Annoying Black Gnats
Q. I have been gardening for 19 seasons. For the first time last year, I was swarmed with biting gnats that leave me with wounds that resemble small pox and itch like the dickens. I now have to wear a net on my head to work in the yard most days, especially when using my reel mower. I wondered if you had any similar observations from others. Thanks,
- ---Regina in Roxborough
A. Yes, Regina—from just about every other gardener in America! Gnats are one of the biggest annoyances we have to face. Our only question to you is: What did you do to avoid them for those first 18 years??!!
Q. We have three acres in the country; one acre is a lawn we keep cut short; the rest is woods. We have a terrible time with gnats; they're driving us crazy, attacking us just about every time we go outside. I love where we live, but it's a real drag not being able to work in the garden or go for a stroll without long sleeves, long pants (in the summer!), hats and sunglasses.
- ---Nickie in Mercersburg, PA
A. Stop cutting the lawn short. Although some gnats breed in tall wet plantings, a super-short cut—which will destroy your lawn over a hot summer—is not the answer. Keep it cut at three inches; use a brush cutter to attack nearby overgrown areas at the edge of the woods; and keep the lawn as dry as possible. The roots of a three inch high lawn can hold massive amounts of water, allowing you to keep the top of the soil dry without any drought stress. And gnats have NO interest in dry topsoil.
Q. Is there any way to control gnats outdoors without killing beneficial insects and fish? Sometimes they take all the joy out of gardening.
- ---Jerry in Beulah, Michigan
A. Sometimes? Sometimes?! These creatures are annoying every hour 7-11 is open, sucking the joy out of gardening worse than any pest except maybe chiggers. In the 'nuisance insect Olympics' they have a darn good chance of bringing home the gold.
The term 'outdoor gnat' can refer to a variety of different creatures, all in the fly family (as are mosquitoes). All breed in water; some in standing water like mosquitoes, and some in running water like the stream that flows right past our house. Some are relatively harmless, and a few are beneficial: pollinating flowers and attacking true pests. But the females of some types are blood-suckers—again, like mosquitoes. And the ones that bother ME the most are 'eye gnats'; tiny black midges attracted to the natural secretions that keep our eyes lubricated and healthy.
To cut their gnatty numbers, drain all standing water on your property. Don't forget those out-of-sight gutters; they are prime breeding sites. Treat standing water that can't be drained (like vernal pools and garden ponds) with BTI—this natural and non-toxic larvacide prevents the breeding of all flies that spawn in water (including mosquitoes) without harming anything else. It's available by mail order and at retail in donut-shaped 'dunks' and in granular form. Here in PA, the local EPA sprays a liquid form from helicopters into the nearby woods and streams to help keep blackfly numbers down.
Keep grass cut at the correct length for your area and keep it as dry as possible. If you water every day, you WILL have lots of gnats (and your plants will have short, sickly root systems). Keep brushy areas near your home well-mowed. Prune or remove plants to make sure lots of light gets in; a tangled shady jungle will breed gnats like mad.
When you want to sit outside in a non-screened area, direct an oscillating fan to keep the air moving away from you; their tiny wings can't fight past it. Place little jars of vinegar around to lure and trap them. Yellow sticky traps also work well.
Years ago, I tested a propane-powered mosquito trap. Early in the season the capture net was filled with black gnats, presumably the biting kind as they were lured to their death by carbon dioxide they thought I was exhaling. I loved emptying that net every day!
When working outdoors, wear clothing that you've treated with a .5% permethrin spray; see our previous articles on ticks for more info about these highly effective repellants. To keep gnats off your face, wear a treated collared shirt with the collars pointed up and a treated fabric hat. And if they still go for your poor eyes, protect your face with one of the non-toxic mosquito repellants that medical studies have found to be as effective as the highly dangerous chemical repellant DEET: "Bite Blocker" (which Gardens Alive sells as "Sting Free") and 'Repel Lemon Eucalyptus'.
I would not call anyone crazy for wearing one of those veiled hats that uses a mosquito netting-type material to cover the face. I would call that person a little uncomfortable on hot days but otherwise blissfully happy.
Buy one of those pith helmets that has a built-in solar powered fan designed to give the wearer a cooling breeze. Maybe try turning the fan around if it doesn't otherwise blow them away. Wear yellow sticky traps on your hat to attract them to a colorful doom.
And finally, a listener once suggested tucking a few wild onion or wild garlic plants behind each ear when you're out weeding those otherwise aggravating little plants. Apparently, gnats are not fans of the strongly scented wild alliums.