Michael Morrison, Entomologist

Municipal Pest Management Services

York, ME

For many years, Portsmouth, New Hampshire was the northernmost outpost of community mosquito control along the east coast. In 1994, a mosquito control program in Maine was started at Gerrish Island in Kittery. I am presenting a history of mosquito control in Maine based upon conversations with various communities, the Maine Board of Pesticides Control, the Maine Department of Environmental Protection (MDEP), and my personal experiences.

Maine has a three thousand seven hundred mile coastline with sixteen thousand five hundred fifty- five acres of saltmarsh. Although the coastline is predominantly rocky, there are extensive areas of riverine and estuarine ecosystems. The most common wetland type is red maple swamp. The most common anthropophilic mosquito species are two saltmarsh mosquitos (Aedes cantator Coquillett and Aedes sollicitans Walker); snowmelt Aedes spp.(vernal and red maple swamps); Aedes vexans Meigen; and Coquillettidia perturbans Walker.

The earliest evidence of mosquito control in Maine is from the southern coastal town of Wells. The Wells Chamber of Commerce started a dragonfly nymph mosquito control program in 1975. Nymphs were imported from a Massachusetts biological supply company. Residents purchased the nymphs at the Chamber offices and were instructed to place them in waters adjoining their properties. The nymph program became a huge public relations attraction with articles appearing in several national magazines. Inquiries were received from all over the world. The nymph program is still in existence and is advertised each spring. I wrote the Chamber in 1986 regarding the nymph program. The response I received stated that scientifically there is no way to measure the results and that residents are very vocal in support for the nymph program. The York County Coast Star (newspaper) stated on April 9, 1986 that there has been many doubts raised over the years about the effectiveness of the nymph program, but residents and others who religiously order the nymphs are expected to remain loyal and reorder more. The newspaper article stated that the Chamber has been investigating the possible use of BTI, but in the meantime are going to stay with the nymphs.

Vectobac G, a BTI insecticide, was tested in Georgetown (mid coastal Maine) in the mid 1980's. When testing was completed, the town funded a BTI program with Vectobac to continue controlling three thousand acres of saltmarsh. A helicopter was equipped with a granular applicator and hand operated granular applicators were also utilized. The program did not last long for reasons I could not identify.

In 1990 I was invited by the City of Portland to investigate a possible mosquito control program on Cliff Island. Portland has an archipelago in Casco Bay. The islands are part of Portland and receive services from the city. Cliff Island is a seasonal vacation spot with three hundred permanent residents. I visited the island via a World War II landing craft that provides garbage removal for all the islands. Cliff Island is ten miles from the city and several miles from the nearest island. The island has a granite ridge about one mile long and a quarter of a mile wide. A lowland area extends from the ridge and has a nine acre cattail marsh and a fifteen acre abandoned cranberry bog. The cattail marsh is susceptible to saltwater flooding during storm tides. Aedes cantator and Aedes vexans have been collected from the cattail marsh. Aedes canadensis, Aedes excrucians, Aedes communis, and Aedes abserratus have been collected from vernal pools. I revisited the island in 1991 and presented a mosquito control program. My visit was well received and interest in BTI was strong. I have not been able to pursue the Cliff Island program but I plan to in 1995. Other islands have shown interest.

In 1993 1 was approached by the Gerrish Island (Homeowners) Association of Kittery, Maine. Their mosquito problem is legendary. The island is two miles long by two miles wide. The saltmarsh is flooded by tidal waters from Chauncey Creek. A seawall prevents direct flooding from the Atlantic Ocean. The saltmarsh was grid ditched but the system has failed. The interior of the island has a twenty acre red maple swamp and a seven acre shrub swamp. There are numerous vernal pools in the spring. I have collected mosquito larvae from Gerrish Island between 1990 and 1993. 1 discovered that saltmarsh mosquitos (Aedes cantator and Aedes sollicitans) and freshwater mosquitoes (snowmelt Aedes spp. and Aedes vexans) are the predominant pests during each season.

The licensing process for a mosquito control program at Gerrish Island began in October of 1993. Funding was secured from the Gerrish Island Association and local property owners were notified for access permission. The license application supplied by the Maine Department of Environmental Protection (MDEP) required detailed information on target mosquito species and wetland areas to be larvicided. There had been no mosquito control license issued by the MDEP for ten years. The license is called a Wastewater Discharge License and is sought by wastewater treatment plants and paper mills, also. A simplified application was designed by the MDEP since the previous application had many conditions not related to mosquito control. I was told by the MDEP that the most important part of the application was to describe the need for using a pesticide, economic considerations and the impact upon non-target species. The application fee was $195.00 and the license is good for five years.

The license was issued by the MDEP in April of 1994 after six months of communications between myself and MDEP biologists. MDEP was very helpful and careful in assuring the license application was accurate. MDEP listed "findings of facts" regarding the license. They stated that the discharge (BTI application) would not lower existing water quality; will not have a significant impact upon non-target organisms, existing wildlife, or plant uses; and will not result in significant degradation of the human uses of the receiving water. MDEP further stated that the discharge is necessary to allow citizens of Gerrish Island to make full social and economic use of their properties and that there are no practical or economically feasible alternatives to spraying for mosquito control.

In summary, the MDEP is very cautious in approving mosquito control license applications. Conventional larvicides would most likely not be approved for discharge licenses. BTI is approved by MDEP biologists but only after close scrutiny. The Gerrish Island discharge license has proven to be a time consuming ordeal. Future discharge licenses should be much easier now that I know exactly what information is required.