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Mosquito Biology

Mosquitoes are members of the insect order Diptera, meaning two wings. Mosquitoes undergo complete metamorphosis.This means they have a life cycle that includes four stages of growth: eggs, larva, pupa, and adult. Depending on the species, mosquitoes can occupy a variety of habitats such as woodland pools, brackish marshes, or artificial containers.

Stage 1: Eggs

Only female mosquitoes have the ability to lay eggs. In order to develop eggs, the female needs a blood meal. With each blood meal, the female can lay several hundred eggs. The eggs are laid in or around water and will attach to one another, forming a raft. Individual eggs will float independently. After 24 to 48 hours, the eggs will hatch and release larvae.

Stage 2: Larva

The larva stage takes approximately seven days to complete depending on food and temperature conditions. The larvae require water to live. If the water source dries, the larvae will die. The larvae grow and feed during four growth periods called instars.Larvae are sometimes referred to as wigglers due to the jerky motion made while swimming.

Stage 3: Pupa

Seven to ten days after the eggs hatch, the larvae transform to pupa. At this time, they can breathe oxygen. However, they cannot feed (bite). Mosquitoes spend one to two days  in the pupa stage. They will then emerge from the water as an adult mosquito.

Stage 4: Adult

  • The males emerge first and hover around the site waiting to mate with the females.
  • Male mosquitoes do not bite; only females do.
  • The blood a female mosquito acquires through its bite is not a source of food, but a source of protein for egg production.
  • Male mosquitoes live for about two weeks, while females live from three weeks to several months.  Female mosquitoes can lay approximately 500 eggs during their life span.
  • The female in some species may bite up to 10 times to get a single blood meal.

Mosquito Viruses

Mosquitoes are capable of spreading a number of viruses called arboviruses or arthropod-borne viruses. The two most common arboviruses in eastern North Carolina are Eastern Equine Encephalitis (EEE) and West Nile Virus (WNV). Both of these viruses involve a complicated transmission cycle between mosquitoes and birds. Certain mosquitoes can acquire the virus from an infected bird and potentially infect horses and humans. The transmission cycle of EEE and WNV are shown below. For detailed information on these viruses click on the Fact Sheet links given.

EEE Fact Sheet External link - Pitt County is not responsible for content on external sites

WNV Information External link - Pitt County is not responsible for content on external sites

EEE Transmission Cycle

West Nile Virus Transmission Cycle

Source cdc.gov

Source cdc.gov

EEE transmision cycle

WNV transmission cycle

Click here for detailed pictures and illustrations of the mosquito’s life cycle and habitat External link - Pitt County is not responsible for content on external sites

Protective Measures

Protection from mosquito bites requires responsible decisions on the part of every citizen. The following guidelines should be followed to reduce the risk of mosquito bites.

  • Avoid outdoor activity in areas with high mosquito infestation.
  • Avoid outdoor activity at dusk and dawn when mosquitoes are most active.
  • Cover exposed areas with long pants, long-sleeve shirts and hats.
  • Use mosquito repellants containing DEET. Click here for information on what DEET is and the potential risks associated with it. External link - Pitt County is not responsible for content on external sites
  • Always follow label directions and be especially careful when applying to children. Click here for important guidelines on DEET use. External link - Pitt County is not responsible for content on external sites
  • The very young, elderly, and persons with lowered immune systems have the highest risk for acquiring disease from mosquito bites. These individuals should use extra precaution.
  • Keep all window and door screens in good repair so mosquitoes cannot get indoors.

Protecting Your Horses

While there currently are no vaccines available to protect humans from mosquito borne viruses, there are vaccines available to protect horses. These vaccines are available for both EEE (Eastern Equine Encephalitis) and WNV (West Nile Virus). It is recommended that horses be vaccinated annually. Check with your veterinarian on the proper procedure for getting them vaccinated.

horse

Click here for additional information about mosquito diseases in horses and how you can prevent them External link - Pitt County is not responsible for content on external sites

Control Measures

A variety of control measures are available to reduce mosquito populations including education, source reduction, larvaciding, and adulticiding. Surveillance techniques are in place to determine the optimum time to implement these control measures.

  • Source Reduction

If requested, mosquito control personnel are available to perform site evaluations.
Many of these requests are handled by simply eliminating the source of the problem, which often are a result of the Asian Tiger Mosquito.  The only way to controlthis mosquito is to eliminate its breeding source. Education is a key component of this. Click here for more information on the Asian Tiger Mosquito. External link - Pitt County is not responsible for content on external sites

  • Larvaciding

    Larvaciding is the use of biological agents to kill mosquito larvae.  Mosquito breeding sites are found through active larval mosquito surveillance. These sites are mapped and monitored for breeding mosquitoes.
  • Adulticiding

    Adulticiding is the use of Ultra Low Volume (ULV) spraying to kill adult mosquitoes.  This is the least effective control measure for reducing the mosquito population within an area.  One way staff determine that an area has a particularly high number of adult mosquitoes is to conduct physical landing counts.  Landing counts are simply the number of mosquitoes that land on a person within a specified amount of time.  When it is determined that this number is significant enough to warrant adulticiding, staff place CDC light traps in an area to catch adult mosquitoes. The collected mosquitoes are identified by sex and species. This data, along with physical landing counts, determine the need for spraying.

