The Basics of Mosquitoes (continued)

Immediately when the weather warms to the mid to high 60's, even if it is a sudden warm spell in the middle of the winter, mosquito adults are out and about, the females looking for a blood meal and then a water source to lay her eggs. It may even be containers, such as buckets or tree holes, that do not yet have water in them, and yet the mosquito instinctively knows these cavities will fill up later, and she lays her eggs in them. The eggs may be deposited in clusters on top of the water (called "rafts") or one at a time on the surface of an object.

The eggs hatch into tiny larvae, and we call this stage "wrigglers" because of the way in which they move around in the water, wriggling back and forth rapidly to go up, down, or sideways. Even though they live in the water they still must breathe air, and they do so by going to the surface of the water frequently, and sticking their breathing tube up to the air above. This habit allows professionals to use some excellent materials on the surface of the water, to prevent the larvae from making this connection to the air.

After only a few days as a larva, which undergoes several stages and sheds its skin each stage in order to grow larger, it develops to the pupa stage. This is called a "tumbler", because it too is active (although it does not feed) and tumbles around in the water to go to the bottom for protection and back to the surface to breathe. Finally, it floats to the top and the adult mosquito sheds the pupa skin and steps out as the fully developed, winged insect that we all know and love so well. Even though you may often find mosquitoes resting in wet grass or shrubbery, it is not possible for them to develop there as larvae, and it is small or large pools of water that are necessary.

Why are mosquitoes important?

Without a doubt everyone in the world understands that mosquitoes bite us, removing some of our blood in the process. This biting is at the very least an annoyance to all of us, and a severe problem to some people whose immune systems may react more violently to the bite. In the worst case scenario the bite can be life-threatening, as mosquitoes spread numerous diseases that can kill. We are extremely fortunate in the United States to have had many years of mosquito control programs in effect that have virtually eliminated the most serious diseases from this country. Hopefully they will not return.

In the past Yellow Fever and Malaria were very, very common in the U.S., and at this time it is believed that they are not occurring at all from the bites of mosquitoes here. Frequently people traveling to other countries will come down with Malaria, but they acquired it in that other country. This still is a concern, however, since we still have many species of mosquitoes capable of spreading those diseases, and if an infected person is fed upon by the proper species, that mosquito may be capable of passing the disease on to a second person, should it feed a second time.

How is the disease spread?

When mosquitoes bite us they first inject a little bit of their saliva. This serves two functions important to the mosquito. First, it numbs the skin (anesthetizes it) so we often do not feel the bite, and the mosquito can feed undisturbed for a minute or so. Second, the saliva is an anti-coagulant, and it keeps the blood from clotting as the mosquito feeds on us. Our bodies do not like the saliva in them, and our normal reaction is to swell up at the site of the bite, and begin to itch. The more we scratch the more it itches, and the larger the bump gets.

Within the saliva of the mosquito there may be bacteria or viruses that can cause us to come down with illnesses. These microscopic pathogens are intimately associated with the mosquito, and actually MUST be within the mosquito as part of their own life cycle. To pick Encephalitis as an example, a female mosquito feeds on an infected bird, and ingests a quantity of the virus that causes encephalitis. The viruses move into the wall of the stomach of the mosquito, and propagate there awhile, growing to large numbers. They then move to the salivary glands of the mosquito where they can be passed out the next time the mosquito bites an animal, allowing them to reproduce and grow within this new host, ensuring their survival.

It is because of this "intimate" association between pathogen and mosquito that scientists believe many other diseases cannot be spread by mosquitoes (or fleas, ticks, bedbugs, etc.). Despite wild headlines suggesting that AIDS is spread by mosquitoes, intense study by University scientists shows that it simply cannot happen.