Choosing the best mosquito spray often depends on the application for which that spray will be used. An insecticide, for example, is much different than an insect repellent. One type of spray is met only to ward off mosquitoes. The other is used to kill the mosquitoes.
The best mosquito spray, as far as a repellent goes, is one that contains DEET, according to most health officials. It has been recommended by the United States Centers for Disease Control along with many other medical associations. When used as directed, it is considered to be a very safe product, even for children.
DEET works by not allowing mosquitoes and other biting insects to zero in on a source of carbon dioxide, which is how they often find their victims. Those who choose a concentration of DEET in their mosquito spray will be protected for a certain period of time. Some studies suggest that using 100 percent DEET as directed will provide as many as 10 hours of protection. There is a proportional relationship between the amount of DEET in a product and the length of protection.
In general, for personal protection, using mosquito spray that contains DEET is recommended over using sprays meant to kill. While repellents will not control the mosquito population, they will prevent many bites. For those who want to take a more proactive approach, there are a number of products designed to kill mosquitoes as well.
While not a true mosquito spray in some cases, a larvicide can be sprayed or spread on a body of water to prevent mosquitoes. One of the most common chemicals used in larvicide is Methoprene, a chemical that will kill mosquito larvae but will not harm other aquatic life. This selective killing feature makes it very useful in applications such as backyard fish ponds and farm ponds. Further, killing the mosquitoes before they reach adulthood is also a good way to control future populations and is the most effective way to kill existing populations.
Another type of mosquito spray often applied is through the use of a fogger. Foggers use a variety of insecticides, though their ability to control populations of mosquitoes is generally limited. At most, they may provide a few hours of protection if conditions, such as a lack of wind, are right. Cities often use foggers for large-scale mosquito spray applications, but this material is used over a larger geographic area than home sprayers, maximizing its effectiveness.