Many people mistakenly believe fruit flies cause small, itchy bites. True fruit flies, scientifically known as Drosophila melanogaster, do not possess the mouthparts necessary to bite humans. Their feeding structures are designed for sponging up liquids from decaying organic matter, not for piercing skin. If you are experiencing bites, another small flying insect, often mistaken for a fruit fly, is likely the culprit.
Fruit Flies: Unpacking the Myth
The common fruit fly, Drosophila melanogaster, measures 3 to 4 millimeters and has a tan or light brown body with prominent red eyes. These insects are primarily attracted to ripe, fermenting fruits, vegetables, and other sugary substances, including alcoholic beverages and vinegar. Their mouthparts are soft and spongy, allowing them to absorb liquids from these decaying materials, which prevents them from biting or piercing human skin.
Identifying the Actual Biting Pests
Several small flying insects are frequently mistaken for fruit flies but are capable of biting humans. Biting midges, often called “no-see-ums” due to their minuscule size (1-3 mm), are gray and inflict a sharp, burning bite that results in intensely itchy, red spots or welts. These bites can be more irritating than mosquito bites, causing prolonged itching. Another biting insect is the stable fly, which resembles a house fly but possesses a pointed, piercing mouthpart. Stable flies are about 5-7 mm long, gray with four dark stripes, and deliver a painful bite.
Fungus gnats, which are slender, dark-bodied flies around 1/8 inch long with long legs and antennae, are also frequently confused with fruit flies. They are commonly found around houseplants, as their larvae feed on fungi and decaying organic matter in moist soil. Although adult fungus gnats do not bite humans, their presence can be annoying and their larvae can damage plant roots. Drain flies, also known as moth flies or sewer gnats, are small (about 1/8 inch long), hairy, brownish-gray or black insects with leaf-shaped wings. While they breed in the organic sludge found in drains and pipes, adult drain flies typically do not bite humans.
Strategies to Prevent Bites
To prevent bites from these small flying insects, employ several strategies. Applying insect repellents with DEET, picaridin, or oil of lemon eucalyptus are effective against biting midges and other gnats. Botanical repellents containing citronella, lemongrass, rosemary, and geranium oils also offer protection. Wearing long sleeves and pants, especially during dawn and dusk when many biting insects are most active, provides a physical barrier against bites.
Ensuring that window and door screens are intact and have a fine mesh can help prevent smaller insects, like biting midges, from entering your home. Using air conditioning can also deter midges, as they prefer warmer, humid environments. If you are outdoors, consider using fans, as the created breeze can help keep away weak-flying insects such as gnats.
Eliminating the Biting Fly Problem
Long-term control of biting flies requires addressing their source. For fungus gnats, reduce overwatering houseplants; they thrive in moist soil. Allow the top 1-2 inches of soil to dry completely between waterings to disrupt their life cycle. Sticky traps near plants capture adult fungus gnats, and treating the soil with a diluted hydrogen peroxide solution kills larvae and eggs.
For drain flies, thorough cleaning of drains is paramount, as they breed in the organic film that accumulates in pipes. Pouring boiling water down drains repeatedly can help, or a mixture of baking soda and vinegar can break down the organic matter. Commercial drain cleaners or microbial solutions designed to break down organic buildup are also effective in eliminating breeding grounds. Maintaining overall household cleanliness, promptly disposing of trash, and ensuring no standing water sources are present can prevent various biting fly infestations.