History and Facts
Mission
The Mission of Leon County Mosquito Control is to train and empower its employees to provide Leon County residents and visitors with effective and environmentally sound mosquito control services. Services and educational programs are provided to protect public health and reduce human discomfort associated with large mosquito populations.
LC Mosquito Control accomplishes its mission through source reduction, public education, larva and adult mosquito control services.
History
No animal on earth has touched more human lives than mosquitoes. More people have died from mosquito-borne diseases than all who have been killed in all the wars ever fought. All three thousand species are self-serving survivors. Mosquitoes predated humans by millions of years and are adept at surviving in almost all climates. Before mosquito netting was widely used, mosquitoes were the scourge of rich and poor alike. At first, only the wealthy could afford them, but as mosquito-borne diseases decimated farmers and peasants, mosquito nets were distributed throughout villages and towns.
Native tribes created and passed down tales of how mosquitoes came to be, usually involving blood-thirsty giants that walked the land. Native peoples discovered plants and other methods, like smoky fires to ward off the biting insects.
When Europeans arrived, so did some of the more deadly mosquito-borne diseases like malaria and yellow fever. Indians, who had no natural immunity to such diseases soon suffered epidemics that wiped out entire tribes. Early settlers struggled with growing crops and livestock while battling the insistent pest. Mosquitoes are drawn to carbon dioxide and particularly that of cattle. Swarms of them would fly up the nostrils of cows and suffocate them.
Until the realization that mosquito breeding occurred in standing water and draining and ditching began, those who could, would move entire families, tribes or villages to higher ground in the Carolinas or North Georgia until cooler weather made coastal and flat lands more habitable.
When one of Andrew Jackson's scouts came through Tallahassee in 1818, he reported a completely abandoned town, "except for an old Indian woman, recently dead, lying near ashes and a dirt pot." Florida almost didn't become a state because of mosquitoes. Northern states were reluctant to include the "land of flowers," in the union.
Truck spraying as a method of controlling mosquitoes has been around – though vastly revised for public safety – since the 1940s. As far back as the 1920’s larviciding, usually by floating diesel fuel on standing water was a common control practice. Environmentally safe and more effective products are currently in use.
Leon County Mosquito Control was organized as a separate division of Public Works in 1996. Until then, it was under Leon County Health Department and its primary responsibility was in maintaining drainage ditches where mosquitoes bred.
LCMC conducted the first project to control malaria in a war zone. During WWII, many international soldiers arrived for pilot training at the airfield where Tallahassee Community College now stands. County officials worried about strains of malaria entering the country.
Doak Campbell Stadium sits in what was a wetland. Dr. Andrew Rogers, a staunch “Gator” had it drained for mosquito control purposes and then had the irony of seeing a “Seminole” football field built on the grounds.
Leon County Mosquito Control is a “dependent” division, meaning it is funded by taxes through the Board of County Commissioners.
In Florida there are 73 species of mosquitoes, of those, only a dozen or so are considered of public health concern as disease vectors. Scientists estimate there are forty thousand mosquitoes for every person alive on earth.
Mosquito-borne diseases
Malaria
Malaria occurred in all 67 counties in Florida and was once a major scourge. Imported by European colonists, malaria-infecting mosquitoes made it into the New World in cargo and baggage and by people with the disease.
Malaria was definitely a problem in Leon County in the 1800's and early 1900's, with a death rate of 125-175 per 100,000 people. In the 24 counties having the highest death rates (Leon County included), these rates meant 20 – 60 percent of the population had malaria.
When Andrew Jackson arrived in Tallahassee in 1818, he described a “vacant town.” Native Americans and European settlers had fled, possibly to avoid the mosquito-borne malaria, or to escape the conquering military.
Malaria prevention and reduction methods: Those who could afford it often went north for the summer, to avoid exposure. Window screening was the single most effective and inexpensive tool introduced to fight malaria, as the disease-carrying mosquito would sleep in dwellings during the day and attack at night when residents were asleep. Mosquito sprays, agricultural and development drainage practices and the use of anti-malarial drugs effectively curtailed outbreaks of the disease in Florida. Until its use was banned, DDT was used in the ten counties with the highest malaria death rates.
Yellow Fever
Tallahassee suffered from three epidemics of yellow fever in 1841, 1853 and 1867. But problems with mosquito-born diseases appear to have been much greater in large coastal cities like Tampa and Jacksonville. There was no case of yellow fever reported in the U.S. in 2006.
West Nile Virus
West Nile Virus is spread through the bite of some Culex mosquitoes, and is closely related to St. Louis Encephalitis virus. West Nile Virus was discovered in New York City in 1999 and has since become established in the West Hemisphere. West Nile virus was commonly found in humans, birds and other vertebrates in Africa, Eastern Europe, West Asia and the Middle East.
Less than one percent of humans bitten with a West Nile virus infected mosquito will become ill. It is estimated the majority of the population have been infected and remained symptom-free, or had mild flu-like symptoms. West Nile Virus severe illness occurs mainly in the very young or the elderly.
There were no human West Nile Virus cases reported in 2006 in Leon County.
St. Louis Encephalitis
First recognized in St. Louis, Missouri in 1933, epidemics of SLE have occurred in Florida, Central and South America. Even during epidemics, only a small proportion of people infected with SLE become ill. Substantial numbers of people are infected with SLE virus, but do not develop the disease. The virus is a permanent resident of Florida. Transmission is via wild birds bitten by a Culex nigripalpus, a SLE-carrying mosquito. The bird develops sufficient quantities of the virus to pass it one to another biting mosquito, then to humans. Frequency and severity of SLE symptoms are greater in those under ten years old or older than 60.
Sentinel chicken flock monitoring indicates when SLE antibodies are present and alerts Mosquito Control to the possibility of a SLE outbreak. Surveillance and mosquito breeding sites are key to controlling SLE incidences.
Mosquito habitats
Mosquitoes breed in permanent fresh and salt waters, floodwaters and containers. Not all species react to the same control chemicals.
Mosquito Species
In Leon County, there are 43 different species of mosquitoes. The Asian Tiger Mosquito, Aedes albopictus is the most common in urban areas. It was imported in used tires that were recycled and shipped to the U.S. from Asia.
Methods of control
Larviciding
Larviciding refers to a technique used to kill mosquito larvae. One method of larvicide is the use of non-toxic Bacillus thuringiensis israelensis (Bti) in briquette or pellet form. A second larval control material is a corncob granule formulation of Bacillus sphaericus (Bs). Bs is highly specific to Culicine and Anopheline mosquitoes. It is also very safe for non-targets and provides longer protection than Bti, but is relatively ineffective against Aedine mosquitoes. Other means include the insect growth regulator, methoprene, applied to specific, difficult to treat locations and the monomolecular surface film, Agnique, that is effective against pupae. Finally, predatory mosquitofish can be introduced to stand-alone ponds and pools.
Source Reduction
Source Reduction is the low-tech method of mosquito control and involved the cooperation of residents who are vigilant about emptying standing water found in ordinary objects like birdbaths, pet dishes, old tires and the like. LCMC conducts free inspections of properties to locate the source of mosquito breeding. Through community education, residents learn how to make their outdoor spaces less mosquito-friendly.
Adulticiding
Adulticiding refers to a technique used to kill adult mosquitoes.