For both gnats and mosquitoes, the most reliable plant-based active is 8 percent PMD (oil of lemon eucalyptus). PMD is CDC-recognized against mosquitoes and provides moderate deterrence against most biting gnats and flies. For heavy gnat conditions like Maine or Minnesota black fly season, 20 percent picaridin or 25 percent DEET works better than any natural option. The "natural gnat repellent" market is full of weak essential oil blends, so check the active ingredient label carefully.
This guide covers which biting insects fall under the umbrella of "gnats," what actually works for plant-based protection, and what to do when natural is not enough.
What "gnat" actually means
"Gnat" is a casual term that covers several different biting insect families:
• (Simuliidae): the most aggressive biting "gnats" in North America, swarm at certain times of year (May to July in Maine, Minnesota, Adirondacks)
• (Ceratopogonidae): tiny, almost invisible, painful bites, coastal and lakeside areas
• : another name for some black fly species
• (Phlebotominae): can transmit disease in tropical areas, less common in US
• : small, annoying, but do not bite
When most people say "natural gnat repellent" they usually mean some combination of biting midges, black flies, or no-see-ums.
What works against gnats and mosquitoes
8 percent PMD (oil of lemon eucalyptus)
PMD is the only CDC-recognized plant-based mosquito repellent. Its effect on gnats is moderate. Lab and field studies show PMD provides decent protection against most biting midges and black flies, though not as long-lasting as against mosquitoes. Expect 2 to 4 hours of gnat protection from a typical 8 percent PMD spray, compared to 4 to 6 hours of mosquito protection.
For typical backyard or hiking situations where you encounter occasional gnats alongside mosquitoes, PMD covers both adequately.
20 percent picaridin
Picaridin works well against gnats, no-see-ums, and biting flies. Outdoor publications including Backpacker and REI specifically recommend 20 percent picaridin for black fly and no-see-um conditions. 8 to 12 hours of protection.
This is the default recommendation when natural is not a requirement but mosquito-feel and material safety still matter.
25 to 30 percent DEET
DEET is the most effective option against gnats, especially black flies. For Maine or Minnesota black fly season, 30 percent DEET is the standard recommendation. The trade-offs (skin feel, fabric damage) are usually worth it when you are otherwise being eaten alive.
Permethrin on clothing
Permethrin treats clothing rather than skin and works against gnats, mosquitoes, ticks, and most other biting insects. The combination of permethrin-treated clothing plus a CDC-recognized topical on exposed skin gives the strongest overall protection against multi-pest environments.
What does not work well
Citronella candles
Effect on gnats is minimal. The smoke from the candle wax provides slightly more deterrent than the citronella itself. Maybe usable on a still summer evening for very light gnat pressure. Useless in real black fly conditions.
Essential oil sprays (lavender, eucalyptus, peppermint blends)
Brief deterrent effect under 1 hour at most. Many "natural gnat repellent" products on the market are based on these blends and overpromise.
Ultrasonic devices
No peer-reviewed evidence of effect against gnats or mosquitoes.
Mosquito-repellent plants
Decorative. Will not deter gnats.
Where gnats are worst (and what to bring)
Northeast US in spring (Maine, Vermont, New Hampshire, Adirondacks)
Black fly season runs roughly mid-May to early July. The black flies are aggressive, swarm in daylight, and bite faces and necks despite repellent on lower body. Recommended kit:
• Permethrin-treated clothing
• 25 to 30 percent DEET or 20 percent picaridin on exposed skin
• Head net for fishing or hiking
• 8 percent PMD as a backup for lighter days
For a family camping trip during black fly season, a head net for kids is often the most practical defense.
Minnesota and the Great Lakes
Black fly season is similar to the Northeast. Add to the kit:
• Long pants tucked into socks
• Permethrin on socks and shoe canvas
• Indoor breaks during peak swarm hours
Florida and Gulf Coast (no-see-ums)
Biting midges or no-see-ums are tiny and can bite through some fabrics. Recommended:
• 20 percent picaridin or 8 percent PMD on exposed skin
• Tight-weave clothing
• Fine-mesh window screens (no-see-ums can get through standard 16-mesh)
• Avoid the beach at dawn and dusk
Pacific Northwest
Black flies are present but milder than Northeast. Standard 8 percent PMD or 20 percent picaridin usually adequate.
Backyard gnat problems (drain flies, fungus gnats)
These do not bite. They are nuisance flies attracted to overwatered houseplants or drains. Treat the source:
• Let houseplant soil dry between waterings
• Pour boiling water down rarely used drains
• Reduce indoor moisture
A repellent spray will not solve a drain fly or fungus gnat problem because they are nuisance flies, not biters.
What about "natural gnat repellent" products on the market
Most products marketed specifically as "natural gnat repellent" use blends of:
• Citronella
• Peppermint
• Cedarwood
• Geraniol
• Soybean oil
These have brief (under 1 hour) deterrent effects in lab studies. Skin So Soft (Avon's original "bug repellent" lore) became famous as a gnat repellent because of its mineral oil content rather than any specific repellent active. It works very briefly through skin moisture, then evaporates.
For real protection in heavy gnat conditions, none of these natural blends substitute for a CDC-recognized active.
Common questions about natural gnat and mosquito repellent
What is the best natural gnat repellent?
8 percent PMD (oil of lemon eucalyptus) is the only plant-based active backed by CDC efficacy data against mosquitoes and shown to provide moderate gnat deterrence. Higher concentrations (20 to 30 percent PMD) extend duration but require older minimum ages.
Does Skin So Soft really repel gnats?
The original Avon Skin So Soft Bath Oil has a brief deterrent effect on some gnats through skin moisture, but the effect lasts under 1 hour. Avon's actual repellent product (Skin So Soft Bug Guard) uses IR3535 or picaridin and works much longer.
What about apple cider vinegar?
Apple cider vinegar attracts certain fruit flies (which is why traps use it) but does not repel gnats from your skin. It is not an effective topical repellent.
Do mosquito repellents work on no-see-ums?
CDC-recognized actives (DEET, picaridin, PMD, IR3535) work on no-see-ums with varying effectiveness. 20 percent picaridin or 25 percent DEET is the strongest. Tight-weave clothing helps too because no-see-ums can sometimes bite through loose fabric.
Can I use natural gnat repellent on kids?
Yes, with the same age guidelines as for mosquitoes. PMD-based products from Superbloc are labeled safe from 6 months. Most other PMD products require 3 years.
Will essential oil diffusers keep gnats out of my house?
Lavender, eucalyptus, or peppermint diffusers may create a mildly unpleasant environment for some gnats but will not prevent infestation. If you have an indoor gnat problem, treat the source (overwatered plants, drains) rather than relying on repellent.
Are gnats attracted to certain people more than others?
Yes, similar to mosquitoes. Black flies and biting midges respond to carbon dioxide, body heat, and skin odors. Pregnant women and people with type O blood tend to attract more bites.
Browse Superbloc
• 8 percent PMD spray works on mosquitoes and provides moderate gnat protection.
• 2 sprays plus 2 wipes packs for the whole family.
For heavy gnat conditions (Maine black fly season, Pacific Northwest Spring), also consider Sawyer Picaridin Lotion 20 percent or a head net for the most aggressive days.
Featured in goop and Harper's Bazaar.
Written by Tanya Lee, Founder, Superbloc
