Description: Mosquitoes are among the most serious of insect pests attacking humans and affect the lives of vast numbers of people worldwide. Approximately 3000 different species are found throughout the world of which 150 species occur in the United States. They carry some of the most widespread and devastating human disease agents, including West Nile virus, encephalitis and malaria. Mosquitoes are also responsible for transmitting heartworm in dogs. These diseases, infections and illnesses are now found in just about every part of the United States.
At the time of feeding, the female pierces the skin and injects saliva, which is responsible for the irritation that follows. Blood taken from humans or other animals infected with disease-producing organisms in turn infects the mosquito, which transmits them to future hosts. In the United States, the primary reasons for controlling these pests are to lessen the annoyance caused by their bites and to reduce the transmission of disease.
Life Cycle: The mosquito has four distinct stages in its life cycle: egg, larva, pupa, and adult. A large number of species overwinter as eggs, others as larvae or adults. All have one common requirement – they need stagnant or standing water to complete their life cycle. After a blood meal the female develops her eggs. (Adult males do not bite and feed solely on plant nectar.) One blood meal supplies enough nutrients for her to produce several hundred eggs, which she will lay in or around water. Depending on the species, the eggs are either attached to one another to form a raft or they are laid individually and float on the water. Eggs hatch within days releasing larvae, commonly called “wrigglers,” which feed on microorganisms in the water until they pupate 7-10 days later. Adults emerge 1-4 days later and can live for a period of four to eight weeks. There are several overlapping generations throughout the season. In warmer regions breeding occurs year round.
Typical breeding sites include:
• Standing water
• Irrigation ditches
• Salt marshes
• Roadside ditches
• Snowmelt pools
• Woodland pools
• Catch basins
• Storm water retention areas
Mosquito Control: Unfortunately, there is no easy solution for managing mosquitoes. Countless strategies vary depending on the pest level, water supply, cost, and risk of disease. Many products are available, but nothing is absolutely foolproof. Here are some suggestion:
Habitat Modification: The most effective method for reducing mosquitoes is to eliminate their breeding sites (standing water). The following steps will help:
• Eliminate standing water in rain gutters, old tires, buckets, plastic covers, toys, or any other container where pests can breed.
• Empty and change the water in bird baths, fountains, wading pools, rain barrels, and potted plant trays at least once a week to destroy potential habitats.
• Drain or fill temporary pools of water with dirt.
• Keep swimming pool water treated and circulating.
Reduce Exposure: Mosquitoes are a pervasive outdoor pest. Nonetheless, there are measures that can be taken to minimize the annoyance and incidence of bites.
• Use All Terrain insect repellent and wear protective clothing during mosquito season.
• Make sure that window and door screens are “bug tight.”
• Use head nets, long sleeves and long pants if you venture into areas with high pest populations, such as salt marshes.
• Replace your outdoor lights with yellow “bug” lights which tend to attract fewer insects than ordinary lights.
Larval Control: Immature mosquitoes can be controlled before they develop into biting adults with Bacillus thuringiensis var israelensis (Bt-i). Available under various trade names, it is a naturally occurring, highly specific biological pesticide. Applied to standing water it will kill larvae for up to 30 days. Will not harm people, pets, wildlife or fish.
Adult Control: Mosquitoes rest in protected areas during the day. To reduce high populations of biting adults, spray botanical insecticides on shrubs, the lower limbs of shade trees, under decks, along foundations, and other pest resting sites.
Note: Apply botanical insecticides judiciously. They are not specific to the pest and will have an impact on a variety of beneficial insects, including valuable predators, parasites and honeybees. Most break-down quickly in the environment (within 5-7 days).
Photo Credit: Greater Los Angeles County Vector Control District