Controlling mosquito larvae is highly effective because immature mosquitoes are concentrated in a small area. When the mosquito fully develops, emerges from the water, and takes flight; they can disperse over a large area making control more difficult.
Cass County Vector Control utilizes the best pesticides and practices to eliminate as many mosquitoes as is possible from standing water to eliminate the need for truck or aircraft spraying.
Cass County has over 40 employees that focus on treating standing water full time throughout the summer months. Each vector control employee is licensed to apply pesticides in North Dakota. All products used are registered for residential use by the Environmental Protection Agency. Click the products link for more information, labels, and MSDS.
Mosquito breeding sites in Cass County are documented with GIS technology. Field aides routinely check these sites throughout the season for mosquito larvae or pupae. Treatments are made when necessary. The use of backpacks and all terrain vehicles allow crews to apply thousands of pounds of larvicides to hundreds of acres of breeding sites. Most of the products used are biological, environmentally friendly pesticides which will not harm non-target organisms. CCVC Breeding Site Map
Mosquitoes do have natural predators that will feed on them through all stages of their development. However these predators alone are neither prevalent enough nor physically able to control the vast population of mosquitoes in addition to the other insects that comprise their diet.
A common misconception is that no rain is a good thing as far as mosquitoes go. In some ways this is true, but with regard to ongoing biological control it's not. During a period of drought, the mosquito predator populations dwindle or cease to exist. A lack of rain may mean a lack of adult mosquitoes, but the mosquito eggs are still present awaiting rain (see mosquito biology section). When these rains finally do arrive, natural predator populations that would normally be present must now first repopulate in order to start eliminating mosquito larvae & pupae. This repopulation of predators can be lengthy, giving mosquitoes plenty of time to reproduce several times over.
Some insects that prey on mosquito larvae are: water scorpion, damselfly naiad, dragonfly naiad, mayfly naiad, giant water bug, water beetle, beetle larva, crayfish, freshwater shrimp, tadpole.
Adult mosquitoes have predators including frogs, dragonflies, birds and bats. Research has shows, however, that although mosquitoes do make up part of these creatures' diet, the number or mosquitoes they consume over the course of a night are not significant enough to make a substantial difference in mosquito populations.
This product list is designed to give you an understanding of what employees of Cass County Vector Control use as control materials for larval mosquitoes. This list also contains information to aid you with any questions you may encounter throughout the mosquito season. For information on products to purchase for home use click here.
- Bti granules: Bacillus thuringiensis subspecies israelensis, commonly called Bti, is a microorganism that produces chemicals toxic to insects only when ingested by insects with an alkaline digestive tract. This is a common larviciding agent for control of mosquito. This agent is only effective toward the larvae stage of the mosquito. Bti microbes occur naturally in the environment and were registered in the United States for use as a pesticide in 1961 and reregistered in 1998.
Cass County applicators use Bti to treat large ponds and areas of standing water near pastures, homes, food crops, road ditches, and forestry areas for mosquito larvae. Bti granules are applied at a rate of 10 pounds per acre with a residual effect not exceeding 7 days. BTI easily breaks down in sunlight. This product is readily available to the public at most lawn and garden centers. Bti granules have the signal word "Caution" and displays very low mammalian toxicity.
According the EPA, "...microbial pesticides have undergone extensive testing prior to registration. They are essentially nontoxic to humans, so there are no concerns for human health effects with Bti or B. sphaericus when they are used according to label directions." The US EPA considers Bt's to be practically nontoxic to fish and birds. In fact, under certain use patterns, Bacillus thuringiensis use is considered "organic" by the Organic Materials Review Institute (OMRI) which determines the products that can be used on USDA approved organic farms. Additionally, even groups that are opposed to other pesticides recommend the use of Bti to control mosquitoes.
Bti is the most common pesticide used by Cass County Vector Control as well as a majority of mosquito control agencies throughout the US.
- VectoPrime FG: The active ingredients in VectoPrime FG are Bti and (s)-methoprene. Bti is a biological or a naturally occurring bacterium found in soils. (Bti is short for Bacillus thuringiensis subspecies israelensis.) It contains spores that produce toxins that specifically target and only affect the larvae of the mosquito, blackfly and fungus gnat. EPA has registered five different strains of Bti found in 48 pesticide products that are approved for use in residential, commercial and agricultural settings primarily for control of mosquito larvae. (S)-methoprene is a single-brood insect growth regulator that is most effective against mid to late instar larvae. The combination of two active ingredients provides a wider application window for eliminating mosquitoes in flood water habitats. VectoPrime combines Bti strain with methoprene in each particle. This offers the ability to take advantage of each active ingredient’s strengths.
- Aquabac 200 G: The active ingredient in Aquabac is Bti. Bti has no toxicity to people and is approved for use for pest control in organic farming operations.
- Vectobac G:The active ingredient in Vectobac is Bti.
- Vectolex FG: The active ingredient in Vectolex is Bacillus sphaericus, also a bacteria, and has a very similar mode of action as Bti. Field Aides encounter many drainage systems, storm drains, ditches and collecting pools in Cass County that hold water for extended periods of time. Vectolex is administered by hand at a rate of 5- 20 lbs. per acre, depending on the size of the site, soil type, and specimen collected. Vectolex has a residual up to 28 days if weather permits or no run-off intrudes the site treated.
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Metalarv SPT: MetaLarv S-PT is formulated to release S-Methoprene insect growth regulator for up to 42 days. MetaLarv S-PT prevents the emergence of Aedes, Ochlerotatus, and Psorophora spp., (adult floodwater mosquitoes) and Anopheles, Culex, Culiseta, Coquillettidia, and Mansonia spp.
- Altosid P35: Altosid pellets are applied to sites that require frequent treatments. Altosid pellets containinsect growth regulator (s)-methorprene that are applied to areas of standing water with larval populations. The active ingredient is in mixed with carbon(charcoal) to form a dark, cylindrical pellet, and is dispersed by hand or backpack at a rate of 2.5 lbs of pellets per every acre of water. Under normal conditions a pellet should last for 35 days, however, if there is any flooding or run-off an application can be done more frequently. This product is used as a pretreatment before a rain event, and is applied to known breeding areas every 35 days.
- Altosid XR 150 day Briquettes: Altosid XR Briquettes are released into sites subject to heavy flow of water and are difficult to access on foot. This product contains an insect growth regulator that is used to control larvae populations. The product is in the form of a dark, cylindrical briquette that is dispersed by hand in shallow water (<2 ft. in depth) at a rate of 1 briquette per 100 sq. feet. Under normal conditions a briquette lasts for 150 days. Areas with alternate wetting and drying should not reduce effectiveness. The residual of this product allows Cass County employees to treat some breeding sites only once per season.
