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and county-declared pest issues.
MOSQUITO CONTROL
Public Notice:
Map is subject to change
The Natrona County Weed and Pest Control District board has declared the mosquito a pest of local concern. The division’s function is to identify mosquito breeding habitats and implement various control methods.
These methods range from source reduction to the utilization of both biological and chemical control measures. The division is dedicated to working with the public and assisting them with issues related to mosquito control.
Mosquito Fogging activities begin each year around mid-June.
Fogging operations are based on weather and mosquito survey trapping.
The Natrona County Mosquito Control District (NCMC) has the authority and responsibility to perform a variety of mosquito abatement activities geared towards the reduction of disease carrying insects that affect people, wildlife, and livestock/pets. Because insects do not respect boundaries, it is of utmost importance to control them on both public and private lands in Natrona County.
These efforts are funded through property taxes
of Natrona County residents and grants that we can attain for public health.
NCMC performs ground fogging in the evenings starting at sunset and fogging no later than 1:00 a.m. when the mosquitoes are most active and bees and other pollinating insects are not present.
Our goal is to reduce the need for ground fogging throughout the county by using our mosquito larvicide program to control and eliminate mosquitoes in their aquatic habitat before they become a public health threat or nuisance. This involves site reduction, polluted waterway cleanup, and the use of larvicides.
These products used to take care of mosquitoes in larvae stage are excellent. We use a combination of Bacillus thuringiensis subspecies israelensis (B.T.I) and Methoprene, products depending on water type, location, and mosquito species.
Pesticide Labels
Adulticides - Fogging Application:
insecticides specifically formulated to target and kill active, flying adult mosquitoes
PermaSease 4-4
Zenivex E4
Adulticides - Aerial Application:
insecticides specifically formulated to target and kill active, flying adult mosquitoes and administered via aircraft
Anvil 10+10
Duet HD
Pesticide Labels
No Spray Request - Summer 2026
APPLICANTS MUST BE THE LANDOWNER OR AUTHORIZED AGENT
Being placed on the no spray list should be carefully considered – especially due to mosquito-transmitted diseases that are on the move globally, including throughout the U.S.A. such as: West Nile Virus (WNV), Saint Louis Encephalitis Virus, Zika Virus, Chikungunya, and Malaria. For more information visit the Center for Disease Control (CDC) website. NCMC sets approximately 17 traps from May to October throughout the county. Culex mosquitoes are tested in-house for WNV, and/or sent to the public health laboratory in Cheyenne for further testing. Results for these pools are recorded on the Wyoming Department of Health's (WDH) website.
In 2025, 37 out of 241 mosquito pools tested positive for WNV in Natrona County.
If you are requesting a no-spray area, please provide a reason and how you will do your part as a landowner to help control mosquitoes on your property. This could include source reduction, purchasing larvicide/pesticide from Natrona County Weed and Pest (with a cost share), keeping yard clear of debris, cleaning gutter systems, mowing, treating retention ponds, etc. Please click the link below to fill out the No Spray Request Form, or print and return the completed form via email, mail, or in person.
This season we will also offer site visits to advise or help with mosquito related problems within Natrona County including the City of Casper residents, and surrounding cities and towns. Please fill out our google form provided in the link.
For information on where the Culex species are found in Natrona County email
or call NCWP at
(307) 472-5559
For more information and free consultation, please contact:
Natrona County Weed and Pest District, Mosquito Control Division
The mosquito division is located at the Natrona County Weed and Pest office.
Homeowners can take the following steps to prevent mosquito breeding on their own property:
1. Destroy or dispose of tin cans, old tires, buckets, unused plastic swimming pools or other containers that collect and hold water. Do not allow water to accumulate in the saucers of flowerpots, cemetery urns or in pet dishes for more than 2 days.
2. Clean debris from rain gutters and remove any standing water or around structures or on flat roofs. Check around faucets and air conditioner units and repair leaks or eliminate puddles that remain for several days.
3. Change the water in birdbaths and wading pools at least once a week.
4. Fill or drain puddles, ditches and swampy areas and either remove, drain or fill tree holes and stumps with mortar.
5. Eliminate seepage from cisterns, cesspools and septic tanks.
6. Eliminate standing water around animal watering troughs. Flush livestock troughs twice a week.
7. Check for trapped water in plastic or canvas tarps used to cover boats, pools, etc.
8. Irrigate lawns and gardens carefully to prevent water from standing for several days.