Adult mosquitoes (flies belonging to the family Culicidae) are winged, terrestrial insects, while their immature stages (eggs, larvae, and pupae) are aquatic. Larvae and pupae are strictly aquatic, but the eggs of some mosquito species are laid in damp places to await flooding before larvae can hatch from them.
Larvae molt their skins four times during their development and, at the fourth molt, they become pupae. Adult females of most mosquito species take blood from warm-blooded animals: this provides proteins needed for the development of eggs. Adult male mosquitoes, and females of some species, do not take blood. Adult mosquitoes of both sexes feed on plant nectars which they use as an energy source. Mosquito larvae feed by filtering particles from the water, by rasping particulate debris from underwater surfaces, or by preying on other small organisms, depending upon the species. Eggs and pupae do not feed. In general, all stages (eggs, larvae, pupae, adults) of mosquitoes are short-lived, but there are exceptions.
As of 1995, 78 mosquito species in 12 genera inhabit Florida. Almost all are considered native. Few of them are associated in any way with bromeliads. In the USA, two journals are dedicated to publishing information about mosquitoes. They are Journal of the American Mosquito Control Association (formerly Mosquito News), and Journal of the Florida Mosquito Control Association (formerly Journal of the Florida Anti-Mosquito Association).
Mosquito-borne Diseases
The animal (or person) on which an adult female mosquito feeds is termed the host. Adult female mosquitoes of some species are capable of transmitting certain infectious diseases from host to host. Diseases are caused by protozoa, nematodes, and viruses.
Malaria is caused by parasitic protozoans, and is transmitted by some Anopheles mosquitoes. Filariasis and dog heartworm are caused by parasitic nematodes, and are transmitted by some Aedes and Culex species. Yellow fever and dengue are caused by viruses, and are transmitted mainly by some Aedes mosquitoes. Viral encephalitides such as Eastern Equine encephalitis (EEE) and St. Louis encephalitis (SLE) have been transmitted in Florida by some Culex mosquitoes.
Whether a particular female mosquito carries such a disease organism depends upon its previous exposure to the disease. Yellow fever, malaria, and dengue have been eradicated from Florida by control of mosquitoes carrying them, but all three diseases exist in parts of South America. Though the diseases are no longer present in Florida, the mosquito species which might transmit them (if they were here) are still present.
The viral encephalitides (EEE and SLE) are not uncommon in wild birds in Florida. From time to time these diseases are transmitted from bird populations to human and horse populations by Culex mosquitoes. Outbreaks in Florida of SLE in 1990 and EEE in 1991 received a lot of news coverage. During outbreaks of these dangerous diseases, personnel of Florida's mosquito control districts monitor the diseases and use all legal means to suppress the mosquitoes capable of transmission.
Monitoring the diseases is accomplished by use of "sentinel chickens." Chickens are placed in outdoor cages, and their blood subsequently is tested for presence of the virus. Mosquitoes caught in traps may likewise be checked for presence of virus. Finally, medical practitioners are required to report human cases of the diseases. The "sentinel chicken" method is relied upon heavily and can give advanced warning of local incidence of the diseases before human cases occur. Checking individual mosquitoes is a much more laborious method.
Physical methods ("source reduction") are used to reduce the habitat available to mosquito larvae and pupae wherever possible. Chemical pesticides, microbial pesticides, and biological control agents also are used against mosquito larvae and pupae. Chemical pesticides applied by aircraft, trucks, and manually-operated sprayers are used against adult mosquitoes. Mosquito control district personnel have the right to inspect private properties for sites producing disease-transmitting mosquitoes, and they can take legal action against property owners who allow conditions conducive to production of such mosquitoes (5).
