Pest Information
Mosquitoes
Mosquitoes
Culicidae
Description
Adult mosquitoes are small, usually about 1/4 inch long, slender-bodied
biting flies. Their wings are long, slender, and hairy, particularly along
the veins. Some mosquitoes, such as Psorophora, are larger, about 1/2 inch
long. Adults lay elongate eggs that are about 1/40 inch long, and dark-brown
or black when ready to hatch. The eggs are laid in batches of 50 to 200,
either separately or glued together in small clusters. Eggs hatch into elongate,
legless, larvae with a large head with mouth brushes and a short tube (siphon)
at the posterior end. Fully grown larvae are usually 1/4 to 3/8 inch long
depending on the species. They change into pupae that are comma-shaped.
Life History
Depending on the species, mosquitoes may overwinter as eggs, fertilized
adult females, or larvae. Adult males feed on flower nectar. Only adult
female mosquitoes bite and feed on blood which is used to produce eggs.
The eggs are laid near or in water and hatch into larvae that live in water,
usually at or near the surface. Most larvae feed on bits of suspended organic
debris, using their mouth brushes to strain the food out of the water. The
larvae quickly wiggle to the bottom when disturbed, and thus are commonly
called wrigglers.
Larvae live for about a week and then change into pupae which also live
at or near the water surface. Pupae do not feed but are active, diving end
over end to the bottom if disturbed, and are therefore, called tumblers.
After a 2 or 3 day pupal stage, adult mosquitoes emerge onto the water surface.
Adults are light enough to stand on the surface film. Once they have dried
and hardened from their emergence, they fly to grass, shrubbery, or other
foliage. Mating occurs within the next day or two and then females start
to search for blood meals. Associated with their egg-laying habits, species
tend be either floodwater or container-breeding mosquitoes.
Container-breeding Mosquitoes
These mosquitoes lay their eggs in stagnant water in treeholes, old tires,
clogged gutters, old tin cans, and anything else that will hold water. The
presence of organic matter such as fallen leaves and grass clippings make
the water even more attractive for egg-laying. Eggs are laid on or just
above the water surface. The eggs will usually hatch within 2 or 3 days
after they are laid.
Control
Reduce the number of mosquito breeding sites outdoors by eliminating containers
that will hold water such as old tires and tin cans. Keep eave troughs clean
of fallen leaves and other debris so that rainwater drains readily. Empty
and clean bird baths, pet watering bowls, and children's wading pools weekly.
Abandoned swimming pools should be kept covered to prevent rainwater accumulation.
Backyard lily ponds and other areas that hold water throughout the summer
can be stocked with fish from a local bait shop to eliminate mosquito larvae.
Most ponds and lakes are not a major source of mosquitoes because resident
fish populations eat the larvae.
Keep screens on windows and doors in good repair.
Avoid going outdoors at or shortly after dark or into forested and other
areas where mosquitoes are numerous during floodwater mosquito outbreaks
or encephalitis warnings. Mosquitoes are attracted to persons who are wearing
dark clothing and perspiring. Some individuals are inherently more attractive
to mosquitoes than others, apparently related to chemical constituents of
the blood and vapors given off through the skin.
Use a repellent when entering mosquito-infested areas. There are several
commercially-available repellents that may be used on clothing or exposed
skin to provide protection.
Spraying grass, shrubs, and other vegetation with an insecticide can reduce
mosquitoes for a few hours to a couple of days. This may be useful prior
to wedding receptions, parties, or other occasional evening outdoor events.
There are some popularly touted mosquito control methods that are not very
effective. Bug zappers are not effective in controlling biting mosquitoes.
Their light will actually attract biting mosquitoes, but then they search
for a blood meal rather than fly into the trap. Various birds and bats will
eat large numbers of mosquitoes when they are very numerous, but will tend
to ignore them when few in number, preferring larger insects such as moths.
Some plants have mosquito repelling properties, but are effective for only
a small area around them.
Community wide mosquito control programs can be quite effective if they
are conducted as an integrated pest management (IPM) program. This includes
monitoring and draining or treating mosquito breeding habitat such as occasionally
flooded marshes, river backwater areas, swamps, and other low-lying areas,
controlling larval populations with insecticides and biological control
agents, and occasional fogging of adult mosquito outbreaks based on light
trap collections or mosquito landing counts.
