Mosquito FAQ

No.  Indian River Mosquito Control District is a special taxing district that is governed by a separate Board of Commissioners and Director.  The District was the first of its kind in Florida, created by an act of the legislature in 1925.

IRMCD is not responsible for ditch, swale or canal maintenance.  Depending upon where you live, you may need to contact your homeowner’s association, the respective city or county Public Works departments or the local water management district to address any maintenance concerns.

Because of the tremendous human resources required to inspect and treat mosquito larvae, we restrict our larval control efforts to the two species of salt marsh mosquito which are produced primarily east of US 1.  It is imperative to stop these mosquitoes at the larval stage because, as adults, they are incredibly pestiferous and capable of flying up to 25 miles.

The yellow crop duster applies granular larvicides to the marshes along the river to kill these pestiferous salt marsh mosquitoes at the larval stage, before becoming adults.  The aerial larviciding efforts are focused on the two species of salt marsh mosquito which are produced primarily east of US 1. 

The type of mosquitoes that are capable of transmitting dengue, chikungunya and Zika are not found in standing water directly on the ground, in swales and ditches.  They inhabit containers such as buckets, rain barrels, tires, plant saucers, and children’s toys that are capable of holding water.  Refer to Homeowner Tips for areas around your home to check.

The Florida Department of Health has created a webpage with a variety of resources for the public and health care community.  Each day the Health Department updates the website and issues press releases with case count information for the state.  The Center for Disease Control is also a great reference on Zika.

Please contact our office and provide us with the address of the home.  We will dispatch an inspector to the site to evaluate the area and provide treatment if necessary.  Typically, an inspector will place native mosquito fish (minnows) into the pool for control.

Here are some tips for preventing mosquito bites.

• Wear long-sleeved shirts and long pants.
• Use Environmental Protection Agency (EPA)-registered insect repellents. When used as directed, these repellents are proven safe and effective, even for pregnant and breastfeeding women.

• • Always follow product label instructions and reapply as directed.
  • Do not spray repellent on the skin under clothing.
  • If you are also using sunscreen, apply sunscreen first.

• Stay in places with air conditioning or that use window and door screens.
• Eliminate standing water in containers in and around the home.
• Sleep under a mosquito bed net if air conditioned or screened rooms are not available or if sleeping outdoors.
• Dress children in clothing that covers arms and legs.
• Apply insect repellent to children (but not babies younger than 2 months).
• Spray insect repellent on hands to apply to a child’s face.
• Cover cribs, strollers, and baby carriers with mosquito netting.

Are you growing your own mosquito larvae around your house?  Check around your house and property looking for containers, natural or manmade, that may hold water.  Refer to the Homeowner Tips  page for areas to check and to the Home-Grown Mosquitoes video to be able to recognize what mosquito larvae look like.

Depending upon the species, mosquitoes can fly at about 1 to 1.5 miles per hour. 

Domestic mosquito species, like the Asian tiger mosquito, have limited flight ranges of about 300 feet. Most species have flight ranges of 1-3 miles. Salt marsh mosquitoes can migrate from 20 to 40 miles, and up to 100 miles in exceptional circumstances. 

Female mosquitoes need to obtain a blood meal so that their eggs can mature prior to laying. It serves no nourishment function. Males do not take blood meals at all. In order to obtain energy, both male and female mosquitoes feed upon plant nectars - much in the same manner as honeybees. 

Mosquitoes fill a variety of niches which nature provides. As such, placing a value on their existence is generally inappropriate. Although the fossil record is incomplete, they have been known from the Cretaceous Period (about 100 million years ago) in North America. Their adaptability has made them extraordinarily successful, with upwards of 2,700 species worldwide. Mosquitoes serve as food sources for a variety of organisms but are not crucial to any predator species. 

Lifespan vary by species. Most adult female mosquitoes live 2-3 weeks. Some species that over-winter in garages, culverts and attics can live as long as 6 months. 

Why some people seem to be more attractive than others to mosquitoes is the subject of much research being conducted nationwide. Carbon dioxide is the most universally recognized mosquito attractant and draws mosquitoes from up to 35 meters. When female mosquitoes sense carbon dioxide they usually adopt a zigzagging flight path within the plume to locate its source. Once in the general vicinity of a potential host, other cues are utilized, including body odors (sweat, lactic acid, etc.) and heat.

DEET (N,N-diethyl-3-methylbenzamide) remains the standard by which all other repellents are judged. DEET was developed by the U.S. Department of Agriculture and was registered for use by the general public in 1957. It is effective against mosquitoes, biting flies, chiggers, fleas, and ticks. Over 25 years of empirical testing of more than 20,000 other compounds has not resulted in another marketed chemical product with the duration of protection and broad-spectrum effectiveness of DEET although the recent additions of picaridin and oil of lemon eucalyptus are remarkably close in effectiveness to DEET.

