Larvicides

Larviciding involves applying materials to breeding habitats in order to kill mosquito larvae and pupae. This method is considered to be the most effective method of mosquito control after source reduction. If an area cannot be altered or manipulated to drain standing water within one week, a chemical method of control may be necessary.

The type of larviciding material you use should be based on the type of mosquito (permanent water or floodwater), the larval or pupal stage of the mosquito, environmental conditions of the site, cost of materials and labor requirements to make the application. Some of the most popular larvicides are: BTI’s, Monomolecular Films, Larvicide Oils and Growth Regulators. These products differ in the way they affect the mosquito and the stages of development they impact. Below is a description of each product.

BTI’s - The active ingredient in BTI products Bacillus thuringiensis israelensis, is a naturally occurring soil bacterium. This clay-like protein works as a stomach poison and ruptures the gut of the mosquito larva. One disadvantage is that because these products must be ingested, they have to be applied while the larvae are in the first three instars. BTI’s work best in unpolluted, temporary waters with limited organic matter. They can also be used in highly organic or polluted water but will need to be applied at higher rates. According to the EPA, it is essentially nontoxic to humans and does not pose risks to wildlife or the environment when used according to label directions. Two of the most popular BTI products are BTI Briquets and BTI Granules.

BTI Briquets are “donuts” that float on the water’s surface where immature mosquitoes reside. They are often applied to areas difficult to access and can be broken up for use in small areas. In large areas, it is important to ensure that these products remain where they are placed. They can be anchored down with string, slipped over a dowel rod, or other means. They should last approximately 30 days.

BTI Granules are good for short-term treatment for accessible areas and are perhaps the most widely used larviciding product available. A disadvantage of this product is that it is somewhat labor intensive as you must continually monitor and retreat areas as necessary, every 7 to 14 days.

Mono-Molecular Surface Films (MMF) - This unique formulation breaks the surface tension of water, which allows it to be effective on all stages of mosquitoes. Because MMF kills mosquitoes by a physical action, there is no need to worry about the type of mosquito species or if the mosquitoes will become resistant. Another favorable feature of MMF’s is that applications may only need to be made every 2-3 weeks because of its long lasting physical action. The product itself is invisible but its’ presence can be detected by applying a drop of oil onto the treated surface. This product works great in clean or polluted waters. However, the presence of aquatic plants or surface debris may increase the amount of product needed. The only time it is not effective is when there is a “draw” of surface water, which removes this surface film. 

Mosquito Larvicide Oil - This product, composed of mineral oil and a dispersing agent, is similar to diesel fuel. The dispersing agent enables the oil to spread for thinner coverage, yet it will leave a visible “sheen” on the water’s surface. It can be applied anytime prior to adult emergence. Once applied, it will suffocate larvae and pupae. It is effective regardless of the amount of organic materials in the water. However, if misapplied, it may be toxic to fish and other aquatic organisms.

Growth Regulators - These products, if applied prior to the pupal stage, should prevent adult emergence. The active ingredient is an insect growth regulator that mimics a natural juvenile hormone. When present in the larval habitat, it keeps immature insects from maturing into adults. Unable to transform, the mosquito dies in the pupal stage. Briquets are the most common form of this type of product but granules and liquids are also available.

MUG-A-BUG  -  254 South U.S. Route 51  -  Forsyth, IL 62535

Phone (217) 875-3303  -  Fax (217) 875-5054  -  info@mugabugmosquito.com

Site Last Updated: 9/1/2009