Mosquito-Borne Diseases in Missouri: What Every St. Louis Homeowner Should Know
Most people think of mosquitoes as a summer nuisance, itchy bites that come with backyard barbecues. But in Missouri, mosquitoes carry diseases that can put your family in the hospital. And they become active much earlier than most St. Louis homeowners realize.
If you have kids, pets, or simply enjoy spending time on your patio, understanding the risks — and knowing how to reduce them — is worth a few minutes of your time.
Which Diseases Are Mosquitoes Spreading in Missouri?
Missouri sees several mosquito-borne illnesses each year, and the St. Louis metro area is not exempt.
West Nile Virus
West Nile is the most common mosquito-borne disease in the continental United States. Most people who are infected show no symptoms, but roughly 1 in 5 develop fever, headache, and body aches. In rare cases, it causes severe neurological illness. The CDC's West Nile virus overview notes that people over 60 and those with certain medical conditions are at highest risk for serious complications.
The Missouri Department of Health and Senior Services tracks West Nile cases statewide, and St. Louis County has reported positive mosquito pools in recent seasons.
St. Louis Encephalitis
This disease was literally named for St. Louis after a major outbreak here in 1933. It's caused by a virus transmitted by Culex mosquitoes, the same type that carries West Nile. Symptoms include fever, headache, and in severe cases, inflammation of the brain. While large outbreaks are rare today, the virus still circulates in local mosquito populations.
Eastern Equine Encephalitis
Though less common in Missouri than in eastern states, EEE is one of the most severe mosquito-borne diseases in North America, with a fatality rate of approximately 30% in symptomatic cases. Even a small number of cases warrants awareness.
When Does Mosquito Season Start in St. Louis?
Mosquitoes become active when temperatures consistently reach 50°F, which in the St. Louis metro can happen as early as March. Peak activity runs from May through September, but warm fall days can extend the season into October.
We covered the full seasonal timeline and early-season prevention strategies in our post on getting ahead of mosquito season in St. Louis. The key takeaway: waiting until July to think about mosquitoes means you've already missed months of breeding.
Where Mosquitoes Breed on Your Property
Mosquitoes need standing water to reproduce, and they don't need much — a bottle cap's worth is enough for some species. Common breeding sites around St. Louis homes include clogged gutters, flower pot saucers, birdbaths, kids' toys left in the yard, tarps and grill covers that collect water, and French drain outlets.
Homeowners in areas like Belleville, Edwardsville, and St. Charles County — where larger lots mean more landscaping features and potential water collection points — often deal with heavier mosquito pressure than those in tighter urban lots.
The EPA's Integrated Pest Management principles emphasize that eliminating breeding habitat is the single most effective first step, even before considering chemical treatments.
How Professional Treatments Protect Your Family
Our post on keeping mosquitoes off your outdoor patio covers the DIY basics — citronella, fans, eliminating standing water. But for consistent, season-long protection, professional barrier treatments deliver results that DIY methods can't match.
Pure Pest + Lawn's mosquito service applies monthly barrier treatments from March through October. We target the areas where mosquitoes rest during the day — shaded vegetation, under decks, along fence lines — creating a perimeter that dramatically reduces the population on your property.
How Pure Pest + Lawn Can Help
Schedule a consultation. We assess your property's mosquito risk — standing water, vegetation, shaded rest areas — and identify breeding hot spots.
We apply monthly barrier treatments. Safe, targeted applications from March through October that reduce mosquito populations where they live.
Enjoy your backyard again. Host the cookout. Let the kids play outside after dinner. Stop retreating indoors every evening.
Pure Pest + Lawn has been protecting St. Louis families since 1933 — responsibly eliminating pests while protecting people and pets. Over 1,000 five-star reviews. BBB Torch Award for Ethics.
Don't wait for the first bite. Call 314-222-PEST (7378) or schedule online.
