Mosquito Control Methods
Bti, a naturally-occurring product in pellet form, is loaded into a helicopter for application into mosquito breeding areas.
Bti is a safe, naturally-occurring product in pellet form that’s nontoxic to people, pets, farm animals, and pollinators.
Staff from DEM, Rhode Island Department of Health and Rhode Island Emergency Management help with response efforts to supress mosquito populations.
This method is one of our most effective tools to reduce the number of biting mosquitoes by preventing the larval stage from maturing into adults. The product used in the applications is called Bti, a naturally-occurring bacterium that comes in a granular form. The EPA has concluded through a variety of studies that Bti does not pose a risk to humans. Bags of Bti was loaded onto a helicopter, which disperses the granules/pellets with precision in swamps and other breeding habitats to control mosquitoes breeding. Bti produces toxins that specifically affect the larvae of only mosquitoes, black flies and fungus gnats. These toxins do not affect other types of insects including honey bees. It is approved for pest control in organic farming operations.
Sometimes the state and/or local communities ground or aerial spray pesticide to control mosquitoes in a variety of environments such as outdoor residential and recreational areas, commercial urban areas, and rural areas. Mosquitoes are a nuisance that impact quality of life, and they also can carry diseases, such as Eastern Equine Encephalitis (EEE) or West Nile Virus (WNV). Aerial spraying was last conducted during the 2019 season.
When is aerial spraying of insecticides considered?
In situations where there is an elevated risk of human disease, state or local officials may consider the use of an aerial pesticide spray in the evening and overnight hours to reduce the number of infected, adult mosquitoes in the specific areas of elevated risk. Many breeding areas of high concern are not accessible by truck-mounted ground sprayers. It should be noted that although the aerial spraying is considered necessary to reduce human risk, it will not eliminate risk. It is critical that residents protect themselves from mosquito bites by staying indoors during peak mosquito hours, applying insect repellent when outdoors, draining standing water where mosquitoes breed, repairing screens, and protecting animals and pets.
How is aerial spraying conducted?
Aerial spraying is conducted by aircraft, beginning in the early evening and continuing up until 4:30 a.m., weather permitting, in areas of concern. Mosquito control professionals apply approved pesticides as an ultra-low volume (ULV) spray. ULV sprayers dispense very fine aerosol droplets that stay aloft and kill adult mosquitoes on contact.
What pesticide product is used in aerial spraying?
The pesticide used is called Anvil 10+10, a product extensively tested and used in both ground-level and aerial spraying in the U.S. to control mosquitoes. Anvil 10+10 contains two ingredients: Sumithrin and Piperonyl butoxide. Sumithrin is an ingredient similar to the natural components of the chrysanthemum flower which is also found in other pesticide products used indoors, in pet shampoos, and tick control treatments. Sumithrin is rapidly inactivated and decomposes with exposure to light and air, with a half-life of less than one day in the air and on plants. In soil, it degrades rapidly. Sumithrin has proven to be extremely effective in killing mosquitoes worldwide for more than 20 years. Piperonyl butoxide (PBO) helps Sumithrin kill mosquitoes. The product is registered by the US Environmental Protection Agency (EPA) and in Rhode Island, Connecticut, and Massachusetts for this use.
Why is this pesticide used?
Sumithrin has proven to be extremely effective in killing mosquitoes worldwide for over 20 years. The chemical properties for Anvil provide the widest margins of safety for human and environmental health when used properly by certified professionals trained to use mosquito control pesticides.
Has this pesticide been used previously in Rhode Island, and elsewhere, to control mosquitoes?
Yes. It has previously been used in Rhode Island in 2019 and specifically in Westerly in 1996. It is currently being used in Massachusetts; it was also used in Massachusetts in 2006, 2010, and 2012. Many other states, including New York, New Jersey, Illinois, Delaware, North Carolina, Arkansas, Florida, Alabama, Louisiana, Texas, regularly use it to control mosquitoes.
What are the environmental characteristics of this pesticide?
Sumithrin is short-lived in the environment. It breaks down rapidly with exposure to air and sunlight. In soil, it degrades rapidly. It does not dissolve easily in water and is broken down by microorganisms in streams and water bodies that receive sunlight.Thus, residues in water are unlikely.
Can these targeted ground and aerial sprays with adulticides harm insects or wildlife?
The EPA has evaluated these pesticides for their safety and has determined that they do not pose an unreasonable risk to birds or mammals, if used according to the product label directions. Anvil and other similar pesticides are toxic to land-dwelling and water-dwelling invertebrates (e.g., dragonflies, beetles) and to fish. There is less risk to fish in larger ponds than in smaller ones and the risks to large natural water bodies are minimal. However, people may want to cover small ornamental fish ponds in their yard during the night of spraying. These fishponds can be uncovered in the morning after spraying has been completed.
Is there a risk to drinking water sources?
No. Aerial spraying is not expected to have any impacts on surface water or drinking water Surface drinking water sources are mapped and aerial spraying will not occur over these water supply reservoirs. Also, the product is rapidly inactivated and decomposes in sunlight and air, does not dissolve easily in water, and is broken down by microorganisms in streams and water bodies that receive sunlight. Therefore, residues in water would not be expected. Because of these characteristics and the fact that spraying does not occur over drinking water supply reservoirs, exposure through drinking water is not expected.
What's done to minimize environmental impacts?
- Anvil is applied at very low concentrations to control mosquitoes.
- Spraying takes place at night, when bees are typically in their hives.
- Spraying only takes place during calm periods, with winds less than 10 MPH. This helps prevent the pesticide from drifting beyond targeted areas.
- Spraying does not occur over fish hatcheries, certified organic farms, surface drinking water supplies, and other open water bodies and coastal areas.