Yes, under certain circumstances, native species such as mosquitoes are managed to decrease populations such as when a public health emergency has been declared. The localized application of larvacides and adulticides for the management of native mosquitoes is allowed but must be approved by the Director of the National Park Service in Washington. The Centers for Disease Control and the U.S. Public Health Service have not indicated that there is a significant threat human safety on Fire Island. Until there is a health risk declared by the CDC, the application of pesticides may be a greater health threat to the public than the mosquitoes. We do take numerous other steps to help prevent the spread of disease before there is a health emergency.
Benefits are in the eye of the beholder.
Everything in nature occupies an important place. From most public stand points mosquitoes don't have much use. However, mosquitoes pollinate flowers, and provide an important food source for a wide range of creatures such as fish, turtles, frogs, birds, and bats. It is also important to remember that pesticides kill almost all insects and many other organisms they contact. This includes butterflies, mites, ladybugs, and other insects that pollinate flowers, remove detritus from the ecosystem, digest feces, and all the other important functions we depend upon insects to perform in the environment.