TULSA MASTER GARDENERS - Household Pests (Mosquitoes)

There are over 2500 different species of mosquitoes throughout the world, of which 150 species occur in the United States.¹ Common types of mosquitoes found in Oklahoma are placed in the genera Aedes, Anopheles, Culex, and Psorophora. ²

• Aedes mosquitoes are painful and persistent biters, attacking humans during daylight hours. They do not normally enter homes. Aedes mosquitoes are strong fliers and are known to fly many miles from their breeding sources. Aedes and also Psorophora mosquitoes do not breed in ponds, lakes or extremely stagnant water, so, control efforts during rain periods should be directed at eliminating temporary standing water pools.²
• Culex mosquitoes are painful and persistent biters at dusk and after dark. They prefer to attack domestic and wild birds rather than man, cows, and horses. They will enter homes in search of blood meals. Some Culex species are known to transmit encephalitis (sleeping sickness) to man and horses. The Culex mosquitoes develop in standing or very stagnant water. They cannot survive the wave action of open bodies of water or the movement of water in flowing streams. Culex mosquitoes are often found in containers that hold water, e.g. tanks, troughs, barrels, tin cans, tires, etc.² Culex are generally weak fliers and do not move far from home, although they have been known to fly up to two miles. Culex usually live only a few weeks during the warm summer months. Those females which emerge in late summer search for sheltered areas where they "hibernate" until spring. Warm weather brings them out in search of water on which to lay their eggs.¹
• Culiseta mosquitoes are moderately aggressive biters, attacking in the evening hours or in shade during the day.¹
• Anopheles mosquitoes are the only mosquito which transmits malaria to man.¹

The last decade of the twentieth century saw the introduction of a new more vicious biter in Tulsa County, the Asian tiger mosquito, Aedes albopictus.

The Asian Tiger Mosuito, known as a "Container Breeder" because it deposits its eggs in small collections of contained water rather than the swamps or marshes, is a highly ornamented mosquito that is relatively easy to spot by even the casual observer. The mosquito's color pattern consists of a dark black background that is highlighted with bright white markings. The legs are broadly striped with snow white scales, the thorax has a distinct white racing stripe down its center and the abdomen has incomplete white stripes that appear as lines of bold white dots. Although the name implies formidable size, the Asian Tiger Mosquito is really quite small. A robust adult female in quest of a blood meal measures slightly less than 1/4" in total length. ⁴

The Asian Tiger is a persistent biter that can be a significant pest near its breeding habitat. When the species occurs in large numbers in backyard situations, people can be driven indoors. The mosquito is an opportunistic feeder which will bite as often during broad daylight as it will at dusk. Typical host-seeking behavior involves approaching at ankle level and working its way up the body to find a suitable spot to engorge.⁴

Mosquito Development

The mosquito goes through four separate and distinct stages in its development cycle: Egg, Larva, Pupa, and Adult.

• Eggs: The females of some Aedes species deposit eggs on moist surfaces, such as mud or fallen leaves, that may be near water but dry. When these areas reflood it stimulates the eggs to hatch into larvae.
  The females of the Culex, Culiseta, and Anopheles deposit their eggs directly on the surface of still water sheltered from the wind by grass and weeds, such as ditches, street catch basins, tire tracks, streams that are drying up, and fields or excavations that hold water for some time.³
• Larva: The larva (larvae - plural) live in the water and come to the surface to breathe. They shed (molt) their skin four times, growing larger after each molting. The larvae feed on micro-organisms and organic matter in the water. On the fourth molt the larva changes into a pupa.¹
• Pupa: The pupal stage is a resting, non-feeding stage. This is the time the mosquito turns into an adult. When development is complete, the pupal skin splits and the mosquito emerges as an adult.¹
• Adult: The newly emerged adult rests on the surface of the water for a short time to allow itself to dry and all its body parts to harden. The wings have to spread out and dry properly before it can fly.¹

When adult mosquitoes emerge from the aquatic stages, they mate, and the young adult female seeks a blood meal. The young adult female mosquito taking her first blood meal does not transmit diseases. It is the older female who may have picked up a disease organism in an earlier blood meal that can transmit the disease during a subsequent blood meal.³ Plant nectar is the principle food source for the male.²

Mosquito Control

Large-scale mosquito control cannot be obtained through individual efforts. These controls consist of eliminating breeding areas by drainage, spreading oil films over the surface of the water, using insecticides to destroy the larvae or pupae, or spraying with contact insecticides to kill the adults. Since all of these controls may also destroy habitats, kill fish, birds, or other valuable wildlife, they should be undertaken only after careful study by professionally trained people.

In the Tulsa area contact the Tulsa City-County Health Department at (918) 595-4219 for further information.

Large-scale control is vital for a successful mosquito control program, however, without the cooperation of the individual homeowner it is doomed to failure. The homeowner can use the following techniques to assist in the overall control effort.

