DEET and picaridin are the most effective repellents against biting midges, those tiny flies also called no-see-ums, punkies, or midgies depending on where you live. Both active ingredients are specifically registered and tested against midges, and they’re widely available in sprays, lotions, and wipes. But choosing the right product is only part of the equation. Timing, concentration, physical barriers, and even wind all play a role in keeping midges off your skin.
Best Active Ingredients for Midge Repellent
Four active ingredients are registered as effective against biting midges, and they’re not all equal.
DEET remains the gold standard. It works on midges, mosquitoes, black flies, and fleas. Products range from 10% to 100% concentration. Higher percentages don’t repel better, they last longer. A 20-30% DEET product gives several hours of protection and is a good all-purpose choice for midge-heavy environments like coastal marshes, lakesides, or the Scottish Highlands.
Picaridin is the main alternative. It works well on midges and chiggers, feels less greasy than DEET, and won’t damage plastics or synthetic fabrics the way DEET can. A 20% picaridin product offers comparable protection time to a similar DEET concentration. If you dislike the feel or smell of DEET, picaridin is your best swap.
Oil of lemon eucalyptus (PMD) is a plant-derived option that lists no-see-ums, gnats, and black flies on its label. It’s available in towelettes with around 8% PMD. It works, but protection time is shorter than DEET or picaridin, so you’ll need to reapply more frequently.
IR3535 is found in some Avon skin care products and is registered for midges, black flies, gnats, and sandflies. The World Health Organization gives it an excellent safety rating, but its concentrations in consumer products tend to be lower, which means shorter protection windows.
Plant-Based and Natural Options
Bog myrtle oil (also called sweet gale) has a long folk reputation in Scotland, and lab testing backs it up. In controlled experiments, more than eight out of ten midges avoided the scent of bog myrtle when given the choice between treated air and clean air. Field trials were even more dramatic: volunteers wearing a bog myrtle product on one arm stayed bite-free, while their untreated arm attracted around 120 bites within ten minutes.
The catch with most natural repellents is staying power. Plant oils evaporate faster than synthetic ingredients, so reapplication every 30 to 60 minutes is typical. If you’re gardening or taking a short walk, a natural option can work fine. For an all-day hike through midge territory, DEET or picaridin will save you a lot of reapplication.
Citronella candles and wristbands, for what it’s worth, perform poorly against midges in any real-world setting. The concentration of repellent they produce is too low and too diffuse to create a meaningful barrier around your skin.
Physical Barriers and Mesh Size
Biting midges measure just 1 to 3 millimeters long, which means standard window screens and mosquito nets won’t stop them. They slip right through. You need fine mesh with 50 or more holes per inch to block midges, and even at that density, some of the smallest individuals can squeeze through. The tradeoff is that mesh this fine noticeably reduces airflow and visibility, so it’s best used on head nets and tent windows rather than across large openings.
Head nets designed specifically for midges are sold as “no-see-um nets” and are worth the investment if you spend time in areas with heavy midge activity. Permethrin-treated clothing adds another layer of protection. Permethrin is applied to fabric rather than skin, and it both repels and kills insects on contact. A single treatment lasts through multiple washes. Combining a permethrin-treated shirt with DEET or picaridin on exposed skin is the most effective strategy for severe midge environments.
When Midges Are Most Active
Midges thrive in wet, warm conditions. They typically emerge in two main hatchings per season, with the first peak in early to mid-June and a second roughly five to six weeks later. A warm, wet summer can extend their season, and in unusually mild autumns, a rare third hatching is possible. Dry, hot spells suppress midge numbers significantly, but once rain returns, populations bounce back quickly.
Dawn and dusk are peak biting hours. Midges are weak fliers, so even a light breeze (around 5 to 7 mph) grounds them. If you can choose your campsite or outdoor seating, pick an exposed, breezy spot over a sheltered one near still water. A small portable fan pointed at your legs and feet can replicate this effect on a patio or porch.
Safety for Children and Pregnancy
For babies under two months old, skip repellents entirely and use a carrier draped with fine-mesh netting instead. For older infants and children, DEET is considered safe at concentrations under 31%. Oil of lemon eucalyptus and picaridin are not recommended for children under three because young kids tend to rub their eyes and mouths, and these products cause eye irritation. IR3535 has an excellent safety profile and is recommended by the French health ministry as a preferred repellent for older children.
During pregnancy, DEET has the most safety data behind it. Studies of use in the second and third trimester showed no increased risk of birth defects or developmental problems. No first-trimester studies have been published, but animal studies using doses far exceeding normal human exposure also found no birth defect risk. Permethrin-treated clothing is another good option for pregnant women: although permethrin can cross the placenta, absorption from treated fabric is less than one-thousandth of what you’d get from a topical lotion. Oil of lemon eucalyptus and IR3535 lack pregnancy-specific studies, so they shouldn’t be a first choice when other well-studied options are available.
If You Do Get Bitten
Midge bites produce small, intensely itchy welts that can last several days. The most important thing is to avoid scratching, which breaks the skin and invites infection. For immediate relief, rub an ice cube on the bite for about 30 seconds, or apply firm pressure for 10 seconds. Both tricks interrupt the itch signal.
Over-the-counter hydrocortisone cream or calamine lotion applied three times a day works well for persistent itching. A paste of baking soda and water is a simple alternative. If you have dozens of bites or a stronger reaction with widespread swelling, a non-drowsy oral antihistamine like cetirizine or loratadine can bring the inflammation down from the inside. Some people develop increasingly severe reactions to midge bites with repeated exposure over a season, so keeping antihistamines on hand is worthwhile if you live in or frequently visit midge-heavy areas.