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For Your Information
Division of Agriculture
Mosquito Abatement Coordination
Al Gettman, Ph.D.
URI East Farm
Mosquitoes in Rhode Island
Rhode Island is home to 46 different mosquito species!
While both male and female mosquitoes need nectar for sustenance, only the female requires a blood meal, which is needed for egg production. Several days after ingesting the meal, a batch of up to 250 eggs is laid. Some species lay egg "rafts" on the water surface which hatch in two days. Other species deposit eggs above the water surface, around the edges of depressions. These eggs can remain viable for months and hatch when flooded.
The next stage after the egg hatches is the larval stage. During this stage, the larvae "wiggle" in the water and will go through four developmental stages where they will shed their skin or "molt". They filter-feed and breathe at the surface. The larval stages last from five days to several months, depending on several factors. Larvae then become the non-feeding pupal stage, which lasts for several days before adults emerge.
Immature stages can occur in a variety of aquatic habitats including salt marshes, freshwater swamps, woodland pools, retention ponds, abandoned swimming pools and artificial containers. For this reason, it is important that homeowners do not permit stagnant water to collect in backyard containers, as several important disease-transmitting species are readily produced in these habitats.
Immature stages do not occur in flowing water, and are generally absent from permanent bodies of water, which tend to support a variety of predatory creatures. Finally, the immature stages of many species only occur in particular habitats. For example, species that occur in salt marshes do not occur in backyard artificial containers, and vice-versa.
For more information, visit the following sites: Mosquito-Borne Diseases in RI
Eastern Equine Encephalitis (EEE) and West Nile Virus (WNV) are the two human diseases transmitted by mosquitoes in RI. Both are maintained in bird populations in nature. Mosquito species that bite both birds and mammals acquire these diseases from birds and can then transmit them to humans. EEE has a very high human mortality, but fortunately is very rare. WNV has a very low human mortality, but has become prevalent in both rural and urban environments since its establishment in RI in 2000.
The most effective way to reduce the risk of acquiring EEE and WNV is to reduce exposure to mosquito bites. Mosquito biting is more prevalent at dawn and dusk, in the shade and at temperatures above 55 degrees. Wearing protective clothing and using repellents containing DEET are effective ways for reducing risk. Finally, it is important to maintain screens and prevent stagnant water from collecting in artificial containers around the home.
For more information, visit the following sites: Salt Marsh Water Management
Narragansett Bay and the islands are fringed by some 3,600 acres of salt marsh which provide many valuable functions. Unfortunately, two species of mosquitoes can be produced in tremendous numbers from this habitat. Large "broods" of adults can occur following the highest monthly tides, which hatch eggs that were deposited in the higher elevations of the marsh. Water management projects involve altering the water regime to reduce stagnant pools, and to enhance predation of larvae by fish.
Many acres of RI salt marshes have been degraded due to human intervention. Roadways, dikes, undersized culverts and excess runoff from adjacent upland development have altered the tidal regime and soil salinity, such that undesirable invasive plant species thrive. The MAC Office partners with other agencies and organizations on projects aimed at restoring salt marshes utilizing water management and other techniques.
For more information, visit the following sites: