The most effective way to stop no-see-ums from biting is a combination of the right repellent, physical barriers, and timing your outdoor activities around their peak hours. No-see-ums are tiny biting midges, often less than 3mm long, that thrive in humid, coastal, and marshy areas. Their size makes them harder to keep out than mosquitoes, but a layered approach works well.
Best Repellents for No-See-Ums
Not every insect repellent works equally well against no-see-ums. Three active ingredients have proven effectiveness against biting midges specifically.
DEET is the most reliable option. It works well on biting midges, black flies, fleas, and mosquitoes. Higher concentrations last longer, but officials recommend capping use at 30 percent DEET. A product in the 20 to 30 percent range gives you strong, sustained protection without diminishing returns.
Picaridin is equally effective against no-see-ums and chiggers. It feels lighter on skin than DEET, doesn’t damage plastics or synthetic fabrics, and comes in both spray and lotion forms. Products with higher picaridin concentrations (typically 20 percent) also cover ticks, making them a good all-around choice if you’re outdoors in areas with multiple biting pests.
Oil of lemon eucalyptus (PMD) is the plant-based alternative. Products with 8 to 10 percent PMD do list no-see-ums on their labels. However, testing showed it provided protection similar to low-concentration DEET only during the first few minutes, then dropped off significantly. If you prefer a botanical repellent, expect to reapply frequently.
Use Moving Air to Your Advantage
No-see-ums are weak fliers. They’re most active under calm conditions, which is why bites tend to happen during still evenings near water. Even a moderate breeze makes it difficult for them to land on you. A ceiling fan on a porch or patio creates enough airflow to keep them at bay. If you’re sitting outside, a portable fan pointed at your seating area is one of the simplest and most effective deterrents available, no chemicals needed.
Screen Mesh That Actually Blocks Them
Standard window and door screens have openings large enough for no-see-ums to pass right through. If you live in a coastal or marshy area and they’re getting inside your home, you need a tighter weave. No-see-um screening uses a 20×20 mesh, meaning 20 threads per inch in each direction, creating openings small enough to block midges, gnats, and sand flies.
This finer mesh does reduce airflow slightly compared to standard screens, so it’s a tradeoff. Many people install it only on the side of the house closest to the breeding habitat (marshes, mangroves, standing water) and keep standard screens elsewhere. It’s available as fiberglass rolls you can install yourself in existing screen frames.
Clothing and Timing
No-see-ums bite exposed skin, so covering up is straightforward protection. Long sleeves, long pants, and closed-toe shoes reduce the surface area available to them. Light-colored clothing helps you spot them and tends to attract fewer biting insects than dark clothing. Loose-fitting fabrics work better than tight ones because no-see-ums can sometimes bite through thin, stretched material pressed against skin.
Timing matters too. No-see-ums are most active at dawn and dusk, particularly on warm, humid, windless days. If you can shift your outdoor activities to midday or wait for a breezy period, you’ll encounter far fewer of them. After a rain, when the air is still and humidity is high, expect peak activity.
Reduce Breeding Sites Near Your Home
No-see-ums breed in moist organic matter: wet soil, decaying leaves, the edges of ponds or marshes, and even the moist soil in overwatered flower beds. While you can’t drain a nearby marsh, you can reduce their numbers close to your home by eliminating unnecessary standing water, keeping gutters clear, and avoiding overwatering your lawn and garden beds. Even drying out a small patch of consistently soggy ground can make a noticeable difference.
Treating Bites You Already Have
No-see-um bites produce an intense itch that’s disproportionate to the size of the insect. The welts are small, red, and often appear in clusters on exposed areas like ankles, wrists, and the back of the neck.
Start by cleaning the bite with soap and water to prevent infection. A cold compress or ice pack provides immediate itch relief. Over-the-counter hydrocortisone cream (1 percent) resolves the itch quickly, often within an hour. Calamine lotion is another option. For more intense reactions with significant swelling, an oral antihistamine can help reduce the inflammatory response.
The most important thing is to avoid scratching. No-see-um bites are prone to secondary infection when the skin is broken, which can turn a minor annoyance into something that needs antibiotics. If redness and swelling spread outward from a bite site rather than improving, that’s a sign of infection worth getting checked.