Click here for more information on Pesticides and Mosquito Control  External link - Pitt County is not responsible for content on external sites

Control Products Used By Pitt County Mosquito Control

Product

Active Ingredient

Type of Control

Product Info

Altosid (30Day Briquette)

Methoprene

Larvacide

Label

MSDS

Altosid XR (150 Day Briquette)

Methoprene

Larvacide

Label

MSDS

Vectolex CG

Bacillus sphaericus

Larvacide

Label

MSDS

Vectolex WDG

Bacillus sphaericus

Larvacide

Label

MSDS

Summit BTI Briquette

Bacillus thuringiensis subsp. Israelensis

Larvacide

Label

MSDS

Agnique MMF

Ethoxylated alcohol

Larvacide

Label

MSDS

Biomist 3+15

Permethrin

Adulticide

Label

MSDS

Flit

Permethrin

Adulticide

Label

MSDS

What you can do...

Mosquito control begins with you. The majority of mosquito problems are within 100 to 200 yards of where they are breeding. Mosquitoes need standing water to breed, so the best way to reduce the mosquito population is to eliminate or reduce the sources for standing water. 

  • Replace birdbath water at least twice a week.
  • Make sure street drains are covered and clear of debris so that water drains well. 
  • Fill low lying areas within your yard with dirt or sand. 
  • Clean rain gutters so water can flow freely.
  • Cut grass frequently.  Areas of tall grass can become a breeding site for mosquitoes.
  • If you have ornamental ponds, tree holes or other low water holding areas that you cannot fill, contact Pitt County's Mosquito Control Program for assistance.
  • Make sure that pool pumps are working properly to ensure that pool water is adequately circulating. 
  • Store plastic wading pools inside or turn them upside down when not being used.
  • Store children’s toys that have the potential to collect water inside or turn items upside down if left outside.
  • Remove and discard old tires and drill drainage holes in tires used for playground equipment.
  • Do not leave trash can lids upside down and look for water standing in the bottom of trash cans.
  • Turn wheelbarrows upside down when stored outside.
  • Repair dripping outside faucets.
  • Remove or turn over clay pots and plastic containers.
  • Remove unused pet food and water dishes.
  • Flush water in the bottom of plant holders at least twice a week.
  • Clean and discard any yard trash or debris.
  • Check tarps such as those for boats, pools and fire wood for areas holding water and arrange them so water will drain.
  • Pump out bilges in boats. Store canoes and small boats upside down.
  • Inspect construction sites and do-it-yourself projects to ensure there is proper drainage.
  • Keep ditches free of debris so they can properly drain.
  • Cover or screen rain barrels.
  • Flush livestock troughs at least twice per week.

house

Source: Ontario Ministry of Health and Long-Term Care

Mosquito Facts

  • Most mosquito problems start in your local environment.
  • Mosquitoes are not capable of spreading AIDS. Because HIV does not multiply nor survive in the mosquito, it will not ‘leak’ into any of the body fluids and will only stay in the blood meal and in the digestive channel of the mosquito. Hence, HIV cannot be transmitted though mosquito bites from one person to the next, even if a mosquito bites a person with HIV infection.
  • People are not always the primary blood hosts for mosquitoes. Many mosquitoes prefer to seek blood from birds and other mammals. The Arctic Circle has very few people, but millions of mosquitoes.
  • Most mosquitoes do not like to travel and will stay within a 1 mile radius of their breeding site, however salt marsh species are capable of flying up to 40 miles.
  • Mosquitoes locate their blood hosts through scent, sight, and heat. They can detect our scent, especially the carbon dioxide we are exhaling, from up to 100 feet (30 meters) away. They can see you at a distance of about 30 feet (10 meters).
  • Bug zappers kill very few mosquitoes, but kill numerous beneficial insects.
  • There are over 3,000 mosquito species worldwide. Sixty (60) of these species are in North Carolina and 25 species are in eastern North Carolina.
  • Mosquitoes are responsible for more deaths throughout the world than any other living creature.
  • Studies have shown that while bats and birds consume a large number of insects, mosquitoes are a very small proportion of their diet.
  • The itch of a mosquito bite is due to chemicals it injects to keep the blood from clotting.

mosquito

Information Sources

Centers for Disease Control and Prevention, www.cdc.gov/ncidod/dvbid/arbor/ External link - Pitt County is not responsible for content on external sites

National Pesticide Information Center, http://npic.orst.edu External link - Pitt County is not responsible for content on external sites

NC Division of Public HealthExternal link - Pitt County is not responsible for content on external sites

USDA, Animal and Plant Health Inspection Service, Veterinary Services

US Environmental Protection Agency, www.epa.gov/pesticides/health/mosquitoes/ External link - Pitt County is not responsible for content on external sites

Other Mosquito Information Links

North Carolina Mosquito and Vector Control Association External link - Pitt County is not responsible for content on external sites
American Mosquito Control Association External link - Pitt County is not responsible for content on external sites
Mosquitoes and DEET External link - Pitt County is not responsible for content on external sites
Heartworm Disease In Dogs and Cats External link - Pitt County is not responsible for content on external sites

Contact Us

Do you have a mosquito question or concern? Contact the Pitt County Mosquito Management Program. We are available to help with your problem and provide educational assistance.

Vector Control Manager
Phone: (252) 902-3210
Fax: (252) 830-4974