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a close up of a fly

Houseflies

A house fly, known scientifically as Musca domestica, is a common insect found in homes around the world. These small, grayish-black flies, measuring about 4-8 mm, have four dark stripes on their thorax. They're equipped with large, compound eyes and transparent wings, giving them impressive flying agility.

House flies are attracted to homes mainly for food, moisture, and warmth. Here are some common reasons they end up indoors:

Food: Flies are drawn to human food, decaying matter, garbage, pet food, and even feces. They feed by releasing digestive juices onto solid food to break it down into a liquid they can consume.

Warmth: Being cold-blooded, flies thrive in warm environments. Homes, especially in cooler months, provide the warmth they need to survive and reproduce.

Breeding Sites: Flies lay their eggs in warm, moist places like garbage, compost, or rotting food. If your home has these conditions, it can attract flies looking for a place to breed.

Moisture: Flies need water to live, so homes with leaks, standing water, or damp areas can be appealing to them.

House flies are notorious for contaminating food due to their unsanitary habits. Here's a detailed explanation of how they do this:

  1. Landing on Contaminated Surfaces: House flies are often attracted to decaying organic matter, such as garbage, feces, animal waste, and rotting food. As they land on these surfaces, bacteria, viruses, and other pathogens stick to the tiny hairs on their legs and bodies. When they later land on food or food preparation areas in your home, they transfer these contaminants.

  2. Feeding Habits: House flies cannot consume solid food. To feed, they regurgitate digestive enzymes onto solid food to liquefy it. This process of "spitting" onto food introduces pathogens from their digestive system onto the surface of the food. Once the food is broken down into a liquid state, the fly consumes it using its sponge-like mouthparts.

  3. Defecation: House flies defecate frequently. As they move from place to place, including your food and food surfaces, they leave behind feces, which can contain harmful bacteria like E. coli, Salmonella, and Shigella. These bacteria can cause foodborne illnesses if ingested by humans.

  4. Transport of Microorganisms: Studies have shown that house flies can carry over 100 different types of pathogens, including bacteria, viruses, fungi, and parasites. These microorganisms can cause diseases such as diarrhea, cholera, typhoid fever, and dysentery. Flies can carry these pathogens on their body parts, such as their legs, wings, and mouthparts, as well as in their gut, which they transfer through regurgitation or defecation.

Given their feeding and breeding habits, house flies pose a significant risk of contaminating food and spreading illness. Keeping food covered, cleaning surfaces regularly, and eliminating potential breeding grounds (like garbage and organic waste) are essential steps to minimize their impact on food safety.

Similar Pests: Fruit Flies, Fungus Gnats