Our Neighborhood Was Once Named Mosquito County

Dated: December 5 2023

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In the early 1920s when the MacWilliam family settled in present-day Vero Beach, the area was part of Mosquito County which included present-day Volusia, Brevard, Indian River, St. Lucie, Martin, Seminole, Osceola, Orange, Lake, Polk and Palm Beach counties. The area was aptly named since a large portion of the land contained wetlands; the perfect habitat for mosquito breeding. Alex MacWilliam, Sr. was instrumental in creating Indian River County, and he is also credited with recognizing the need for local mosquito control. His efforts led to the creation of the Indian River Mosquito Control District (IRMCD) in 1925, the first such taxing district in Florida.

Through the years, the IRMCD has perfected methods used to reduce mosquito numbers in our area. In the mid-1940s here on the coast of Florida, the Navy loaded up their airplanes with DDT and sprayed it aerially over the Naval base. This mosquito control method was so effective that they started spraying our entire county. At the time, DDT was used with great results to combat malaria, typhus, and other insect-borne human diseases. In the late 1950’s, there was mounting evidence of the pesticide's declining benefits and negative environmental and toxicological effects, so the IRMCD began experimenting with other methods of control.

To understand how to control mosquitoes, we first needed to understand their life cycles. Mosquitoes are two-winged flies that live in humid tropics and subtropics, warm moist climates, temperate and cool zones - everywhere except areas that are permanently frozen. Globally, there are about 3,500 species of mosquitoes with 80 species occurring in Florida. Mosquitoes develop through four different forms during their life: egg, larva, pupa, and adult. To grow, the eggs require either floodwater or permanent water. Floodwater eggs are laid on damp soil and surfaces, not on standing water, and while they need water to hatch, they must dry out first. Permanent water eggs are laid on the water surface and do not survive if they dry out. During the larval stage, as the larvae grow, they shed their skin (molt) four times and each stage is called an instar. Larvae develop into pupae which are active swimmers, but they do not eat anything during the short time they are in this stage. The larval and pupal stages of the mosquito are aquatic; the adult is terrestrial. Once the mosquitoes emerge as adults, they can fly after their wings dry out. 

Mosquitoes fly to mate, find blood sources, escape predators, lay eggs and to find resting places. The frequency of the mosquito wing beat ranges from 300 – 600 beats per second. Males and females of the same species recognize each other by listening to wing beat frequency. Flight activity is reduced at temperatures around 60°F, and mosquitoes are inactive at 50°F and lower. How far a mosquito flies from the aquatic habitats varies with species. Some go only 500 feet from where they emerged; some can move up to 40 miles from the larval habitat.

Female mosquitoes need blood to nourish their developing eggs. Some species can develop their first batch of eggs without a blood meal. The source of blood for female mosquitoes varies depending on host availability and mosquito species. After feeding on blood, the female mosquito needs to find a resting spot while her body digests the blood, this can take up to three days. She looks for dark, shady, well protected areas to rest to avoid being eaten and to stay warm and humid. When the female mosquito has digested a blood meal and is ready to lay eggs, she is attracted to various water sources. Some mosquito species are very picky about where they lay their eggs and will search until they find the perfect water source.

Studies have shown that source reduction is the most important technique that can be used to negatively impact mosquito populations. To reduce the source of mosquito breeding habitats, the IRMCD began building dikes around salt marshes in the 1950s and 1960s. The dikes kept water levels high enough to cover the mud where mosquitos typically laid their eggs. This was the beginning of modern mosquito control. The Florida Legislature passed a bill which matched funding for these types of mosquito control efforts by 75%. They also established the Florida Medical Entomology Lab (FMEL) right here in Vero Beach. Scientists at the FMEL field lab began studying the transmission of insect-borne diseases such as malaria, yellow fever, dengue fever, encephalitis, West Nile and other viruses that affect humans and animals. Today, the FMEL is one of the world's largest research institutions devoted to the understanding and control of medically important and biting insects. Their studies have enabled a much better control of insects on a worldwide basis.

Now, the IRMCD uses integrated pest management to control mosquito populations in our area. The most common technique still being used is source reduction – remove conditions and areas that mosquitoes are attracted to for egg laying. Keeping water impounded or diked has been a cost-effective method reducing the use of chemicals, however it was not natural for salt marshes to be disconnected from water flowing in and out of them via the estuary. As a result, the IRMCD has added culverts and water control structures enabling better management of water levels within the impoundments. They can keep the marshes open to water flow much of the year which benefits both the fish and animals that rely on salt marsh habitat while also keeping mosquito populations under control.

For more information about ways that you can help with mosquito control go to www.irmosquito.com.

Article authored by Camille Yates

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Kyle Von Kohorn

Born and raised in Vero Beach, FL, Kyle Von Kohorn is remarkably well-acquainted with this lovely coastal town and its satellite communities. After earning his degree in Business Administration at ....

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