Flies, common insects found globally, are often seen landing on various surfaces, including food. A frequent question arises regarding their waste elimination processes, specifically whether they excrete. Flies do eliminate waste. Understanding fly waste involves distinguishing between their solid excrement and regurgitated material, both of which are deposited onto surfaces.
The Mechanics of Fly Excretion
Flies possess a digestive system that processes consumed food, similar to other animals. They absorb necessary nutrients, and then eliminate any undigested material as waste. Fly excrement appears as small, dark spots, commonly referred to as “fly specks” or “fly dirt.” These spots are typically black or dark brown dots, sometimes with lighter amber or cream-colored areas.
The color and consistency of these specks can vary based on the fly’s diet. Due to their liquid diet, flies digest food rapidly and defecate frequently, often doing so wherever they land. This regular defecation contributes to the accumulation of these small, dark spots on surfaces where flies frequently rest, such as windowsills, near sink drains, and around waste receptacles.
Distinguishing Excrement from Regurgitation
A common source of confusion is differentiating between fly excrement and regurgitation. Flies cannot chew solid food, so they typically consume liquids. To process solid food, they regurgitate digestive enzymes onto the food source to liquefy it, then consume the resulting liquid. This process leaves behind a “vomit spot.”
Regurgitation spots are lighter in color and more translucent than excrement. They appear as wet spots that dry, in contrast to the darker, more opaque, and solid nature of fecal spots. While excrement is the result of digestion and elimination, regurgitation is a pre-digestion process, leaving distinct types of deposits.
Why Fly Waste Matters
Fly waste holds practical significance due to its role in transmitting pathogens. Flies frequently land on unsanitary surfaces like garbage, decaying matter, and fecal matter, picking up bacteria and viruses. Through their excrement and regurgitation, along with particles on their bodies and legs, they can transfer these microorganisms to human food, utensils, and other surfaces.
This mechanical transmission of pathogens poses health risks, including food contamination and the spread of various diseases. House flies, for instance, are known to transmit numerous diseases, including food poisoning, dysentery, cholera, E. coli, and Salmonella. The longer flies remain on a surface, the greater the chance of pathogen transfer and multiplication.