uncommon to encounter fly larvae (maggots) within the filthiest locations that exist in urban areas.

Although they cannot be readily seen, filth flies possess tiny hairs on their body, as well as sticky and hairy feet that allow the insects to adhere to walls and ceilings. When filth flies crawl around on decaying organic matter and animal waste products, their bodily hairs and sticky feet snag chunks of foul matter that are made up of numerous disease-causing pathogens. Since many filth flies have adapted to dwelling in urban and residential environments, they frequently travel between homes and their foul breeding grounds, allowing filth flies to spread disease-causing pathogens everywhere they may crawl within a home, including dining room tables, countertops, fruit kept with bowls, cooked foods, stored foods, clean dishes and eating utensils. House flies alone can carry more than 65 microorganisms that cause a variety of diseases, including typhoid fever, dysentery, cholera, poliomyelitis, yaws, anthrax, tularemia, leprosy and tuberculosis.

Unlike some filth fly pests, like stable flies, horse flies and deer flies, house flies do not bite humans, and they cannot bite into solid foods; instead, house flies dissolve solid foods with their corrosive vomit before using their sponge-like mouthparts to suck up the soupy remains. This horrible process occurs every time a fly is spotted landing on a human food source. Of course, the disease-causing pathogens collected from filthy breeding sites also contaminate the food sources that house flies land on. Researchers are now rethinking the health threat that common filth flies pose to the public, as a recent study found that house flies are twice as filthy as cockroaches.

Have you ever eaten a piece of food that a fly landed on?