Chicago health officials just reported the first death of 2026 due to the mosquito-borne West Nile virus, signaling the threat the pests pose even as summer winds down.
The city has sprayed to kill mosquitoes in 15 communities this year. The threat of West Nile has ranged from moderate to very high this summer. The virus, also detected in the suburbs, can infect many people who may have mild flu-like symptoms or none at all. However, it can be deadly in older adults and anyone with a weak immune system.
There are a number of effective precautions to take, ranging from well-tested repellents to ward off biters and steps that should be taken by everyone to stop the mosquito population from growing.
Read the repellent label
It’s key to understand the active ingredient in any repellent. Use sprays or balms that have at least 30% of an ingredient approved by the U.S. Environmental Protection Agency, experts say.
DEET, picaridin and lemon eucalyptus oil are common EPA-approved chemicals that are effective.
Read the labels to make sure the product is safe for very young children.
“The baseline is it has to be EPA-registered. If it’s registered, it’s been tested for safety,” said Justin Harbison, a Loyola University associate professor of public health and a mosquito researcher.
He acknowledges parents may be uneasy about putting chemicals on babies and toddlers. For children under 2 years old, it may be best to keep them inside when mosquitoes are most active around dusk and dawn, he said.
Do not spray pets with products designed for humans. Consult a veterinarian on how to protect dogs and cats.
You can also treat clothes with permethrin, a chemical that keeps mosquitoes away. The chemical usually lasts until the treated clothes are washed about six times.
Dump all standing water
Mosquitoes need standing water to lay their eggs. Even the smallest amount of water, including a tiny bit in a saucer under a flower pot, can attract a mosquito that can lay 200 eggs at a time.
Bird baths and rain barrels can be treated with a “larvicide,” which is an insecticide that targets mosquitoes in their early stages. These chemicals can be purchased at hardware or home improvement stores.
A rainy summer in spring means extra precautions should be taken.
Don’t count on citronella, marigold and other plants
Citronella candles are a popular product for keeping mosquitoes at bay, but Harbison said they are not very effective.
The pests don’t like the smell, “but does it overcome their desire to come bite you? You may need a whole lot of candles,” Harbison said.
A fan may be a better option because mosquitoes are too light to navigate through the wind.
“They don’t do well with breezes,” Harbison said.
It’s the same reason a breezy beach usually doesn’t have a lot of mosquitoes.
Marigolds and other plants are not a strong enough repellent for mosquitoes, he said.
Stay inside
Mosquitoes need water, but they also like the warm weather. The mosquito season used to be shorter, but as higher temperatures are becoming more the norm in spring and fall, there’s more risk of the bloodsuckers earlier and later in the year.
Until temperatures cool, September may be an active month for the pests.
“The nighttime temperatures are high. Maybe this is a good time to stay inside and watch Netflix,” Harbison said.