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Credit: Photos: MMCD

Catch-basin maps help St. Paul's Metropolitan Mosquito Control District organize and monitor mosquito breeding sites.
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A Metropolitan Mosquito Control District employee tracks levels of mosquito larvae in natural wetland.
A mosquito primer

Adulticides kill adult mosquitoes and can be used in tandem with larvicides. They are necessary when adult mosquitoes migrate into an area, or when an outbreak of disease poses a health threat to a community. Adulticides kill only those mosquitoes in the area at the time of application; repeat applications may be necessary.

Culex mosquitoes, which breed in stagnant water high in organic matter, are the most common source of West Nile virus, encephalitis, and other diseases.

Floodwater mosquitoes lay their eggs on moist soil. The eggs hatch after the soil is flooded but can remain dormant in dry soil for months.

Larvicides kill mosquitoes before they can develop into biting, breeding adults. They usually are target-specific, easy on the environment, effective, efficient, and economical.

Larvae (also known as wrigglers or wigglers) undergo four molts as they develop into pupae. Development may take as little as four days, depending on temperatures and conditions.

Permanent-water mosquitoes lay their eggs on water surfaces in marshes, ponds, catch basins, open containers, and tree holes. The eggs usually hatch in one to three days.

Pupae (or tumblers) rest on the surface of standing water, where they mature into adults unless killed with a larvicide during their larvae stage.