Although there are 45 identified species of mosquitoes in Maine, only about half of them are considered
biting pests of humans and even fewer are sufficiently abundant to be considered important pests. Female
mosquitoes feed on blood to acquire the extra protein they need to produce and lay eggs. In this process
they can carry disease organisms and parasites from one animal to another. Eastern Equine Encephalitis and
West Nile Virus are serious human diseases vectored by mosquitoes.
Habitats and life cycles
All mosquitoes breed in standing water. The majority of biting species live in the temporary spring
pools formed by melting snow. Some species live in fresh water swamps, ponds, salt marshes, grassy
ditches, culverts, and natural or artificial containers, such as tree holes, hollow stumps, rock holes, tires,
swimming pools, and cans.
Eggs are deposited by females either individually or in groups on the surface of water or on soil
where flooding will produce pools or ponds. In southern Maine, mosquitoes begin hatching in early to
late March and continue until late April or early May, each species having a particular temperature range
favorable for egg hatch. In central and western Maine, hatching occurs about 2 weeks later. At the
Canadian border, mosquito eggs do not hatch until the last week of April. The larvae are called wrigglers
because of their thrashing motion in the water. They breathe through a straw-like tube held at the
water surface. The length of this life cycle varies by species from 4–30 days.
Adults begin emerging in late April. As long as water is available in their habitats, mosquitoes tend to
gradually increase in abundance throughout the summer. Their numbers generally depend on the amount of
rainfall. During wet summers, mosquitoes will be abundant; in dry summers, numbers will be low and
individuals short-lived. Peak annoyance to humans usually occurs during the month of June. Mosquitoes can spread diseases through their bites, including Eastern Equine Encephalitis (EEE) and West Nile Virus (WNV). The Maine Center for Disease Control has created an informative pages about these and other mosquito-borne diseases. EEE has never been reported in a Maine resident.
Prevention is an important way to manage moquito populations. Elimination of breeding and resting sites are usually beneficial methods.
Eliminate breeding sites
Locate breeding sites before the adults emerge (late April). Drain or remove all stagnant water in
unused buckets, pools, old tires, tin cans, and other discarded containers. Be sure gutters and downspouts
are cleaned. Keep dumpsters and trash receptacles covered to prevent water accumulation. Drill
holes in playground tires, if necessary, to prevent water accumulation.
Eliminate adult resting sites
Cut back or remove dense brush and other vegetation from around buildings. Keep grassy areas
mowed. Manage landscapes to allow air movement to reduce mosquito problems.
Avoid wearing dark colors. Mosquitoes and other biting flies are attracted to dark greens, browns
and black. They are less attracted to light colored clothing, especially whites, and yellows.
Protect natural predators
Predators such as dragonflies provide some natural control of mosquitoes, especially in and around
small ponds and salt marsh pools. However, importing dragonflies is not recommended. Bats and birds,
often cited as important natural controls for mosquito populations. Consider putting up bat and bird houses.
Schools may wish to adopt a policy for use of repellants. Some schools require parents to sign a
consent for school staff to assist younger students in applying repellants provided by parents.
Repellants are pesticides, and although they are exempt from many pesticide regulations, care
should be taken to avoid over-exposure. Insect repellents can repel mosquitoes for 2 or more hours
depending on the ambient temperature, amount of perspiration, exposure to water, abrasive removal, etc.
The CDC recommends the use of repellents containing the EPA registered active ingredients DEET,
Picaradin, oil of lemon eucalyptus PMD), or IR3535. “Pure” oil of lemon eucalyptus (e.g. essential oil) is
not registered and, therefore, not recommended. Oil of lemon eucalyptus should not be used on children
under the age of three years. Concentrations containing 50% or more of any active ingredient do not
significantly increase protection time.
Do not allow children to handle the product. Adults should first apply to own hands and then wipe it
sparingly on the child, avoiding the child’s hands. Apply repellants only to exposed skin and/or clothing (as
directed on the product label). Do not apply to eyes, mouth, cuts, wounds, or irritated skin. When using
sprays, spray first on the hands and then apply to the face, sparingly around ears. After returning indoors,
thoroughly wash treated skin with soap. If use of repellent results in a rash or other bad reaction, immediately
wash the repellent off and contact the local poison control center.
Questionable control methods
“Bug zappers” are commonly sold for mosquito control. Using an electrified grid and an ultraviolet
light, they attract and kill any insect entering the trap. Unfortunately, the lights are not especially
attractive to female mosquitoes who are more attracted to host odor. These devices generally kill more
beneficial insects than pests. Light traps and carbon dioxide traps used by mosquito control programs
are for monitoring purposes and are not effective in reducing mosquito numbers.
There have been several ultrasonic “mosquito repellers” on the market. The sound emitted by these
devices is supposed to confuse mosquitoes and prevent biting. Tests under carefully controlled conditions
have shown that these devices are totally useless for repelling mosquitoes.
There are several chemicals and formulations specialized for mosquito control. Chemical control is only
a temporary solution to mosquito problems. Overuse of chemical pesticides can adversely affect nontarget
organisms and can lead to pesticide resistant mosquito populations that are more difficult to control. However,
if there are extensive mosquito breeding areas on school property, consider having a licensed operator
apply a carefully chosen insecticide to the breeding areas to kill mosquito larvae. This method eliminates
mosquitoes before they disperse and gives more effective, longer lasting control than applications that target
adult mosquitoes. The population should be monitored to determine proper treatment timing. Larviciding
should be used when mosquito egg hatch is complete, but before the larvae transform into pupae. Larvicides will not affect eggs or pupae.
Use the least toxic materials to minimize contamination of aquatic environments and adverse effects to
other organisms in the area. Note that any treatment of the surface waters of Maine requires a special permit
issued by the Department of Environmental Protection.
Insecticide applications that target adults are the most expensive and least effective method of mosquito
control and are not recommended for controlling mosquitoes on school grounds. This method will rapidly
reduce mosquitoes in a local area, but the effect does not last long and applications must be repeated
several times to keep mosquito populations low.
See also: Controlling Mosquitoes on School Properties (ppt)
Anyone making pesticide applications on school property must be
licensed by the Board of Pesticides Control. See “Standards for
Pesticide Applications and Notifications in Schools”.
Printable Version [PDF]
Mosquito-borne Illnesses Health Alert for Maine Schools (8/22/12)
Mosquito Control - A Maine Citizen's Guide
School IPM Action Plan for Mosquitoes (eXtension.org)
Eastern Equine Encephalitis (Maine Center for Disease Control)
Eastern Equine Encephalitis FAQ (Maine Center for Disease Control)
Mosquito-borne Diseases (Maine Center for Disease Control)
Mosquito Youth Education (EEE and West Nile Virus) ( Maine Center for Disease Control)
West Nile Virus (Maine Center for Disease Control)
Jim Occi, Bugwood.org