Protecting Against Mosquito-borne Diseases – without Harming Pollinators
By Leslie Cameron, Extension Master Gardener
We often think of mosquitoes as a nuisance that keeps us from enjoying the outdoors, but in addition, and importantly, mosquitoes can transmit disease. Mosquito-borne diseases have been in the news recently, including cases of eastern equine encephalitis (EEE) that were transmitted to humans (though EEE transmission to people remains rare). Dr. Anthony Fauci, former director of the National Institute of Allergy and Infectious Diseases, was diagnosed with West Nile virus in 2024. For the first time in 20 years people in the United States have developed locally transmitted malaria (i.e., transmission not related to travel outside the country), including four people in Florida and one person in Texas in 2023. A case locally of transmitted malaria was reported in Maryland. (Most malaria cases in the United States are related to travel outside our borders, and locally transmitted malaria remains rare.)
Experts believe a warming climate is linked to a lengthening mosquito season. Warming temperatures can accelerate mosquito life cycles, allowing for more reproductive cycles, and can expand mosquitoes’ geographic range.
Weather extremes like heatwaves, rain, and flooding can provide favorable conditions for breeding. While transmission of some of the most serious diseases is not common, it is important to take steps to protect ourselves, families, and pets.
But there are steps we can take without harming pollinators:
However, before reaching for the mosquito spray or hiring a company, consider that aerosol pesticides don’t kill just mosquitoes. All insecticides used to target adult mosquitoes are nonselective and kill all insects that come in contact with the chemicals. These pesticide sprays also have limited effectiveness. Mosquitoes’ rapid lifecycle (7-10 days from egg to adult) means that mosquitoes outside the reach of the spray repopulate very quickly. A strategy based on spraying (and re-spraying) is not very effective, and it takes a devastating toll on pollinators and other insects.
Dump the water! Mosquitoes are best controlled at the larval stage. Female mosquitoes bite for a blood meal before laying eggs in standing water. The eggs mature to adults in 7-10 days.
- Reduce the population by dumping outside water at least every 7 days – bird baths, potted plant saucers, leaky hoses, toys left outside, kiddie pools, clogged gutters, corrugated drainpipes, upturned lids, pet water bowls. Even a tablespoon of water left for 7 days is enough for mosquitoes to breed.
- Get the kids involved and encourage your neighbors to do the same. The common mosquitoes in our area range from up to 600 yards (Asian tiger) to a half mile to 2 miles (Culex). Concerted efforts across a neighborhood to eliminate standing water will help reduce the mosquito population.
- Where you can’t dump the water, add Bti (Bacillus thuringiensis israelensis, the active ingredient in Mosquito Dunks and Bits), which kills mosquito larvae without harming birds, beneficial insects, or other wildlife.
Set up mosquito larvae traps, either commercial GAT traps or DIY alternatives. These attract females to lay eggs in water containing Bti, which kills the larvae. For a DIY trap, a bucket, water, straw, and a Bti product are all that is needed. 1- and 2-gallon buckets work, if space is too limited for a 5-gallon bucket.
Use mosquito repellents with DEET (25% to 30% – but do not use on infants or cut skin), Picaridin (20%), oil of Eucalyptus, or IR-3535 (ingredient in Avon’s Skin So Soft Bug Guard).
Wear long pants and long-sleeved shirts.
Fix holes in screens.
Use fans on patios or decks – mosquitoes are weak flyers. It doesn’t take much of a breeze to keep them away.
Explore alternatives to dense groundcovers like English ivy, where mosquitoes rest and breed during the day. Native ground covers can offer options.
Mosquitoes become active in spring when temperatures reach 50 degrees F. Keep an eye on the temperatures and be sure to start dumping outside water, setting up mosquito larvae traps, and taking other precautions as mosquitoes become active, usually late April or early May.
For more on strategies to control mosquitoes, check out these resources by the Extension Master Gardeners of Arlington and Alexandria: