No-see-ums are a persistent biting pest across much of Texas, especially along the Gulf Coast and in areas with moist soil or standing water. These tiny flies, technically called biting midges, are small enough to pass through standard window screens and deliver bites that burn far out of proportion to their size. If you live in or are visiting Texas, here’s what you need to know about when they’re active, how to protect yourself, and how to treat bites when they happen.
What No-See-Ums Actually Are
No-see-ums belong to the family Ceratopogonidae, a group of biting midges found worldwide. They earn their nickname honestly: adults measure just 1 to 3 millimeters long, small enough that you often feel them before you see them. Only the females bite. They need blood as a protein source to develop their eggs.
Their mouthparts contain four microscopic cutting blades inside a fleshy sheath. Rather than piercing the skin like a mosquito, they lacerate it, which is why the initial bite produces a sharp, burning pain that feels disproportionate to the size of the insect. You may see dozens on your skin at once during a heavy swarm, though their gray-brown coloring makes them easy to miss.
Where and When They’re Active in Texas
The Gulf Coast region, stretching from the Galveston area down through Corpus Christi and west toward the Rio Grande Valley, is prime no-see-um territory. Coastal marshes, tidal flats, and the sandy soils along bays provide ideal breeding habitat. But no-see-ums aren’t limited to the coast. Anywhere in Texas with consistently moist soil, ponds, slow-moving streams, or poorly drained land can support breeding populations.
In southern and coastal Texas, no-see-ums are active for much of the year, not just summer. Spring through early-to-mid fall brings reliable activity, with the national peak falling in June and July. They’re most aggressive in the early morning and late evening hours, which coincides with the times many Texans head outside to avoid midday heat. On overcast, humid days they may bite throughout the afternoon as well.
How Bites Feel and Progress
The initial bite is a sharp, burning sting. After that, reactions vary widely from person to person. Some people develop a small reddish welt that fades within hours. Others experience a significant allergic response: swollen, red bumps several centimeters across that itch intensely for days or even weeks. In more severe cases, bites can blister and become weepy.
One tricky aspect of no-see-um bites is that the itching doesn’t always start immediately. Some people won’t notice anything for several hours after being bitten, which makes it hard to pinpoint when and where the exposure happened. If you’ve moved indoors and suddenly develop clusters of itchy welts on exposed skin, no-see-ums from your evening walk are a likely culprit.
People who live in areas with heavy no-see-um populations often become desensitized over time, eventually experiencing only mild reactions or none at all. Visitors and newcomers to Texas tend to react more severely, which is why tourists along the coast are frequently caught off guard.
Health Risks Beyond the Itch
In the United States, no-see-ums are not known to transmit diseases to humans. The primary health concern is the bite reaction itself. For most people, the pain and itching are the beginning and end of the problem. However, scratching aggressively at bites can break the skin and introduce bacteria, leading to secondary infections. This is the main complication worth watching for: bites that become increasingly red, warm, swollen, or that develop pus rather than improving over a few days.
Repellents That Work
DEET remains the most reliable repellent against no-see-ums and is explicitly effective against biting midges. Products with higher DEET concentrations last longer, though concentrations of 20 to 30 percent are sufficient for most outdoor activities in Texas.
Picaridin is another strong option that works well against biting midges and has a lighter, less oily feel than DEET. It’s also effective against chiggers, which is a useful bonus in Texas. Oil of lemon eucalyptus (the active ingredient is PMD) provides protection comparable to low-concentration DEET products, and several commercial formulations specifically list no-see-ums on the label. It’s the best-studied plant-based option available.
Whatever you choose, apply it to all exposed skin. No-see-ums bite any uncovered area, and their small size means they’ll find gaps in coverage that a mosquito might miss.
Keeping Them Out of Your Home
Standard window and door screens do not stop no-see-ums. The mesh openings are large enough for these insects to fly right through, which is why you may find yourself getting bitten indoors with the windows “screened.” Specialty no-see-um screening uses a much finer mesh, typically 20×20 or finer, with apertures small enough to block midges. Several manufacturers produce fiberglass and aluminum versions in this finer mesh, available in widths from 36 to 96 inches for standard windows and patio enclosures.
The tradeoff is reduced airflow and slightly lower visibility compared to standard screening. Fiberglass no-see-um screen at 20×20 mesh has about 45 percent openness (versus roughly 60 percent for standard screens), so you’ll notice the difference, particularly in enclosed porches. Aluminum versions at 24×22 mesh offer somewhat better visibility. If you live in a high-activity area along the Texas coast, the tradeoff is usually worth it.
Ceiling fans and portable fans also help. No-see-ums are weak fliers, and even moderate air movement makes it difficult for them to land and bite.
Reducing Populations Around Your Yard
No-see-um larvae feed on decaying organic matter in mud, wet soil, and the margins of standing water. Eliminating every breeding site on your property is often impractical, since larvae can develop in surprisingly thin layers of damp soil or in areas you may not control, like neighboring marshland or drainage ditches. That said, reducing moisture helps. Fix leaky outdoor faucets, improve drainage in low spots, and clear accumulated organic debris from areas where water collects.
Along the coast, removing seaweed and organic material that washes up and gets trapped in low-lying areas reduces local breeding sites. Chemical sprays, including foggers and misting systems, provide only temporary relief against adult no-see-ums because new adults quickly move in from surrounding areas once the spray dissipates. They’re not a lasting solution, though some Texans use timed misting around patios for short-term comfort during outdoor events.
Treating Bites
For mild bites, a cold compress and over-the-counter hydrocortisone cream reduce swelling and itching. Antihistamine tablets can help if you’re dealing with multiple bites that are keeping you up at night. Resist the urge to scratch: bites that get scratched open are the ones most likely to blister, weep, and potentially become infected.
If bites swell significantly, blister, or persist beyond a week or two, a stronger topical steroid from a pharmacist or doctor can speed recovery. Severe reactions are more common in people encountering no-see-ums for the first time, so if you’ve recently moved to coastal Texas or are visiting during warm months, be prepared for a stronger response than the locals seem to experience.