Do Mosquito Lawn Sprays Work?

We’ve all been there. It’s a beautiful summer evening on the deck or in the backyard. Then the mosquitoes crash the party.

Some people break out repellents to ward off the flying bloodsuckers, but it often takes a more strategic plan to create a mosquito-free zone. Mosquito lawn sprays are important tools in reclaiming your backyard.

Daniel Markowski, Ph.D., a technical advisor for the American Mosquito Control Association, uses sprays for his backyard. “You should do something, but do it properly and do it safely,” he says.

What Are Mosquito Lawn Sprays?

Mosquito lawn sprays feature liquid pesticides, whether natural or chemical, applied to areas where mosquitoes rest. This allows homeowners to reduce mosquito numbers where they and their guests spend the most time.

Foggers are a variation of a mosquito spray, creating a mist that settles into the grass and other areas. But there’s one key difference between them. Foggers dispense short-term pesticides that take care of the situation temporarily, while the chemicals in mosquito lawn sprays tend to work longer.

Why Spray at All?

According to the Centers for Disease Control and Prevention (CDC), mosquitoes are “the world’s deadliest animal,” with more than one million people dying from diseases they spread each year.

In the United States, roughly 2,400 people annually contract West Nile virus. According to Markowski, there have been reports of Eastern equine encephalitis in North Florida and dengue fever in South Florida. So mosquitos can be much more than an annoyance.

Ways to Apply Lawn Sprays

Mosquito lawn sprays can be applied a few ways. For small spaces, you can choose handheld spray bottles or pump sprayers (similar to devices that spray herbicides), or a device attached to the garden hose. Larger spaces may require a backpack sprayer.

For a more hands-off way, you could hire a mosquito spraying business or install a professional-level misting system. Although both are convenient, a non-targeted approach could overuse pesticides, potentially harming the environment, pets and people.

Is It Safe for Beneficial Insects?

In many cases, no. Most pesticides are broad spectrum, meaning they indiscriminately kill any insect, Markowski says. So be smart about where you apply it.

“Don’t spray the entire yard,” he says.

Because mosquitoes rest during the day, he says, look for shaded areas out of the direct sunlight, and spaces protected from the wind. “If you keep that in mind, spray where you think they’ll be resting,” he says. Although Markowski says he sprays his yard frequently, he still enjoys beautiful butterflies and other pollinators in his gardens.

Pick the Right Pesticide

Mosquito lawn sprays generally use natural or synthetic pesticides, as well as essential oils. The key is choosing a spray that works well on mosquitoes with little impact on beneficial insects.

“Generally speaking, you need a good pesticide in the product,” says Markowski. “But a lot of people don’t like classic pesticides.”

Pyrethrins are natural insecticides derived from the dried flower heads of Chrysanthemum cinerariaefolium. These are often popular because they degrade within a day, but less effective for long-term efficacy.

Markowski noted pyrethroids, aka synthetic pyrethrins, work well because they’re effective for days or weeks. The same holds true for permethrin, also derived from pyrethrins.

How Well Do Essential Oils Work?

Not very.

“None have truly been tested for efficacy,” Markowski says.

“Watch out for the 25b [as listed in the Federal Insecticide, Fungicide and Rodenticide Act] products. They are exempt from EPA [Environmental Protection Agency] registration and aren’t tested very well to see whether they are safe and effective.”

If a product claims to kill everything except beneficial insects, Markowski says, steer clear. “Watch out for any products that make wild promises,” he says.

Know Your Mosquitoes

While most of us think all mosquitoes are the same, there are roughly 2,700 species throughout the world — 176 in the United States.

“In any given area you can have 30 to 40 different species,” says Markowski. It’s good to know the differences, he says, because there are nuances in lifecycles and behavior. When you know how the mosquitoes in your region operate, you can better combat them. He recommends speaking with your local mosquito office to learn more.

How and Where to Use Mosquito Lawn Spray

The key is thinking like a mosquito and evaluating where they might land. “Once it gets dark, they start to fly around, but even at night, they rest a lot,” Markowski says. This includes shaded areas along fences and protected space around the home.

Start by spraying the back of the house around the doorways, as well as underneath the eaves. “Spray closest to where you spend time,” he says. “If you have a deck, spray underneath it.”

Don’t forget under the table and chairs, either. “They duck under these dark places to rest, then come out to get your legs,” he says. “If you do that, you’ll see a lot you fewer mosquitoes.”

Is There a Risk to Pets and People?

If pets are directly exposed to pyrethroids or similar compounds, they might experience vomiting, diarrhea and other unpleasant symptoms. Keep pets out of the yard while you’re spraying. Once the spray dries, which typically takes half an hour, you can let them back in.

Are Mosquito Lawn Sprays Bad for the Environment?

If used improperly, yes. When spraying, always read and precisely follow the instructions on the label to keep pollinators safe and reduce your impact on the environment.