The most effective way to kill mosquitoes

Author: Kyle Moppert, state entomologist

Are you guilty of saying, “those pesky mosquitos are making me sick!” If you are, then according to the World Health Organization, you’re 100 percent correct. Mosquito-borne diseases more than 300 million clinical cases each year are attributable to mosquito-borne illnesses, and despite great strides over the last 50 years, those illnesses continue to pose risks in the United States.

West Nile virus and St. Louis Encephalitis virus, both from the same family of viruses called flaviviruses which cause similar diseases, are found in Louisiana.

Humans contract West Nile when they are bitten by mosquitos infected with the virus. When people are infected with West Nile, the virus might affect them one of three ways. West Nile neuroinvasive disease is the most serious type, infecting the brain and spinal cord. Neuroinvasive disease can lead to death, paralysis and brain damage. The milder viral infection is West Nile fever, in which people experience flu-like symptoms. Most people who are infected will not experience symptoms, and not know they’ve contracted the disease.

Modern mosquito control programs are multifaceted and include surveillance, source reduction, and a variety of larval (just hatched mosquitos) and adult mosquito control strategies. 

Monitoring for Virus-Carrying Mosquitoes

Mosquito surveillance is an essential component of a mosquito-borne disease prevention and control program. The objective of surveillance is to determine which mosquito species are active, where they are located in a geographic area, seasonal occurrences and abundance of carriers of mosquito-borne pathogens.

Up-to-date information on mosquito species, their distribution and abundance of virus-carrying mosquitoes is essential to developing effective prevention and control programs. Samples of adult female mosquitoes can be collected and grouped by species and tested for the presence of mosquito-borne viruses. Surveillance data is then used to plan insecticide applications when and where mosquitoes are abundant.

Effective Mosquito Control

Control efforts can begin once established mosquito threshold populations are exceeded or virus-laden mosquitoes are found. 

Source reduction involves eliminating or modifying the habitat that mosquitoes need for reproduction. This includes proper management of water in the environment to reduce the production and survival of the mosquitoes. Biological control, such as the use of fish to reduce larva, are utilized to aid in control mosquito populations.

The Louisiana Department of Health’s mosquito surveillance program includes human surveillance and documents all reported human cases that occur in the state each year in its Arbovirus Surveillance Summary.

The Department also monitors mosquito-borne illnesses such as chikungunya, dengue and Zika, and includes any reported cases also reported in the Arbovirus Surveillance Summary. All of the state’s reported cases of those illness have been associated with travel to areas with active transmissions.

Protecting yourself against mosquito-borne illnesses is the first line of defense against these viruses and diseases.

• If you will be outside, you should wear a mosquito repellent containing DEET. The American Academy of Pediatrics (AAP) recommends that repellents should contain no more than 30 percent DEET when used on children. Insect repellents also are not recommended for children younger than 2 months of age. CDC recommends that you always follow the recommendations appearing on the product label when using repellent.
• Apply repellent on exposed skin and clothing. Do not apply under your clothes or on broken skin.
• To apply repellent to your face, spray on your hands and then rub on your face, avoiding your eyes.
• Adults should always apply repellent to children.
• Wear long-sleeved shirts and pants when outdoors for long periods of time.
• Avoid perfumes and colognes when outdoors for extended periods of time.
• Make sure that your house has tight-fitting windows and doors, and that all screens are free of holes.

In addition, you can also take steps around your home to limit where mosquitoes can breed and the opportunity for them to enter your home.

• Reduce the mosquito population by eliminating standing water around your home, which is where mosquitoes breed.
• Dispose of tin cans, ceramic pots and other unnecessary containers that have accumulated on your property. Turn over wheelbarrows, plastic wading pools, buckets, trash cans, children's toys or anything that could collect water.
• Drill holes in the bottom of outdoor recycling containers. Drainage holes that are located on the container sides collect enough water for mosquitoes to breed.
• Check and clean roof gutters routinely. They are often overlooked, but can produce millions of mosquitoes each season.
• Aerate ornamental pools or stock them with fish. Water gardens can become major mosquito producers if they are allowed to stagnate.
• Clean and chlorinate swimming pools that are not being used. A swimming pool that is left untended by a family for a month can produce enough mosquitoes to result in neighborhood-wide complaints. Be aware that mosquitoes may even breed in the water that collects on swimming pool covers.  

For more information about LDH’s effort to prevent mosquito-borne illnesses, visit http://www.ldh.louisiana.gov/index.cfm/page/1930.