Picaridin is a synthetic developed by Bayer Corporation in the 1980s. This repellent is the most widely used repellent in the world outside of the United States and is marketed as Cutter Advanced. Picaridin is odorless, has a pleasant feel and doesn't plasticize like DEET. Studies have shown it to be as fully repellent to mosquitoes as DEET and can also be applied on infants as young as 2 months. The 15% picaridin formulation, Cutter Advanced Sport, is also an effective repellent for ticks.

The other repellent, often the choice of those wanting a natural product, is oil of lemon-eucalyptus, sold as Repel®. Repel is a 40% formulation of naturally-derived eucalyptus and has a pleasant scent and feel without any plasticizing properties. It is also effective at repelling ticks. 

Mosquito coils and Therma-cell devices can also provide some protection. Both utilize a synthetic pyrethroid insecticide that has repellent properties, but are most effective in situations of little wind, where the repellent mixture remains in place in the air column surrounding the body. The Therma-cell is a favorite among hunters. 

Refer to the Brochures & Fact Sheets page to review documentation on review of repellents.  For additional information, please refer to the Center for Disease Control and Prevention’s website.

Mosquitoes are singularly adept at entering houses through any portal available, be it through broken window or door screens, attic soffits or through bathroom exhaust vents. A favorite resting spot is the garage, so take care to keep resting female mosquitoes from coming into the house through the garage. 

If possible, schedule your activities to avoid the times when mosquitoes are most active - usually dawn and dusk. You should also dress in light, loose-fitting clothing. Refer to the Homeowner’s Tips page for more information.

If you have a deck, light it using General Electric yellow "Bug Lights". These lights are not repellants, but do not attract mosquitoes like other incandescent lights. Mosquitoes are relatively weak flyers, so placing a large fan on your deck can provide a low-tech solution. Citronella candles have a mild repellent effect, but do not offer significantly more protection than other candles producing smoke. 

Scheduled sprays used by these misters may needlessly broadcast pesticides into the environment, affecting mosquitoes and non-target insects alike. Modern mosquito control strategies emphasize an integrated approach. Effective mosquito control requires continual survey of adult mosquito densities to determine if certain triggers for control are met. This reduces the use of adulticides to only those times when they are required. 

Black light insect electrocution devices (Bug Zappers, etc.) are purchased in huge quantities by homeowners due to their demonstrated ability to attract and kill thousands of insects over a 24 hour period. Bug zappers do indeed kill some mosquitoes. However, the only two controlled studies conducted to date by independent investigators at the University of Notre Dame showed that mosquitoes comprised merely 4.1% and 6.4% respectively of the daily catch over an entire season. Even more important was the finding in both studies that there was no significant difference in the number of mosquitoes found in yards with or without bug zappers.

Mosquitoes continue to be more attracted to humans than to the devices. One study conducted in homeowners' backyards showed that of the insects killed by these devices, only 0.13% were female mosquitoes. Non-pest insects that comprise the vast majority of trap catch. Many of these insects are beneficial predators on other insect pests. They in turn constitute a major part of the diet of many songbirds. An estimated 71 billion to 350 billion beneficial insects may be killed annually in the United States by these electrocuting devices.

At least 10 studies in the past 15 years have unanimously denounced ultrasonic devices as having no repellency value whatsoever. A pioneering study testing five different ultrasonic devices against four mosquito species convincingly demonstrated that ultrasound in the 20-70 kHz range used by these devices had no effect on reorienting flight by female mosquitoes either toward or away from human subjects. Additional tests have shown that sound generators capable of a wide range of frequencies were also ineffective in repelling mosquitoes. The fact is that these devices just do not work - marketing claims to the contrary

Recently the public has shown increased interest in the value of insectivorous species of bats in controlling mosquitoes. Although untested lately, this is not a new idea. During the 1920's several bat towers were constructed near San Antonio, Texas, in order to help control malarial mosquitoes. Mosquito populations were not affected and the project was discontinued.

Bats in temperate areas of the world are almost exclusively insectivorous. Food items identified in their diet are primarily beetles, wasps, and moths. Mosquitoes have comprised less than 1% of gut contents of wild caught bats in all studies to date. Bats tend to be opportunistic feeders. They do not appear to specialize on particular types of insects, but will feed on whatever food source presents itself. Large, concentrated populations of mosquitoes could provide adequate nutrition in the absence of alternative food. However, a moth provides much more nutritional value per capture than a mosquito.

M.D. Tuttle, a world authority on bats, is often quoted for his anecdotal report that bats effectively controlled mosquito populations at a popular resort in New York State. While there is no doubt that bats have probably played a visible, if not prominent, role in reducing the mosquito problems in many areas, the natural abatement of mosquito populations is an extremely complex process to study, comprising poorly known ecological relationships. Tuttle attempts to underscore the bats role by citing an experiment in which bats released into a laboratory room filled with mosquitoes caught up to 10 mosquitoes per minute. He extrapolated this value to 600 mosquitoes per hour. Thus, a colony of 500 bats could consume over a quarter of a million mosquitoes per hour. Impressive numbers indeed, but singularly unrealistic when based upon a study where bats were confined in a room with mosquitoes as their only food source. There is no question that bats eat mosquitoes, but to utilize them as the sole measure of control would be folly indeed, particularly considering the capacity of both mosquitoes and bats to transmit diseases. 