• Aquatic Stage Control - Since mosquitoes spend their larval and pupal stages in water, the most effective way to control mosquitoes is to find and eliminate their breeding sites.
  • Backyard Control
    • Remove tin cans, old tires, buckets, plastic sheeting, glass jars, broken toys, and other containers that collect and hold water.
    • Do not allow water to accumulate at the base of flower pots, in pet dishes, wheel barrows, or truck beds for more than 2 days.
    • Change water in bird baths, fountains, and wading pools at least twice a week.
    • Irrigate lawns and gardens carefully to prevent water from standing for several days.
    • Keep grass mowed around ponds and other bodies of water.
    • Clean debris from rain gutters and remove any standing water under or around structures, or on flat roofs.
    • Check around faucets and air conditioner units and repair leaks or puddles that remain for several days.
    • Fill or drain puddles, ditches and swampy areas.
    • Either remove, drain or fill tree holes and stumps with mortar.
    • Eliminate seepage from cisterns, cesspools, and septic tanks.
    • Eliminate standing water around animal watering troughs and culverts.
  • Biological Control
    • Stock ornamental pools with top feeding predacious minnows. Known as mosquito fish, these minnows are about 1 to 1-1/2 inches in length and can be purchased or seined from streams and creeks.
  • Chemical Control
    • Place Bacillus thuringiensis var. isralensis (B.t.i.) in the form of Mosquito Dunks or briquets in standing water that cannot be drained.
• Adult Mosquito Control - Adult mosquitoes can fly long distances, therefore, it is often necessary to supplement larval control on your premises with control measures directed against mosquito adults.
  • Mechanical Barriers
    • Mosquitoes can be kept out of the home by keeping windows, doors and porches tightly screened (16-18 mesh). Those insects that do get into structures can be eliminated with a fly swatter or an aerosol space spray. (See EAH)¹
  • Chemical Controls
    • Repellents are substances that make a mosquito avoid biting people. Several commercially available repellents are effective in preventing mosquito bites.
      • The active ingredient will be listed on the label. The area of skin to be protected should be covered evenly, because mosquitoes will find and bite untreated spots. It is often helpful to use spray repellents on outer clothing as well as the skin. Repellents are formulated and sold as aerosols, creams, solids (sticks) and liquids. You should keep repellents away from eyes, nostrils and lips. Protection generally may be expected up to 6 hours following application.
      • Oil of citronella is another type of mosquito repellent for space repelling. Oil of citronella is the active ingredient in many of the candles, torches, or coils which may be burned to produce a smoke which repels mosquitoes. These are useful outdoors only under windless conditions. Their effectiveness is somewhat less than repellents applied to the body or clothing.
    • Space sprays may be used to kill mosquitoes present at the time of treatment. The major advantage of space treatment is immediate knockdown, quick application, and relatively small amounts of materials required for treatment. Space sprays are most effective indoors. Outdoors, the insecticide particles disperse rapidly and may not kill many mosquitoes. The major disadvantage of space spraying is that it will not manage insects for long periods of time.
      • Mosquitoes can be killed inside the house by using space sprays or aerosols. ² Only insecticides labeled for flying insect management should be sprayed into the air. Best results are obtained if doors and windows are kept closed during spraying and for 5-10 minutes after spraying. Follow directions on the label.
      • Homeowners may use hand-held foggers or fogging attachments on tractors or lawn mowers for temporary outdoor relief from flying mosquitoes. Read the label of the insecticide very carefully. Some products are toxic to fish, birds,and other wildlife. Many may spot car finishes. Read and follow the instructions on the fogging attachments for correct application procedure. Apply the sprays upwind, so the droplets drift through the area where mosquito control is desired. Apply in small amounts periodically, this kills any new mosquitoes that have migrated into the area.
    • Attractants - Mosquitoes are attracted by perspiration, warmth, body odor, carbon dioxide, and light. Several devices are sold that are supposed to attract, trap, and destroy mosquitoes and other flying insects. However, if these devices are attractive to mosquitoes, they probably will attract more mosquitoes into the area and may, therefore, increase rather than decrease mosquito annoyance.³
  • Vegetation Management
    • Adult mosquitoes prefer to rest on weeds and other vegetation.
      • Homeowners can reduce the number of areas where adult mosquitoes can find shelter by cutting down weeds adjacent to the foundation and in their yards, and mowing the lawn regularly.
      • To further reduce adult mosquitoes harboring in vegetation, insecticides may be applied to the lower limbs of shade trees, shrubs and other vegetation. Pay particular attention to shaded areas. Apply the insecticides as coarse sprays onto vegetation, walls and other potential mosquito resting areas using a compressed air sprayer.¹ Do not overapply liquid insecticides, the excess spray drips from the sprayed surfaces to the ground where it is ineffective. These sprays are not effective for more than one or two days.³ Always read and follow label directions before using any pesticide.
  • Insect Electrocutors
    • Numerous devices are available for purchase which claim to attract, repel or kill outdoor infestations of mosquitoes. Most of these devices are ineffective and should be thoroughly researched before being purchased. Insect electocutors (bug zappers) utilizing ultraviolet light as an attractant have been shown to be ineffective in reducing outdoor populations of mosquitoes or their biting activity.¹

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  CAUTION! Pesticides mentioned in this web page are registered for use in Oklahoma, USA!⁵ The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this article.

  ALWAYS READ AND FOLLOW LABEL DIRECTIONS FOR SAFE USE OF ANY PESTICIDE!

   

  Sources:
  1. Mosquito Information, Tom Floore, The American Mosquito Control Association
  2. Oklahoma State University Extension Facts F-7012, Mosquito Control, by Kenneth Pinkston and Russell Wright (Not Available)
  3. New Jersey Agriculture Experiment Station Publication SA220-5M-86, Mosquitoes in Your Life, by Donald J. Sutherland and Wayne J. Crans
  4. Rutgers Cooperative Extension Fact Sheet # FS845, The Asian Tiger Mosquito in New Jersey, Wayne J. Crans
  5. Pesticide Database, Oklahoma Department of Agriculture
  6. A Field Guide to the Insects of America North of Mexico, Borror, Donald J. and White,Richard E., The Peterson Field Guide Series.