Feel a pinch on your ankle? Or a buzzing by your ear? That might be one of the millions of mosquitos that are populating Vermont right now, and while they might be annoying, they can also pose a threat to Vermont wildlife and potentially humans.
Mosquitos can carry multiple viruses and potentially spread them to mammals through bite. The Vermont Agency of Agriculture tests for two viruses that are occasionally found in the state: West Nile virus and eastern equine encephalitis. Both have the potential to be deadly to humans and animals, with EEE being a bigger concern , but also rarer.
Both have been identified in mosquito populations in Vermont this season, with one case of EEE being recorded in a human in Chittenden County in July - the first since 2012. The man was hospitalized for a week and released, although EEE has proven to be deadly in past cases in Vermont.
How many more mosquitos are in Vermont this summer
More cases can be attributed to more mosquitos; so far this season, the population is 94% higher than the historical average - the average number of pests between 2009 and 2023.
However, data may be a bit skewed, said Patti Casey, the Environmental Surveillance Program director for the Vermont Agency of Agriculture, Food & Markets, as the program has grown, and more trap sites have been laid since the program's conception in 2009.
Collecting data on mosquitos means setting traps in all types of locations. The Agency of Agriculture has about 105 trap sites throughout Vermont and have already caught and surveyed 100,000 mosquitos this season. They record their findings in pools, which is a vial of one to 50 mosquitos caught at the same time from the same place. This system is referred to as rapid response surveillance.
How many cases of West Nile virus and EEE have been found in Vermont
So far this season - which will continue to run until the first frost - around late October to early November - 29 pools of mosquitos were found carrying West Nile and 21 pools of EEE. While these numbers are high above the historical average, Casey said it's on par with how many they recorded last year.
Nonetheless, it's a high population. A few factors contributed to this increase, the main being a warmer and wetter season. Mosquitos lay their eggs in wet areas like marshes, which is why many are recorded in the northwestern part of the state near the sprawling watershed of Lake Champlain . Heavy rains last summer and this summer are only added to that wetness, leaving sitting water in more places than ever.
This season was also hotter and more humid than average, something that can speed up mosquitoes' larval development. In those conditions, a mosquito can go from an egg to full-wing development in five to seven days. The department noted that in dryer counties in southern Vermont, the mosquito count was lower.
Mosquito season is growing longer
Casey said what concerns her is that their data is showing the mosquito season to be getting longer due to climate change. EEE is not usually recorded until the tail-end of summer, late-August or September. They started seeing EEE in July this season.
While it's impossible to predict which way the trends will turn in the next few years, especially with the unpredictability of climate changes, Casey said the program is in a good position to stay on top of what's going on to keep the public safe.
"Our program is looking for mosquitos that are positive, but it's kind of like a canary in a coal mine," Casey said. "We hopefully will target the area first before it reaches the mammalian population. Then the health department can start reaching out to people, putting up notices and warning people ahead of time."
How to protect yourself and reduce the mosquito population
Vermont doesn't do statewide mosquito control. Two districts - both in Addison County - established mosquito control programs, but the rest of the state does not have any regular pest management. The state will only intervene when the health department deems that there is an elevated health risk to people.
That plan includes aerial adulticide: spraying insecticides in a mass area to kill mosquitos. This happened in 2013 when human cases of EEE occurred and is something that Casey said is "not taken lightly."
For people who may want to take preventative action, Casey has a few tips.
- Use an EPA-recommended insect repellant.
- Cover up arms and legs if possible.
- Wear a head net if you're working outside.
- Limit outdoor time at dawn and dusk when mosquitos are most prevalent.
- Fix any broken screens or doors to prevent mosquitos from getting inside.
- Dump standing water. This can be any water sitting in buckets, tarps, wheelbarrows, dog bowls or anywhere else.
People are allowed to treat a mosquito population on their property. Casey recommends a biological larvicide that can be added to sitting water and will only harm mosquitos. She also mentioned for any horse owners that don't already know, there is a vaccine to prevent EEE and it should be available through your veterinarian.
Sydney P. Hakes is the Burlington city reporter. Contact her at SHakes@gannett.com .
This article originally appeared on Burlington Free Press: Mosquito population in Vermont at an all-time high. What about West Nile virus, EEE
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