Gnats are not a single species but a catch-all term for several small, non-biting flying pests that thrive in human environments. Understanding why they are drawn to you is the first step toward effective control, which relies on accurate identification and targeted environmental management.
Identifying the Pest
The three most frequent indoor culprits are the fungus gnat, the fruit fly, and the drain fly. Each has a distinct appearance and preferred breeding site that guides the necessary elimination strategy.
Fungus gnats are slender, dark-colored flies that often resemble miniature mosquitoes with long, spindly legs. They are weak, erratic flyers that usually stay close to the ground, frequently seen near houseplants. In contrast, fruit flies have a stout, compact body, are tan or brown, and often feature bright red eyes. These agile fliers hover near ripe produce, garbage, or fermentation sources.
The third possibility is the drain fly, sometimes called a moth fly, which has a fuzzy, moth-like appearance with large wings. These insects primarily breed in the gelatinous biofilm that coats the inside of plumbing and sewer pipes. Observing where the insects congregate—plants, kitchen counters, or bathroom drains—provides the strongest clue for identification.
Why Gnats Are Drawn to the Human Body
Gnats fly directly toward a person’s face because they detect metabolic byproducts. Humans constantly exhale a plume of warm, moist air rich in carbon dioxide (CO2), which small insects use as a long-range beacon. This CO2 signals the presence of a large mammal, often associated with the moisture and organic matter they seek.
Beyond the breath, the human body is a source of heat and moisture that mimics their ideal breeding conditions. Sweat, in particular, attracts gnats because it contains salt and various chemical compounds, such as lactic acid. These substances provide a nutritional draw or indicate a source of hydration.
This attraction is why the insects seem to target areas around the eyes, nose, and mouth. The combination of exhaled CO2, moisture from breath and tears, and the salt in sweat makes the head and face a highly concentrated target. Certain sweet or fruity scents from shampoos, lotions, or perfumes can also act as an additional lure, intensifying the annoyance.
Eliminating Common Breeding Sources
Long-term relief requires eliminating the source where larvae develop, which is typically a place of persistent moisture and organic decay. For fungus gnats, the focus must be on houseplants, as their larvae feed on soil fungi and decaying plant matter in overly wet potting mix. Allowing the top two inches of soil in potted plants to dry completely between waterings is often enough to break the breeding cycle.
If the infestation persists, the soil can be treated with Bacillus thuringiensis israelensis (BTI), a naturally occurring bacterium toxic only to certain fly larvae. This product provides biological control without harming the plants. Simultaneously, placing yellow sticky traps near plants captures the adult gnats, preventing them from laying more eggs.
If the insects are fruit flies, the breeding source is typically fermenting material in the kitchen. This includes overripe fruit left on counters, food residue in garbage disposals, or unrinsed beverage containers. Immediate action involves cleaning all surfaces, ensuring trash cans have tight-fitting lids, and storing susceptible produce in the refrigerator.
For drain flies, the breeding site is the organic sludge lining the inside of slow or rarely used drains. The most effective method is to physically clean the pipes using a plumbing brush or apply a bio-enzymatic drain cleaner to break down the organic film. A temporary home remedy involves pouring a mixture of baking soda and vinegar down the drain, allowing the foaming action to dislodge the film before flushing with hot water.
Immediate Repellent and Deterrent Strategies
While working to eliminate breeding sources, several immediate strategies can offer temporary relief from adult gnats. One of the most effective non-chemical deterrents is simply using a fan. Gnats are weak fliers, and the slightest breeze makes it difficult for them to navigate or land on a target.
Placing a simple, homemade trap can also quickly reduce the adult population. A small bowl filled with apple cider vinegar, a few drops of dish soap, and a pinch of sugar is highly attractive to many small flies. The vinegar scent lures the insects, and the dish soap breaks the surface tension of the liquid, causing them to sink and drown.
Certain scents can be used to create a barrier that gnats avoid. Essential oils such as peppermint, citronella, or eucalyptus can be diffused or lightly sprayed in an area to deter them. Finally, individuals who are consistently bothered may consider temporarily avoiding personal care products with sweet or fruity fragrances, as these can mimic the fermenting smells that attract the insects.