Weed and Pest prepares for mosquito season after worst year of West Nile Virus cases since 2013


CHEYENNE – Spring has officially arrived in the Cowboy State and with it, the return of many insects and pests carrying diseases that could impact the health of livestock and Wyomingites alike. Warmer weather accompanied by an increase in standing water due to melting ice and snow has created ideal breeding conditions for mosquitoes across the state. While many species of mosquito can be nothing more than an itchy nuisance, some species, like the Culex tarsalis mosquito, can spread West Nile Virus (WNV), a virus that can be fatal in serious cases. That is why the Wyoming Weed and Pest Council (WWPC) is trying to learn as much as possible about the states mosquito population before adults begin hatching for the year.

Weve been out dipping for mosquito larvae and were finding some pretty significant quantities,” says Brian Songer, Assistant Supervisor for the Sheridan County Weed and Pest District. We bring them back to our office and watch their development daily and try to determine when the adults will start hatching.”

WWPC, along with the Sheridan County Weed and Pest District, have developed a partnership with the City of Sheridan and the towns of Dayton and Ranchester to coordinate mosquito control efforts. The program is a critical measure to prevent the spread of diseases typically transmitted through mosquitoes.

We try to identify the larvae and predict which adult mosquitos are going to emerge.” explains Songer. By doing this, we can predict when well start seeing adults and whether they are a simple nuisance or carry West Nile Virus.”

Wyoming saw a sharp increase in the number of reported WNV cases last year. According to the Wyoming Department of Health, just three human cases of West Nile were reported in 2022. However, 27 human cases occurred in 2023, an average of 4.8 cases per 100,000 people, which far exceeded the national average of 0.7. Four fatalities were also reported, the first WNV-related deaths in Wyoming since 2018.

Humans are not the only ones at risk of catching WNV. Animals, particularly horses, are also at risk of exposure with nearly 50 instances of equine-related WNV cases last year, an alarming increase from just a single case the year prior.

We are very concerned that the trend will continue and thats why weve ramped up our program, trying to get out and predict where the mosquitos are and make our larval treatments more effective,” Songer says.

Following what was considered the worst outbreak of West Nile in 10 years, the Wyoming Weed and Pest Council is advising folks to prepare themselves for mosquito season and is offering tips that can help protect your family and cut down the number of mosquitoes that carry the virus.

• Take time to minimize standing water sources on or near your property. It could be buckets, old tires, or anywhere that puddles form. According to Songer, it could be as small as a water bottle cap or as large as a cattail swamp area.” Also minimize stagnation of irrigation waters by avoiding over-irrigating on saturated soils and by draining pastures of excess water. Ensure irrigation structures are in good working order and remove any blockages in ditches and culverts. Keep water from collecting in low-lying areas
• Protect yourself from exposure to bites. Mosquito-proof or long sleeve clothing can be effective at keeping the bugs at bay, as can treating boots, pants, and socks with EPA-approved repellant. If you are unsure of what repellent to use, the EPA has a useful guide on their website to help you choose.

  • Be sure to protect infants and children by covering their arms and legs. If using repellent, make sure the ingredients are suitable for children and apply using your hands, avoiding eyes, mouths, cuts, and the childs hands. If using sunscreen, apply before spraying repellent.
  • For horse owners, be sure to get your horses vaccinated for WNV in the spring. Ensure the horses are turned in at dusk and dawn which are the times when mosquitos are most active. Fans and sprays are also effective deterrents.
  • Be on the lookout for the symptoms of West Nile Virus. According to the CDC, most people do not experience any symptoms. However, some people may experience a fever, headaches, joint pains, vomiting, diarrhea, or rashes. If you think you or a family member have contracted West Nile Virus, contact your doctor. Contact the WWPC if you or an animal on your property is diagnosed to help guide surveillance and treatment efforts

West Nile Virus has the potential to spread quickly among livestock and among the human population of Wyoming,” said Mikenna Smith, president the Wyoming Mosquito Management Association and member of the Wyoming Weed and Pest Council. The good news is that by taking necessary steps to protect ourselves, the virus can be mitigated before it even starts.”

Mosquitos tend to hatch into full-grown adults mid-to late May and will continue to have a presence through the summer and into fall. You can gain access to more educational resources and how you can keep Wyoming wild and beautiful by visiting the Wyoming Weed and Pest Councils website.

Wyoming Weed and Pest Council (WWPC) is comprised of 23 Weed and Pest Districts in the state of Wyoming. The Council works closely with the Wyoming Department of Agriculture and the University of Wyoming to keep current with the latest technology and research available in the ongoing management of noxious weeds and pests. The overall mission is to provide unified support and leadership for integrated management of noxious weeds and pests to protect economic and ecological resources in the state.