How to Get Rid of Sand Gnats | Coastal Pest Plan

Getting rid of sand gnats (biting no-see-ums) requires stopping their outdoor breeding cycle with moisture control and fine-mesh screens, then using personal repellents like 30% DEET for protection.

For the full breakdown, see our best Horticultural Sand For Gnats guide.

The “sand gnat” along the US coast is the biting midge — a tiny, blood-hungry pest that sails through standard window screens and breeds in damp sand. Unlike the fungus gnats that thrive in overwatered houseplants, sand gnats live and breed outdoors. A successful plan pairs habitat modification with the right repellents. The section below covers what to use on yourself, how to fix your yard, and what to do if they still get inside.

Personal Protection: What Repellents Actually Work

DEET is the proven standard for no-see-ums. The effective concentration for adults is at least 30%, and it should be reapplied every two to three hours. Apply it to both skin and clothing — relying only on skin application misses the gnats that land on fabric. Loose-fitting, light-colored clothing also discourages bites; avoid vibrant colors, which attract sand gnats. In high-density areas, a head net offers complete face protection.

Picaridin and oil of lemon eucalyptus are effective alternatives. The old standby Skin So Soft provides temporary relief but doesn’t last as long as DEET. Natural oils — citronella, eucalyptus, lavender, orange peel, and lemon — can be used as candles, sprays, or topical oils for lighter exposure.

Outdoor Prevention: Removing Their Breeding Ground

Sand gnats breed in moist, sandy soil and decaying organic matter. Hit their lifecycle by controlling moisture in your yard. Clean clogged gutters, empty flowerpots and bird baths, and fix outdoor plumbing leaks. Avoid overwatering garden beds, and limit dense vegetation near the house to increase airflow between plants. Mow grass short, rake leaves, prune dense shrubs, and remove fallen fruit regularly.

Standard 16-mesh window screens are useless against these pests — they’re literally called “no-see-ums” because they slip through. Seal cracks around vents, eaves, and cable entries with caulk, and turn off non-essential outdoor lights at night — gnats are drawn to the glow.

This step cuts down the gnats that emerge from the soil edge against your house.

Indoor Removal When Gnats Get Inside

If sand gnats have made their way indoors, vacuum every nook and corner — walls, floors, ceilings, and window panels. This physically removes both adults and eggs. Follow up with steam cleaning all areas; sand gnats cannot survive high heat. For carpeted zones, sprinkle salt on the carpet 24 hours before vacuuming to dehydrate and kill them. Boric acid around garbage cans and diatomaceous earth in moist, sandy areas work as long-term chemical controls. When using any insecticide, keep children and pets away for one to two hours after spraying.

Common Mistakes That Sabotage Control

The most frequent error is confusing sand gnats with fungus gnats from houseplant soil. Hydrogen peroxide drenches or sand topping for potted plants will not address a biting midge problem — they are a different species breeding in the yard. Another mistake is keeping standard screens; no-see-um screens are non-negotiable for coastal homes. Finally, understand that these gnats are most active during calm, evening hours — planning outdoor events during this window invites bites no matter what repellent you wear.