Mosquitos are a common pest worldwide from the steppes of Siberia to the tropical Amazon. Australia has plenty of representatives, well over 250 named species throughout. Whilst their annoying 'biting' habits are what we notice most, mosquitos are probably a greater agent of death and illness than the worlds stockpile of nuclear weapons. Millions of these miniature dirty syringes flit from person to person and animal to person cross infecting with worms, protozoa and viruses. Dozens of illnesses effecting animals and people include malaria, dengue & Ross River fever, myxomatosis and dog heartworm.

Whilst the habits and dangers from mosquitoes vary from species to species and area to area there are some things most have in common.

• They lay their eggs in or near water.
• Only the females take a blood meal. The males get by on plant nectar.
• The adults fly.
• They are very annoying.

Smart Weapon

It is known that mosquitos use a number of sensors to locate their victim, (usually a mammal,) for a blood meal. Initially it is wind that dominates the direction of their search. Once within about 30 metres the female mosquito may pick up the changing levels of carbon dioxide from the breath of the potential target. They are incredibly sensitive to these minute variations and will search inexorably down the stream. Odours may then come into play to assist the search and bingo, they are buzzing at your ear. Finally they use their super infra-red detector to select the target area. This is why many are most often bitten on the feet, hands and head. Here the blood vessels are closest to the surface and that nice warm blood presents a beautiful infra-red picture to our buzzing friend who alights, ever so gently to extract just a tiny amount of blood you can certainly spare, for the benefit of her children. The health risk arises because she also must inject substances before drawing blood to stop it clogging the fine syringe. The result is a direct serum blood transfer containing God knows what. Whilst the western world is obsessed with bio-weapons in the mail and scattered from aeroplanes, just think of the economic power of this natural delivery system.

Economic Importance

The worldwide economic impact of mosquitos is enormous. Around 6% of the world population will die of a mosquito borne disease and many times more will suffer debilitating illnesses. It would be a mistake to think that this only effects third world countries. Malaria, endemic centuries ago in Europe, is making a comeback. Always a difficult ailment to deal with, we have seen the emergence of new hardier and more aggressive strains. The appearance of West Nile virus in New York State initiated a multi million $US control campaign. The potentially lethal Japanese encephalitis is in Australia along with Murray Valley encephalitis, dengue and Ross River viruses. We have occasional cases of malaria but we have the potential carriers and virulent strains are right on our northern doorstep. Many employers with staff at risk use extensive mosquito management services. Lost time and productivity as a result of mosquito borne illnesses has significant economic impact for many mining and other large commercial enterprises. Many parts of the tourist industry suffer not only from staff down time but also lost income due to mosquito attacks on their clients

Cultural Control

Because mosquitos are mobile and scattered as adults and relatively stationary and concentrated at the egg, larval and pupa stage it is obvious where they can be most effectively controlled. Removing an available breeding site will be hundreds of times more effective than killing a hundred mosquitoes. Old tyres, clogged gutters and drains, open water containers, trays under pot plants are all breeding sites the home owner can do something about. Chuck it, cover it, clean it, fix it are all things you can do. Of course some mosquitos can travel enormous distances (such as the salt-marsh mosquito) and this strategy won't work for them but for others like the dengue mosquito that are poor fliers, you can be pretty sure the buzz in your ear is home grown or compliments of your neighbour. Treatment of larger areas such as dams, swamps and creeks should be left to professionals.

Other Options

Limited control of adults can be achieved and by far the most effective is screening. Adults are attracted to ultra violet light at a limited range and light traps are often used for monitoring programs. There are more sophisticated and efficient devices that combine UV light with other attractants that can catch significant numbers that may have some effect on breeding levels. These mainly act as the primary attractant near the area you want to protect thereby reducing biting in that area. For best results using these types of systems, you should have a professional assess the site and the problem. Residual surface sprays can reduce resting areas and aerosols can have a good "knock-down" effect in enclosed environments.

The Environment

Apart from the good old can of fly spray, untrained people should avoid resorting to chemical control, particularly outside. A carefully considered balance must be struck between the efficacy of the treatment and the environmental impact. Detailed knowledge of the pest and available products are necessary to develop a plan of action. A few drops of kerosene on the surface of the local swamp will certainly kill mosquito wrigglers but for every kilo of wrigglers you kill you may kill 20 kilos of other wildlife, many of which fed on the mosquitoes. With the mosquito being the fastest breeder, next rain you will have more mosquitoes than ever and the other wildlife may never recover. Local governments may offer some assistance and of course, your local Direct Pest Control professional is available for expert management and advice.

There are 3 common genus of mosquito represented here, Anopheles, Aedes and Culex.

Anopheles spp. Note how this genus angles body when resting and feeding (Quick identification)

Includes Anophele. faranti, the Australian malaria mosquito found in northern Australia and A. annulipes which can be found right down to Victoria. Both these are potential carriers of malaria and myxomatosis.

 

Aedes spp. Rests and feeds with body parallel to surface

Includes Aedes vigilax, the salt-marsh mosquito and a vector for epidemic polyarthritis (Ross River fever) and probably dog heartworm. Aedes aegypti, the dengue mosquito lives close to your home in the Northern Territory and Queensland and is also a vector for dog heartworm. Other members of this group are vectors for yellow fever.

 

Culex spp. Rests and feeds with body parallel to surface

The common banded mosquito ( Culex annulirostris) found throughout Australia is strongly suspected of carrying Murray Valley encephalitis as well as Ross River virus. The brown house mosquito (C. quinquefasciatus) of Victoria is in the frame for dog heartworm.

In addition, many mosquitoes can carry filariases,
an unpleasant worm infestation in the tissues.

Below are 2 products on the market that can be
used kill annoying insects

 Click the diagrams above to enlarge

If you would like further information about these products,
contact your nearest Direct Pest Control Office