Flies are a common nuisance, often seen buzzing around our food and homes. A common concern is whether they can eat through plastic containers to access stored food. The straightforward answer is no; flies cannot eat through plastic. This article explores the biological reasons for this inability, discusses how flies interact with plastic surfaces, and offers guidance on protecting your food and living spaces.
Understanding Fly Mouthparts
Flies possess highly specialized mouthparts designed for consuming liquid or semi-liquid food, not for chewing through solid materials like plastic. Common house flies (Musca domestica) have sponging mouthparts. These consist of a fleshy, retractable proboscis with two spongy lobes (labella) covered in fine grooves (pseudotracheae) that soak up liquids. When a house fly encounters solid food, it secretes saliva onto the surface to dissolve it, turning the solid into a liquid that can then be drawn up by capillary action into its food canal.
Other types of flies, like the stable fly (Stomoxys calcitrans), possess piercing-sucking mouthparts. These elongated, rigid mouthparts form a bayonet-like structure for piercing skin to feed on blood or other fluids. Unlike insects such as grasshoppers or beetles, which have strong mandibles for biting and chewing solid food, flies lack these robust chewing structures. Their mouthparts are adapted solely for processing liquids, making them physically incapable of breaking down or consuming solid plastic.
The Impossibility of Eating Plastic
The physical properties of plastic, combined with the specialized nature of fly mouthparts, render it impossible for flies to eat through this material. Plastic is a hard, durable substance with a complex molecular structure that offers no nutritional value to flies. Their sponging or piercing mouthparts are not equipped to chew, bore, or dissolve solid plastic.
Even if a fly were to land on a plastic surface, its mouthparts could not inflict any damage. While some insect larvae, like certain moth larvae, might be able to chew through thin plastic, adult flies lack this capability. The idea of a fly “eating through” plastic is a misconception, stemming from concerns about contamination rather than actual consumption.
Flies and Plastic: Other Interactions
While flies cannot eat through plastic, they interact with it in ways that can affect food safety and hygiene. Flies frequently land on plastic surfaces, like food containers or countertops, acting as mechanical vectors for bacteria and other pathogens. Their bodies, especially their legs and mouthparts, can pick up microorganisms from decaying matter, feces, or other contaminated sources. These contaminants are then transferred to new surfaces upon landing, including plastic.
Flies may also lay eggs on plastic surfaces if an accessible food source is present. For example, if a plastic bag contains decaying organic matter or food residues, female flies might deposit eggs on or near it, attracted to these materials for egg-laying. However, they do not lay eggs through the plastic itself, nor can their larvae (maggots) consume plastic. Flies are also attracted to plastic containers with exterior food spills or residues, as these provide a readily available food source.
Protecting Your Food and Home
While flies cannot penetrate plastic, their ability to contaminate surfaces makes preventative measures important. To protect food and maintain a hygienic home, focus on practices that deter flies from accessing food items and breeding sites. Storing food in sealed, fly-proof containers, whether plastic, glass, or other materials, is an effective way to prevent access.
Prompt cleanup of food spills and crumbs is essential, as these attract flies and provide potential breeding grounds. Proper waste management, including using garbage cans with tight-fitting lids and regular emptying, helps eliminate attractive sites for flies. Maintaining clean kitchen surfaces and ensuring windows and doors have intact screens reduces the likelihood of flies entering and contaminating your living space.