Mosquitoes in Vermont

Mosquitoes in Vermont

Photo of mosquitoes on top of a pool of water

During the summer months, mosquitoes are regularly monitored at sites around the state for mosquito-borne diseases. Each week, mosquitoes are collected at various locations by the Vermont Agency of Agriculture. These collections of mosquitoes are tested for arborviruses - mosquito-borne viruses - that may affect Vermonters, such as West Nile Virus and Eastern Equine Encephalitis. The Health Department summarizes mosquito testing results and reports of human and animal illnesses every week during the summer and early fall, and compiles data each year in an annual surveillance report.

2021 Surveillance for Viruses Spread by Mosquitoes

Mosquito Surveillance Map

2021 Vermont Mosquito Testing Results

 
What does this graph tell me?
  • Lines represent historic (2002–2020) average percentage of mosquito pools positive for WNV (solid line) and EEE (dotted line).
  • Bars show the percentage of mosquito pools positive in the current year.
  • Historically, the percentage of mosquito pools positive for an arbovirus increases in late August and peaks in mid-September.
 

Mosquito Surveillance Results

Collection week # of Mosquito Pools* Tested # of EEE Positive Pools # of WNV Positive Pools % WNV Positive Pools
Jun 13-19 82 0 0 0
Jun 20-26 104 Not tested Not tested Not tested
Jun 27-Jul 3 159 0 0 0
Jul 4-10 149 0 0 0
Jul 11-17 157 0 0 0
Jul 18-24 148 0 0 0
Jul 25-31 149 0 0 0
Aug 1-7 119 0 0 0
Aug 8-14 154 0 0 0
Aug 15-21 131 0 0 0
Aug 22-28 139 0 0 0
Aug 29-Sep 4 81 0 0 0
Sep 5-Sep 11 86 0 0 0
Year-to-date 1,554 0 0 0

*A mosquito pool is a group of 1-50 mosquitoes of the same species, collected at the same trap location, on the same date.

Animal Surveillance

  • No animal cases of WNV or EEE were reported.

Human Surveillance

  • No human cases of WNV or EEE were reported.

Aedes albopictus Surveillance

  • The Aedes albopictus (Asian tiger) mosquito can carry and transmit Zika, dengue, and other arboviruses. It has an estimated geographic range that includes southern Vermont.
  • Aedes albopictus mosquito eggs were found at one site in Windham County in 2019 among 35 targeted trapping sites in Vermont. 
  • Aedes albopictus mosquito eggs were found at one site in Windham County and one site in Rutland County in 2020 among 18 targeted trapping sites in Vermont.

    Annual Surveillance Reports