It has been known for many years that bird species like purple martins consume large numbers of flying insects. Proponents of their use in mosquito control are quick to cite J. L. Wade, an amateur ornithologist, who reasoned that an average 4 ounce adult purple martin, due to its rapid metabolism, would have to consume its body weight (14,000 mosquitoes) per day in order to survive. Wade recognized that the purple martins diet includes many other types of insects, but this appears to have been lost on many individuals searching for a natural means of control. In fact, during daylight, purple martins often feed voraciously upon dragonflies, known predators of mosquitoes. At night, when mosquitoes are most active, purple martins tend to feed at treetop level, well above most mosquito flight paths.

Ornithologist James Hill, founder of the Purple Martin Conservation Association (PMCA), writes, "The number of mosquitoes that martins eat is extremely insignificant, and they certainly don't control them. In-depth studies have shown that mosquitoes comprise no more than 0 to 3 percent of the diet of martins". They eat only flying insects, which they catch in flight. Their diet is diverse, including dragonflies, damselflies, flies, midges, mayflies, stinkbugs, leafhoppers, Japanese beetles, June bugs, butterflies, moths, grasshoppers, cicadas, bees, wasps, flying ants, and ballooning spiders.

Martins are not, however, immense consumers of mosquitoes as is so often claimed by companies that manufacture martin housing. An intensive 3-year diet study conducted at PMCA headquarters in Edinboro, PA, failed to find a single mosquito among the 350 diet samples collected from parent martins bringing beakfuls of insects to their young. The samples were collected from martins during all hours of the day, all season long, and in numerous habitats, including mosquito-infested ones.

Purple Martins and freshwater mosquitoes rarely ever cross paths. Martins are daytime feeders, and feed high in the sky; mosquitoes, on the other hand, stay low in damp places during daylight hours, or only come out at night. Since Purple Martins feed only on flying insects, they are extremely vulnerable to starvation during extended periods of cool and/or rainy weather. Rather than erecting martin houses to specifically attract insect-eating birds for mosquito control, we should at least promote them for their aesthetic and educational value. 

The integrated mosquito management methods currently employed by organized control districts and endorsed by the CDC and EPA are comprehensive and specifically tailored to safely counter each stage of the mosquito life cycle. Larval control through water management and source reduction, where compatible with other land management uses, is a prudent pest management alternative - as is use of the environmentally friendly EPA-approved larvicides currently available. When source elimination or larval control measures are clearly inadequate, or in the case of imminent disease, the EPA and CDC have emphasized in a published joint statement the need for considered application of adulticides by certified applicators trained in the special handling characteristics of these products. 

A successful mosquito management program should include the following elements:

• larval and adult mosquito sampling;
• source reduction techniques;
• biological control using native or introduced predators and parasites of mosquitoes,
• larviciding and adulticiding, when indicated by surveillance;
• resistance monitoring;
• disease surveillance in mosquitoes, birds, horses and humans,
• public education.

Since its inception, the Environmental Protection Agency (EPA) has regulated mosquito control through enforcement of standards instituted by the Federal Insecticide, Fungicide, and Rodenticide Act. This legislation mandated documentation of extensive testing for public health insecticides according to EPA guidelines prior to their registration and use. These data requirements are among the most stringent in the federal government and are met through research by established scientists in federal, state and private institutions.

This process costs a registrant several million dollars per product, but ensures that the public health insecticides available for mosquito control do not represent health or environmental risks when used as directed. Indeed, the five or six adulticides currently available are the selected survivors of literally hundreds of products developed for these uses over the years. The dosages at which these products are legally dispensed are at least 100-fold less than the point at which public health and environmental safety merit consideration. In point of fact, literature posted on the websites of the EPA Office of Pesticide Programs, Centers for Disease Control and Prevention (CDC), American Association of Pesticide Safety Educators and National Pesticide Information Center emphasizes that proper use of pesticides by established mosquito control agencies does not put the general public or the environment at unreasonable risk from runoff, leaching or drift when used according to label specifications. (For the federal government's position on risks associated with mosquito control insecticides, visit http:/www.epa.gov/pesticides). 

The safety profiles of public health insecticides are undergoing increasing scrutiny because of concerns with how the specialized application technology and product selection protect the exposed public and environment. In fact, well over 200 peer-reviewed scientific studies in various national and international refereed journals since 1980 have documented the safety and efficacy of these public health insecticides at label rates in addition to their application techniques. 

The extremely small droplet aerosols utilized in adult mosquito control are designed to impact primarily on adult mosquitoes that are in flight at the time of the application. Degradation of these small droplets is rapid, leaving little or no residue in the target area at ground level. These special considerations are major factors that favor the use of very low application rates for these products, generally less than 4 grams active ingredient per acre, and are instrumental in minimizing adverse impacts.