Mosquitoes are blood-feeding ectoparasites of people and animals. There are about 100 trillion mosquitoes with at least 3,450 species in the world. Mosquito-borne diseases infect about 700 million people each year and kill 3 million. Of all of the harmful creatures on earth, the mosquito probably presents the greatest threat to mankind.
There are about 200 different species of mosquitoes in North America, each of which lives in a specific habitat and exhibits unique behaviors. Despite these differences, all mosquitoes share some common traits such as a four stage life cycle.
Not only are mosquitoes annoying, their bites can be the transmitters of malaria, yellow fever, Dengue fever, and several forms of encephalitis including the newest concern, West Nile Virus. Not only are they a threat to humans, but mosquitoes also transmit several diseases that both dogs and horses are susceptible to. These include heart worm in dogs and strains of encephalitis including West Nile Virus in horses.
The U.S and Canada spend about 150 million dollars each year in an effort to control mosquitoes. This does not include money spent by individuals on repellants, insecticide, poisons, screens and other products.
Mosquitoes have been around for over 30 million years. Over that time they have evolved a variety of sensors designed to track their prey, including:
- Chemical Sensors - mosquitoes can sense carbon dioxide and lactic acid up to 100 feet (36 meters) away. Mammals emit these gases as part of the breathing process. Sweat, and the chemicals it contains also seems to be an attractant. (People who sweat heavily seem to get more mosquito bites).
- Visual Sensors - Mosquitoes seem to hone in on clothing that contrasts with the wearers background, especially if there is movement. The strategy is that anything moving is alive, and therefore full of blood.
- Heat Sensors - Mosquitoes can detect heat, and as a result, warm blooded mammals and birds.
GeneraMost mosquitoes belong to one of three genera:
- Aedes - Sometimes called "floodwater mosquitoes" because they rely on flooding for their eggs to hatch. They include species such as the yellow-fever mosquito and the Asian tiger mosquito. They are strong fliers capable of traveling great distances from their breeding sites (up to 75 miles/121 kms). They persistently bite mainly humans, mainly at dawn or in the early evening. Their bites are painful.
- Anopheles - These breed in bodies of permanent fresh water. They include several species such as the common malaria mosquito that can spread malaria to humans.
- Culex - These tend to breed in quiet standing water. They include species such as the northern house mosquito. They are weak fliers and live for only a few weeks during the summer months. They prefer to bite birds over humans. They attack at dawn or after dusk with a painful bite.
The Difference Between Male and Female Mosquitoes
What makes mosquitoes different from all other flies is the presence of a long piercing mouthpart called a proboscus. Male mosquitoes differ from the female gender in that they have feathery antennae and smaller mouthparts.
The most important difference between male and female however lies in what the proboscus is used for. The adult male uses its mouthparts to feed on flower nectar and juices. The female mouthparts however are used for piercing, cutting and sucking. Only the female mosquito sucks blood, which she needs to produce eggs.
Life Cycle & Breeding
Like all insects, mosquitoes hatch from eggs and go through several stages in their life cycles before becoming adults. The females lay their eggs in water and the larval and pupal stages live entirely in water. When the pupa change into adults they leave the water and become free-flying land insects. Life cycles vary from one to several weeks depending on species.
With the exception of Aedes mosquitoes, all species lay their eggs on the surface of standing water. Eggs can be laid singly, or as a group forming a raft formation. Aedes mosquitoes lay their eggs above water in protected areas that eventually flood. Most eggs can survive the winter and will hatch in the spring, but they can lie dormant for up to 7 years.
Mosquito eggs hatch into larva or "wigglers", which live on the surface of water, and except for the Anopheles larvae, breathe through an air tube or siphon. Anopheles breath directly through a hole in their abdomens. Initially the larvae filter organic material through their mouth parts, but can turn cannibalistic over the 4 - 10 day development period, which is determined by species and water temperature. The larvae will shed their skin or "molt" several times over this period. This is the mosquitoes' most vulnerable period as they are concentrated in small areas. They are however capable of swimming, and dive down from the surface when disturbed.
After the fourth "molt", the larvae change into pupae or "tumblers", which live in the water anywhere from one to ten days depending on water temperature and species. The pupa has a large combined head and thorax, and a slender abdomen giving it a comma shape. The pupa swims actively and breathes through two small tubes, or "trumpets".
Small and fragile, two winged with long, slender legs, adult mosquitoes are capable of flying from one to several miles, and may fly up to 300 miles in their lifetimes. Some adults will not go more than 500 feet from their larval habitat, while some can cover 6-8 miles with the help of the wind. Adult flying mosquitoes often rest in tall grass and shrubbery during non-biting periods.
The female flies into a swarm of males and mating takes place almost immediately in midair. Mating takes from 4 - 40 seconds and some couples stay together for as much as an hour.
|Mosquito Quick Facts|