Mosquitoes suck. They’re far worse than pests that can ruin an evening. Zika, West Nile, and other viruses have all been carried by species in the U.S. including the Asian tiger mosquito (Aedes albopictus) and the yellow fever mosquito (Aedes aegypti). These are dangerous diseases and as such mosquitoes should thus be dealt with impunity. Does this mean stocking up on DEET? Yes, but that’s just the first order of the attack. To really take on mosquitoes in a backyard, you need to wage an offensive that disrupts the mosquito populace completely. As Sun Tzu would say, “Attack is the secret of defense; defense is the planning of an attack.” In other words, it’s time to put down the Citronella candle and seek out the source of the beasts. Happy hunting.
The Mosquito Lifecycle
To take the war to mosquitos and win, it helps to understand their lifecycle. “Like all insects, mosquitos have a complex lifecycle, meaning the larval phase is separate from the adult phase,” says Donald Yee, Ph.D., board-certified entomologist and mosquito researcher at the University of Southern Mississippi. “The adults fly around in the environment while the larva can only exist in stagnant water. Though it typically takes one to two weeks, mosquitos can go from egg to adult in five days if it is the proper temperature and there is enough food for the larva.”
Adult female mosquitos require a bloodmeal to produce eggs (that’s why they bite us), then they seek out stagnant water in which to lay their eggs. Swamps and marshes are ideal spots, but any little reservoir they can find around your home will suffice. Kiddie pools and dog dishes are prime targets, but so are the small pools of rainwater that collect in gutters, the catchment dishes beneath potted plants, or in the crevices of kids’ toys left out on the lawn. “Mosquitos can breed in extremely small amounts of water,” says Joseph Conlon, technical advisor to the American Mosquito Control Association. “I’ve found Aedes aegypti breeding in discarded soda bottle caps.”
Once they lay their eggs, the females join the males in nestling into vegetation and hunting for food. “A mosquito’s daily plan is not that complicated,” Yee says. “Oftentimes, they’re just resting in the grass [for safety] because a lot of things can kill them, from spiderwebs to wind to raindrops to excessive heat. Other times, they’re flying around looking for nectar from flowering plants, shrubs or trees.”
How to Get Rid of Mosquitoes Once-And-For All
First of all, DEET works. As a first order of protection, experts recommend applying DEET or picaridin to your body. These are the two most effective chemical repellents against the species that ravage humans and carry disease. Yes, DEET reeks and can damage sunglasses and outerwear, but the stuff works and is actually incredibly safe. Conlon says wearing loose-fitting, light-colored long-sleeved shirts and long pants, along with socks, can deter mosquitos from biting as well.
But these are tactics for a hike, not your yard. To shore up your yard, you need to go hunting — and chemicals won’t cut it.
The fact that adult mosquitos are terrestrial while larvae lie in water is precisely what makes these pests so tough to eliminate. “If you’re only controlling the larva, the adults will just lay more eggs,” Yee says. “And if you’re trying to control adults, you can’t use the same strategy as you’d use on the larvae because it wouldn’t be effective. To really control mosquitos, you need two different strategies.”
This is why both Yee and Conlon strongly advise against hiring an insect-control company to spray your yard with chemicals: It will only kill off adult mosquitos, not the larvae. Plus, these chemicals will eradicate only the mosquitos resting in your own yard, not those that fly over from your neighbors’ untreated yards or the woods abutting your property.
But even more problematic, these insecticides typically don’t discriminate. “Companies spray residual pesticides, which lay on grass and leaves and stay active for a couple of weeks,” Conlon says. “The issue is it’ll kill any [insect] that comes in contact with it, including pollinators and other beneficial insects.” Even though manufacturers’ directions will warn against spraying when flowers are blooming and pollinators are present to prevent damage, “the average person doesn’t follow that guideline,” says Conlon, “and it’s never good to spray pesticides indiscriminately.” Doing so, Yee points out, ultimately harms biodiversity.
In order to effectively minimize the mosquito population on your property, you need to a two-pronged approach to tackle the adults and the larva.
- Eliminate Excess Standing Water
Every three to five days—and after each rainfall—Conlon suggests pacing your property to look for standing water that isn’t there naturally and drain it. Besides the major water collectors like five-gallon buckets and empty plant pots, check for accumulation in less-obvious places such as in the folds of a tarp over a wood pile, in the creases of a grill cover, or on your kids’ swing set and toys left outside. Old tires propped up against garages are also wellsprings of mosquito larvae, as are bird baths. In fact, Conlon says females lay eggs just above the water line in bird baths, so along with emptying them regularly, scrub the entire bowl.
- Clear Gutters and Downspouts
“If you have lots of leaves in your area that can block your gutters so they are no longer functioning, you are going to have stagnant water,” Yee says. “Mosquitos can be rearing offspring above your head.” Along with clearing out gutters periodically, if you have a downspout to move water away from the house’s foundation, clean that too. “If a downspout isn’t properly pitched or angled, it can hold water,” Yee adds. “And because it is dark and cool, mosquitos will fly under there and lay eggs.”
- Try Mosquito Dunks or Bits
If you have water on your property that you can’t or don’t want to drain, such as a duck or koi pond, treat it with “mosquito dunks” or “mosquito bits.” These pelletized larvicides, available at any hardware store or garden center, contain a bacterium called Bti, short for Bacillus thuringiensis israelensis, that mosquito larva feast on. Conlon says that during digestion, the spores release a toxin that kill the larva, stopping new mosquitos from hatching. Yee adds that Bti is very safe, can remain effective for months, and won’t kill species other than mosquitos.
- Keep Grass Short and Weeds Controlled
Because mosquitos can’t regulate their body temperature like mammals, they try to stay out of the sun during the day by lying low. “They like to sit in vegetation, so if you have long grass, weeds, or dense plantings, that’s where they like to hang out,” Yee says. Therefore, the best ways to control the adult population around your home include keeping your grass mowed and your garden tended. Also pull pesky weeds that crop up in cracks in your driveway, sidewalk, and patio.
Regular yard maintenance should be effective, Yee says, but don’t go as far as changing your landscape with mosquito eradication in mind. If you were to get rid of the flowering plants and shrubs mosquitos seek nectar from, for instance, you’d also be stealing nutrition from bees and other pollinators.
- Don’t Bother with “Mosquito-Repelling” Plants
You might read online that catnip, lemongrass, and other plants repel mosquitos naturally so planting them could help clear your yard. We like the idea, but unfortunately, both experts say there is no scientific evidence behind it. “There is no real natural reason why a plant would repel a mosquito because they are hosts for mosquitos,” Yee says. “If anything, plants attract them because they are pollinators.”
Even geraniums, the source of some repellents, would only deter mosquitos if you crushed up the leaves to release the oils, says Conlon. “Also remember that out in the yard, breezes will waft away any repellency plants would have so you wouldn’t have the oils in the necessary concentrations,” he adds. Even with citronella, widely used in repellant candles, Yee it’s most likely the smoke, not the smell, that drives mosquitos away.