The Mosquito Problem

Mosquitoes are sometimes carriers of dangerous diseases. In humans, malaria, yellow fever, dengue, and encephalitis, and in dogs heartworm . Most of these diseases, with the exception of human encephalitis and canine heartworm, have been fairly well eliminated from the entire United States. Outbreaks of mosquito borne encephalitis have periodically occured in Missouri. Canine heartworm is an endemic problem, with costs to animal owners escalating each year. Effective mosquito control measures including the elimination of swamp areas, and maintenance efforts to keep road ditches clear and water free have done much to control mosquito populations. This reduces the potential for disease transmission. Each year there remains the possibility that outbreaks may occur since the mosquitoes which have the capability to transmit them are readily found in the state.

Mosquitoes are broadly classified into two groups:
   1) Floodwater mosquitoes;
   2) Permanent water mosquitoes.

Floodwater mosquitoes lay their eggs on damp soil where flooding will occur or, in some cases, above the water line in treeholes, artificial containers, or other small bodies of water. When water (rain) fills these areas and floods the eggs, they hatch, and, after a week or so in the larval stages, broods of mosquitoes emerge simultaneously. These mosquitoes are mainly of the pest variety, and are the first to emerge in the spring months. The eggs are laid in previous seasons and overwinter in that stage. Some of these have only one brood per year, and others emerge continuously throughout the season, with a brood being produced with each significant rain. Eggs of these species have been known to remain viable for up to five years after they were laid. Many of these mosquitoes are strong flyers and may range up to ten miles or more in search of a blood meal. They must have a blood meal to lay eggs.

The permanent water mosquitoes lay their eggs directly on the water surface, either singly or in rafts. Populations of these grow as the season progresses in relation to the availability of breeding habitat, water, favorable weather conditions, and food. Overwintering takes place as adults in protected areas of buildings, caves, etc., or in the larval form, depending on the species. Many of the species in this group do not venture far from their breeding sites.

We have approximately 50 species of mosquitoes in Missouri. Among these, the life span ranges from less than a week to several months. Among all mosquitoes, it is only the female which "bites." She does so in order to obtain the blood meal she requires to lay viable eggs.

How Mosquito Species Multiply
All mosquitoes begin life as eggs. Under proper conditions, the egg hatches in two or three days into a larva, which is aquatic, but must breathe air. The larval stage lasts from four to ten days, depending on species and air temperature. After the larval stage, it becomes a pupa, and the pupal stage lasts another day or two. After this, a winged adult emerges.

Mosquitoes can breed in very small areas of water, including tin cans, old tires, drain troughs, household trash, rain pools and puddles where water can be expected to last for 10 days or longer. Large and deep bodies of water are usually not good mosquito breeding areas because of the presence of natural predators (fish, tadpoles) and the action of waves. Mosquito larvae cannot survive without still water or protection by emergent vegetation.

If you believe you have a mosquito breeding problem on your property, but are not sure, please call the Department of Community Health and the Environment. We will arrange an appointment for an inspection and evaluation, and recommend a possible solution for you.

What You Can Do
You as a resident can do more to control mosquitoes around your home than all other methods combined. Proper maintenance of your property is the first step. All trash and refuse that could contain water should be eliminated. The property should be adequately graded and drained, to prevent any pools or puddles of water that may last 10 days or longer.
You can help your local health department by initiating the following practices on your property:

1. Collect and properly discard all useless artificial containers such as tin cans, bottles, buckets, vases, and old tire casings.
2. Make certain that your rain gutters and downspouts are not blocked by leaves or other debris which would cause water to stand in them.
3. Stack pails, barrels, tubs, vases up-side down.
4. Cover boats and canoes, or store them upside down.
5. Stock rock gardens, garden pools and lily ponds with small fish, including the top water feeding minnow and gold-fish.
6. Fill in or drain any low places where water may stand for more than a week.
7. Empty and clean small wading pools at least once each week.
8. Provide proper maintenance of back-yard swimming pools to discourage the development of mosquitoes.
9. Drain livestock water tanks once each week or stock them with goldfish or top water feeding minnows.
10. Cover rain barrels, cisterns or fire barrels with 16-mesh wire screening.
11. Install splash blocks around homes to carry water away from foundations.
12. Store wheelbarrows upside down.

After you have done all you can do to reduce the number of mosquitoes on your property, you can protect yourself against the ones that remain by being sure your home is adequately screened, by wearing protective clothing, and by using mosquito repellent, which is quite effective.

Mosquito Links

• American Mosquito Control Association
  
• A Synopsis of the Mosquitos of Missouri and Their Importance From A Health Perspective - Handbook
  Download Handbook As A Microsoft Word Document
  Download Handbook As An Adobe Acrobat Document

If you have any questions or concerns regarding controlling mosquitos please contact us.

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