Step 1: Larval mosquito control
Mosquito Control employees in Cass County spend the months of April and May applying preventative larvicides (products used to kill mosquito larva) to standing water. In the spring, water temperatures are low,  slowing the insects development.
This provides time to treat the breeding sites and prevent the mosquitoes from becoming adults.

Three products make up the majority of the larvicides used within Cass County.

The first, methoprene, is an insect growth inhibitor that is specific to mosquitoes and insects with similar biology such as midges. Methoprene pellets and briquettes are essential because of their sustained residual. Pellets can control mosquito larvae for 30 days, and briquettes up to 150 days.

Two other products are used in Cass County. Both have a corn cob base coated with one of two naturally occurring soil bacteria (Bacillus sphaericus or Bti). These products disrupt the digestive system of the mosquito, and are not harmful to humans, pets, fish or birds.

Vector Control employees apply corn cob granules to standing water after each rain. The product is quick and effective, but is often used in addition to methoprene pellets because of its run-off capability.

Bti briquettes can be purchased in most lawn and garden departments. Often referred to as “dunks or donuts,” these products can be used by homeowners to kill mosquito larvae in ornamental pools and low–lying areas. Each briquet treats a 100 square foot area for 30 days.

Areas that hold water for more than 5 days could potentially be breeding sites for mosquitoes. Vector Control employees continually map potential breeding areas. This map is available on the larviciding link at

Vector Control appreciates your assistance in locating and treating standing water

Step 2: Adult mosquito control
Adult mosquitoes are often to blame for the shortened barbeque or denied trip to the park. The Red River Valley’s flat terrain, slow drainage, and occasional flooding make the region a perfect breeding ground for the annoying pests.

Three defenses Cass County has against adult mosquitoes are barrier sprays, ULV fogging, and aerial spraying. The first, barrier spraying., uses products with active ingredients such as pyrethrins, permethrin, deltamethrin, and cyfluthrin can be used to mist vegetation that mosquitoes rest in during the day. These products and others can be purchased in most lawn and garden departments, and can provide temporary relief while participating in outdoor activities. Mosquito control professionals use barrier sprays to control mosquitoes around parks, yards, public events in the community.

Ultra low volume fogging is a cost effective way to reduce mosquito populations in our area. With wind speeds between 2 and 10 mph, droplets can travel up to 300 ft from the spray unit.

The amount of active ingredient used to kill mosquitoes is .003 pounds per acre. Most of what is seen coming from the vehicle is mineral oil or water. Because mosquitoes have delicate bodies, not much insecticide is needed to knock them down. Although extensive EPA testing has found that these sprays do not harm birds, pets, or humans, residents are encouraged to take precautions while spraying is conducted. Close the windows of your home and bring pets inside.
Wash fruits and vegetables that may have been exposed to pesticides before eating.

If you are outdoors in the path of the spray truck, the spray operator will stop the sprayer to allow you to get indoors. The operator will turn off the beacon light to indicate that the spray is turned off. If there are several pets or people in the spray path, the operator may pass by and return later in the evening. The sprayer motor will continue to run while the spray is turned off. Spray trucks travel in a north/south or east/west direction based on the direction of the wind. This is for your safety and for the safety of the operator. If all streets and avenues were treated, this would constitute over-treatment and would violate label restrictions.

Spray times and dates are determined according to several factors: trap count information, temperature, and wind speeds. Every effort is made to inform residents of spray schedules. Times and dates are reported by the local media and displayed on this Web site.

After hours, residents of Cass County may call Cass County Vector Control at 298-2382 for announcements.

Aerial applications have become an effective way to supplement larviciding and ground spraying efforts in area communities. Residents are encouraged to take precaution and stay indoors as aerial spraying is conducted. Permethrin products used in aerial spraying are similar to those used in ground spraying. For more information on adult mosquito control products, please access the web addresses listed in this article.

Adult mosquito control products can be harmful to bees and fish. Please contact your local mosquito control program if you wish to be exempt from spraying. If you come in direct contact with control products, wash skin thoroughly with soap and water.


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