The Mosquitoes: Over 70 species of mosquitoes have been found in Florida, and more than 40 species have been identified in Pasco County. Each mosquito species has a different habitat, behavior and preferred source of blood. Organized mosquito control is necessary because mosquitoes are not only a nuisance as biting insects, but are also involved periodically in transmitting diseases to humans and animals.
Mosquitoes Need Water: All mosquitoes have four stages of development - egg, larva, pupa, and adult - and spend their larval and pupal stages in water.
While some mosquitoes lay their eggs on the surface of the water, the most abundant species deposit their eggs on moist soil. These eggs may lie dormant for several months and even years and will not hatch until they are covered by rain water or tides. Four to five days after the eggs hatch, the larvae are full grown. By this time, they have changed their shape - become less active - and are known as pupae. After one to two days, the pupal skin splits at the water's surface, and the adults emerge and are soon ready to bite.
Only the Females Bite: When an adult mosquito emerges from the pupa, they mate, and the female seeks a blood meal to obtain the protein necessary for the development of her eggs. With one blood meal, a female may produce as many as 250 or more eggs. After a blood meal, it takes 3-5 days for blood to be digested and the eggs to develop.
The male mosquito does not take a blood meal, but may feed on plant nectar. He lives for only a short time after mating, while the female can live for over two weeks, producing 2-4 egg batches. Females transmit diseases when they live long enough to spread viruses, microfilaria, etc. from the first blood meal victim to the second blood meal victim. Only a very small percentage of mosquitoes live this long.
Females seek a place to lay their eggs, and the site chosen is probably based on clues from chemical receptors on their body. Mosquitoes have two general egg laying (oviposition) strategies which are usually specific for each species. Mosquitoes will either lay eggs on existing water bodies, or they will lay eggs at sites that will later be flooded. In either case, the egg requires 1-2 days of water before the 1st instar larvae are released. The female mosquito stores the sperm she received through mating, and eggs are fertilized at the time they are laid. The development time of the egg is about 1-2 days, and during this period the egg turns from white to black as its outer shell hardens to protect it from a hostile environment. Some eggs may hatch several months and even years after they are laid if they are not exposed to water during that time.
The next stage is the pupa, or tumbler. This stage usually lasts about 2 days. During this time the mosquito transforms from the aquatic larva into the flying adult. The pupa does not feed. If you look carefully at a pupa through its semi-transparent exoskeleton, you will see the developing adult inside. After a suitable development time, the adult emerges from the exoskeleton at the water surface, dries its wings, and takes flight to begin the cycle again.
The mosquito must breathe air to live. In both the larval and the pupal stage, the mosquito takes advantage of the surface tension of the water to stay attached to the surface layer so that they may gather air through special appendages called "siphons" for larvae and "horns" for pupae. Adults also use the water surface tension to stay suspended when they are emerging from pupal cases, drying their wings, and/or landing and laying their eggs.