David L. Deen | River Currents: Mosquitoes serve a purpose
If one were to offer that there was something good about mosquitoes, now would be the time of year to do so since they are not likely to be annoying anyone right now and annoy they do, but like all living things mosquitoes serve valuable functions in the ecosystem.
Around the world, there are 3,500 species of mosquitoes. Of those 3,500, there are two major genus of mosquitoes found in our watershed. One is of the genus Culex that lay their eggs on the surface of water. In particular, the species here is Culex pipiens the common house mosquito or northern house mosquito. The other major genus here is Aedes that deposit their eggs at the base of vegetation near but above the water line in anything that holds water including old tires, tree holes, and even pitcher plants.
The word mosquito means little insect in Spanish but step up the taxonomic ladder one rung to the genus level and the Culex genus name means gnat or midge while the other main genus found in our watershed, Aedes means unpleasant or odious. Studies suggest that the two main species found here diverged from each other 226 million years ago meaning mosquitoes have always been with us.
Mosquitoes live up to 30 days and fly at a humble 1.5 miles per hour and strain flying into a wind much above that speed. They fly by beating their wings about 600 times per second creating that unique mosquito whine. Mosquitoes with a good tail wind can travel 75 to 100 miles, whining maddeningly all the way.
Mosquitoes go through four life stages: egg, larva, pupa, and adult. The first three stages require water for success. The time it takes mosquitoes to go from an egg to an adult varies depending on the species and the ambient temperature. Some mosquitoes develop from an egg to adult in less than a week. There are usually the same numbers of females as males that hatch at any given time. Females only need to mate once storing the sperm for use over their lifetime.
All adult mosquito bodies have three sections: head, thorax, and abdomen. The head acquires information and identifies feeding opportunities through the eyes and a pair of long segmented antennae. The antennae detect odors, especially carbon dioxide exhaled by mammals and then there is the elongated jutting proboscis used for feeding on nectar in males and females of some species and blood in females of most species. The thorax holds three pairs of legs and two pairs of wings. The larger wing pair the mosquito uses for flight; the other smaller pair is for balance while flying.
The abdomen digests food and in addition, in the female this is where eggs develop. Since females need animal blood for the eggs to mature, the segmented abdomen expands when a female ingests it. As a necessary source of protein for the eggs, females digest the blood over two or more days before egg laying. After laying eggs, females will begin searching for another blood meal.
The world history of mosquito spread diseases is long, deadly, and complicated and now due to climate change, the life cycle of mosquitoes has shortened, their geographic distribution has expanded, and disease infection rates have increased. This is not a good situation since mosquitoes are carriers of diseases, especially viral diseases. Some of those diseases present in our watershed are West Nile Virus, Eastern Equine encephalitis, Saint Louis encephalitis, dog heartworm, and La Crosse encephalitis. On the world stage, mosquitoes are the main carrier of malaria, yellow fever, and dengue but fortunately, we do not yet find these diseases here in the North Country.
What else besides biting us, making irritating sounds, and serving as a means to spread disease could mosquitoes offer that makes them valuable to life. It's all in the numbers.
When mosquitoes breed, they do so in incredible numbers and anything in nature that reproduces in quantity becomes food for other species. Mosquitoes in the egg, larval and pupa stages serve as food for frogs, salamander, lizards, toads, larval and pupa forms of other aquatic insects, and fish. The adult life stage feeds spiders, birds, bats, and mosquito hawks better known as dragonflies. Since most adult male mosquitoes are nectar drinkers, they actually can serve as pollinators for those flowers at which they obtain nectar.
In the wild, an important value of the mosquito is animal population control. Female mosquitoes convey disease from one animal to another and by transmitting diseases, mosquitoes are responsible for culling weaker animals out of herds helping prevent over population.
Next time, before you smack that mosquito that has alighted on your arm, neck or other exposed skin, you might think briefly about the positive roles this pest plays but go ahead and swat it. We are not likely ever to run out of mosquitoes!
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