No-See-Ums in Texas, the Biting Midges You Feel but Cannot See
You are sitting on the patio at dusk, something keeps biting your ankles and arms, and there is nothing there when you look. That is how no-see-ums got their name. They are real flies, small enough to slip through an ordinary window screen. Here is what they are, where they breed, and how to cut them down around your home.
- Also called biting midges, biting gnats, sand flies, sand gnats and punkies.
- An adult is usually 1 to 2 mm long, small enough to fit through a hole in a window screen.
- Most bite at dusk, at night or in the early morning.
- They breed in wet ground, including over-watered lawns and flower beds.
- A standard window screen will not keep them out.
What are no-see-ums?
No-see-ums are biting midges, tiny bloodsucking flies. The University of Florida says they are also called sand flies or sand gnats, that adults are usually 1 to 2 mm long, and that the United States has about 170 species of the main biting group, Culicoides. Only the females bite, because they need blood to develop their eggs.
Under a magnifier a no-see-um looks like a very small, compact mosquito. The University of Arizona Cooperative Extension describes them as small, dark flies, barely visible to the naked eye, and adds a fourth name, punkies. Both males and females drink flower nectar. The males cannot pierce skin, so every bite you feel comes from a female.
The University of Florida IFAS profile of biting midges says most kinds bite at dusk, at night or in the morning. Timing is a useful clue on a Collin County patio: nothing all afternoon, then bites as the sun goes down, points this way, though the University of Florida notes some kinds bite in daylight.
Are no-see-ums gnats?
They are biting gnats, but not the gnats most people mean. No-see-ums are biting midges, a family of true flies, and the University of Florida says only a few groups in that family bite at all. The small flies around houseplants and the fruit bowl are a different problem. If something tiny is biting, suspect a no-see-um.
The name “sand gnat” adds to the confusion, and so does size. A no-see-um is usually 1 to 2 mm long, far smaller than a mosquito, and the University of Florida shows one beside a standard window screen to make the point that it can walk through the holes. If the tiny insects you see are on the kitchen drain or the fruit bowl and nobody is getting bitten, our article on gnats, fruit flies and drain flies will fit better.
Where do no-see-ums come from?
Wet ground. The University of Florida says the larvae need steady moisture and live along the edges of streams, marshes, ponds, puddles and water-filled tree holes. The University of Arizona adds over-watered mulch and lawns, new construction sites, indoor plant pots, and water dripping from air conditioners. The larvae cannot survive drying out, which is the weak spot.
Distance cuts both ways. The University of Arizona says females can travel a little over 1 mile from where they hatch, but that the heaviest biting usually happens close to where they emerge. In a McKinney or Frisco back yard, the likely close-by sources are the creek or retention pond behind the fence, a flower bed the sprinklers keep soaked, and the puddle under the air conditioner’s drain line.
That is why the first step is drying things out. The University of Arizona says holding off irrigation and letting wet spots drain kills the eggs and larvae, and that eggs hatch in 2 to 10 days, and that the whole life cycle varies widely but may run 2 to 6 weeks.
Why are no-see-ums in my house?
They fly straight through the screens. The University of Arizona says no-see-ums pass through standard 16 by 16 or 18 by 16 mesh screens and recommends 30 by 30 mesh instead. The University of Florida says regular window screens do not keep biting midges out. An open door at dusk, or a damp potted plant indoors, adds to it.
Check the inside of the house for a breeding spot as well as the way in. The University of Arizona lists indoor plant pots and water from air conditioners among the places they breed, so an always-wet saucer under a houseplant or a leaking condensate line deserves a look. Keep doors closed as much as you can around dusk, repair any rip in a screen, and replace worn seals and sweeps on the doors you use most.
Screens are the long fix, with the finer 30 by 30 mesh on the doors, windows and porch you use most at dusk. The University of Arizona’s Backyard Gardener sheet adds that a fan helps keep them away from you, and that screens can be treated with an approved insecticide, used as its label directs.
How do you get rid of no-see-ums in your yard?
Dry out the places they breed, then keep them off you. The University of Arizona says to hold off watering near where the bites happen and let wet spots drain, which kills eggs and larvae. The University of Florida says a study of a bifenthrin barrier spray at the maximum label rate reduced the numbers of one coastal species.
Start with water you control. Water the lawn and beds less often, fix the sprinkler head that keeps one corner soggy, empty saucers and buckets, and run the air conditioner’s drain line to a spot that dries. The University of Florida adds a caution: in one study, removing the ponds that were thought to be the main breeding site did not reduce the adults, which the authors say shows how poorly understood the breeding places of some kinds still are.
The University of Arizona says spraying for the larvae is not a practical option, because their breeding sites are scattered and hard to reach. So the yard work, good screens, a fan blowing across the patio seats and a repellent on your skin do most of the job. Our article on no-see-um bites and the repellents that help covers the last part.
Are no-see-ums dangerous?
For people here, mostly a nuisance. The University of Arizona says the main medical issue is allergic reactions to the bites. The University of Florida says biting midges carry diseases of livestock and deer in the United States, such as bluetongue, and spread human diseases in parts of South America and Africa. For animals, the risk is real.
That livestock risk matters if you keep sheep or cattle, or live near deer on the edge of Collin County’s farmland. The University of Florida says the bluetongue and epizootic hemorrhagic disease viruses that biting midges carry kill animals every year and cost ranchers and farmers millions of dollars, and that horses can develop an allergic skin condition, called sweet itch, from the bites.
For a person, a strong reaction to the bites is the thing to watch. If bites swell badly, blister, or you feel unwell, see a doctor.
No-see-ums and their look-alikes, told apart
The no-see-um column comes from the University of Florida IFAS and the University of Arizona Cooperative Extension. The mosquito column is general background, for comparison.
| Question | No-see-um | Mosquito |
|---|---|---|
| Size | Usually 1 to 2 mm | Many times larger, easy to see |
| Gets through a window screen? | Yes, through standard mesh | No, a standard screen stops it |
| Who bites | Females only | Females only |
| Breeds in | Wet soil, mud, soggy mulch | Standing water |
| When it bites most | Dusk, night, early morning | Varies by kind |
A bite you feel from a fly you cannot see is the no-see-um.
What Pest Me Off does about no-see-ums
When you call us about bites you cannot explain in a McKinney, Allen, Frisco or Plano home, we identify the insect before anything else. No-see-ums, also called biting midges or biting gnats, are not the same as every little fly people call a gnat, and a bite alone does not tell us which pest it was.
Then we inspect for moisture, entry points and where the activity is outside: irrigation leaks, the soggy beds and lawn corners, the air conditioner’s drain line, and the screens and door seals they come through. We address those conditions, and when treatment is warranted we target the places where they rest. We work on your own yard and the conditions you control, and we explain what we found and what we recommend before any work is done.
You can help before we arrive. Note where and when the bites happen, keep a photo or one of the insects if you can catch it, make sure we can reach the yard and the rooms involved, and tell us about any earlier treatments. If we apply anything, we give you specific instructions for getting ready and for when you can go back out. Our no-see-um control page explains the service.
Bitten on the patio by something you cannot see? Same-day pest control in McKinney and the surrounding cities when you call before noon.
We ask where and when the bites happen and look at the yard before we recommend anything. Free inspection and estimate.
