You can be having a perfect evening on the beach or the dock and never spot the thing that is biting you. No-see-ums live up to the name. They are tiny biting midges, and their bites can itch far out of proportion to their size. This guide covers what actually keeps them off, why they are trickier than mosquitoes, and how to apply repellent so it holds.
The quick answer
The best bug spray for no-see-ums is a CDC-recognized active applied thoroughly to exposed skin: 8% PMD from lemon eucalyptus for the whole family from 6 months, or picaridin for adults. No-see-ums are smaller and more persistent than mosquitoes, so coverage and reapplication matter more than with a mosquito-only evening.
What are no-see-ums, exactly?
No-see-ums are biting midges, sometimes called sand flies or punkies. They are a fraction of the size of a mosquito, which is why they slip past window screens and go unnoticed until the bites start. They gather near water and damp sand, and they are most active around dawn and dusk, especially in still air. That is why the classic no-see-um moment is a calm evening at the beach, the marsh, or the lake.
Their bites tend to itch more sharply and longer than a mosquito bite, which is the other reason people go looking for real protection rather than toughing it out.
What ingredient works on no-see-ums?
The same CDC-recognized actives that work on mosquitoes are your best defense, applied more thoroughly. The CDC recognizes DEET, picaridin, oil of lemon eucalyptus and PMD, and IR3535 for reducing bites from biting insects. For a plant-based option the whole family can use, 8% PMD from lemon eucalyptus is the one with genuine credentials.
The catch with no-see-ums is coverage. Because they are so small and land in force, any patch of skin you miss becomes a target. The Superbloc Bloc Off Spray uses 8% PMD, is lab-tested for 6-plus hours, and goes on alcohol-free and water-based, which makes it comfortable to apply generously to ankles, feet, and the backs of the knees where midges tend to bite. For beach and travel days, the Bloc Off Wipes make it easy to cover exposed skin evenly without overspray in the breeze.
How to actually keep no-see-ums away
Repellent does the heavy lifting, but a few habits close the gaps:
- Cover the easy-to-miss spots. Ankles, feet, hairline, and the backs of the knees are where no-see-um bites cluster. Apply there deliberately.
- Time it. They peak at dawn and dusk in still air. A breeze genuinely helps, so an open, moving-air spot beats a sheltered corner.
- Reapply after water and sweat. A long beach evening usually means one reapplication.
- Add a light layer. Loose long sleeves and pants at the buggiest hours give the repellent less exposed skin to defend.
Do no-see-ums come through screens?
Often, yes. Standard window screens are sized for mosquitoes, and no-see-ums are small enough to pass through many of them. If they are a regular problem at home, finer no-see-um mesh exists for windows and porches. For an evening out, though, a well-applied CDC-recognized repellent is the practical answer.
Where you will run into them
No-see-ums love warm coastlines and wetlands. Florida beaches, the Gulf Coast, the Caribbean, and Costa Rica are classic territory, which is why a repellent that also handles midges is worth packing for tropical travel. If a beach trip is on the calendar, our Costa Rica travel guide covers the same protect-the-evening approach for a full tropical itinerary.
The bottom line
No-see-ums are small, but they do not have to end your evening. Reach for a CDC-recognized active like 8% PMD, apply it thoroughly to the spots midges target, favor a breezy time and place, and reapply after the water. Then you get to stay for the whole sunset, which is exactly where you wanted to be.
Last updated: 2026-07-06. Sources: CDC guidance on preventing bites from mosquitoes and other biting insects and recommended repellent active ingredients. Verify current label before use.
By Tanya Lee, Co-Founder of The Superbloc.
Related: Best Bug Spray for Costa Rica · Bloc Off Spray