Did you know that when you are bitten by a mosquito that it is a female mosquito doing the biting? Male mosquitoes limit their feeding to plant juices and nectar from flowers and fruit. Female mosquitoes feed on these sources for energy also, but need a protein-rich blood meal to stimulate egg laying.
Mosquitoes are a very prevalent group of blood sucking insects afflicting man and other mammals. They are found throughout the world in almost every natural collection of water – from mines almost 4,000 feet below ground to 14,000 feet above the earth's surface. In the United States and Canada alone, there are 174 different mosquito species. There are 80 different species here in Florida. In Charlotte county, we have approximately 40 species.
All mosquito species require aquatic habitats for development during the larval and pupal stages. It is during the larval stage the mosquito is vulnerable to the soil bacteria Bacillus thuringensis var. israelensis (Bti). See also Larviciding Efforts
Habitats which support mosquito breeding here in Florida include swamps, marshes, rain puddles, tree holes, plant axils, ditches, and even man-made containers such as abandoned tires (see also Mosquito Control At Home
). Increasing land development has led to more storm water runoff, detention basins, and storm sewers. These are creating additional aquatic environments capable of supporting mosquito life.
The mosquito's life span varies widely. In some species, about one-third of the adult population dies daily. While the male typically lives for only about 2 weeks, the female may survive for 6 weeks to 5 months, depending on the species and the time of year.
Females compensate for high mortality rates by laying large numbers of eggs – between 100 and 250 eggs at a time. She is able to lay 4 to 5 broods of eggs in her short lifetime. Depending on the species, the female lays her eggs either individually or in clusters referred to as "rafts." She deposits the eggs on the surface of still water, on the sides of water-holding containers right above the water level, or on moist soil prone to flooding. Moisture catalyzes hatching and development. Mosquito eggs can lie dormant for up to several months, even a year or more at a time until water washes over them.
After the eggs hatch, the mosquito enters into a strictly aquatic phase, the larval stage. Commonly called a "wiggler" or "wriggler" because of its characteristic S-shaped swimming motion, the larva feeds on aquatic microorganisms. Many species suspend themselves immediately below the water surface during this stage in order to breathe. To do this, they extend a snorkel-like tube called a siphon, located at the end of their bodies, piercing the surface of the water to obtain air.
The larva grows and sheds its skin – or molts – four times over a 4 to 21 day period before entering the pupal stage, also an aquatic phase. An even more active swimmer, the pupa is commonly called a "tumbler", describing the tumbling motion it uses to dive into deeper water. During this stage of development, the mosquito does not eat. Like the larva, the pupa also uses a snorkel-like device for breathing called a trumpet.
After 2 to 8 days, the pupa finishes its development and a winged adult emerges on the water's surface, where it must dry it wings. This new adult is capable of flying up to 20 miles or more from its breeding site. After mating, most female mosquitoes require a small amount of blood to nourish their eggs, commonly called a bite. After her blood meal, the female lays her eggs and the mosquito life cycle begins again.
The Department takes advantage of the knowledge of this life cycle to help in the efforts to control these pests. The most environmentally sound and most effective method of mosquito control is an integrated program that reduces breeding sites and applies biological controls, such as Bti during the larval stage. This is known as larviciding
. During this stage, these insects are concentrated in well defined aquatic areas. In contrast, adult mosquitoes after they disperse from the breeding sites are difficult and costly to control.
Eliminating the potential breeding sites, or source reduction, is one of the most effective means of controlling mosquitoes. A number of source reduction measures homeowners can take advantage of are listed in Mosquito Control At Home
When all other attempts at controlling mosquito larvae fall short and the numbers of mosquitoes becomes overwhelming, adulticide treatment
by aerial or ground spraying is necessary. State guidelines must be met before the Department can schedule any adulticide treatments.
While some mosquito species pose no threat, others have altered world history through the transmission of dreaded diseases
to humans and animals. Among these are malaria, dengue, dengue hemorrhagic fever, yellow fever, filariasis, and encephalitis. Of these diseases, the various strains of encephalitis virus are the most serious in the United States.
In Florida and Charlotte county, our main concern is with St. Louis Encephalitis (SLE)
Eastern Equine Encephalitis
West Nile Virus
, and now
, all of which are spread by fresh-water mosquitoes.