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Mosquitoes

Everyone has seen or been "bitten" by a mosquito. Mosquitoes are notorious for invading campsites, hiking trails, lakes, and even backyards. Although many people consider mosquitoes a nuisance, mosquitoes can also be very dangerous as they carry and transmit diseases. Insect repellents are used to prevent the spread of disease as well as prevent painful bites. Mosquitoes have been around for over 30 million years and are responsible for more human deaths than any other insect through disease and infection transferring. While mosquitoes have always been thought to be relatively harmless in North America, recent incidents of the West Nile Virus and certain types of Encephalitis have forced North Americans to take a much more liberal approach to mosquito reduction.

Mosquitoes have multiple ways of detecting prey - they have chemical sensors which sense carbon dioxide (exhaled by animals and humans) from up to 100 ft away. Chemicals in secretions of sweat also attract mosquitoes. Although mosquitoes do not have excellent vision, they can detect movement, especially in humans with clothes that contrast their surroundings (a white shirt while camping for example). Mosquitoes can also detect heat, making it easier for them to hone in on warm blooded animals.

Types of Mosquitoes

There are more than 2700 species of mosquitoes worldwide and 13 main types (or genera) of mosquitoes found in the United States, most of them belonging to these three:

Aedes: Mosquitoes with a painful bite that reside almost exclusively in floodwater areas. These mosquitoes mainly feed at dusk or dawn and can travel distances of up to 75 miles from their breeding area. Included species are the yellow-fever mosquito and the Asian tiger mosquito.

Anopheles: These mosquitoes live in permanent fresh water sites. Their bite is less painful, and they too mainly feed at dusk and dawn. Included in this species is the common malaria mosquito that can spread malaria to humans.

Culex: The breeding ground for these mosquitoes is usually small pools of standing water. They do not fly far from their breeding grounds as they are relatively weak fliers. The northern house mosquito is one of the species in this genus. While their bite is painful, they tend to attack birds and small mammals instead of humans. They too commonly feed at dusk or dawn.

Feeding

Contrary to the above text, mosquitoes do not actually ‘bite’. The female mosquito sucks blood (hematophagy) to acquire the necessary blood meal proteins for breeding. Only the female sucks blood and does not need blood to survive - only to reproduce. The female has a protruding needle-like proboscis extending from her head which she inserts into mammals and discharges a small amount of saliva. In some species the saliva will numb the nerves under the skin so that the victim does not feel the ‘bite’. Also present in the saliva are anticoagulant proteins which stop the blood from clotting at the wound - allowing her to feed until she is full which she does by sucking blood and storing it in her abdomen. Once the mosquito is done feeding, it flies away, leaving some saliva under the skin - the saliva induces an immune response from your body and the area around the bite (the ‘wheal’) swells and itches. Mosquitoes feed on many types of mammals including birds, horses, squirrels, birds and humans.

Breeding and Life Cycle

Egg

The female mosquito will lay a single egg or a ‘raft’ of eggs which float on the surface of water. Some eggs can survive the entire winter and hatch the next spring.

Larva

The mosquito life cycle starts with the female mosquito laying her eggs on a water surface or in an area where water will eventually flood. When the larva is hatched, it lives exclusively in water (on the surface) and looks like a small thin maggot like insect. It breathes through a small tube or siphon and sheds its skin (molts) several times. Larvae grow to approximately 1-2cm in length depending on species.

Pupa

The larvae then changes into an aquatic pupa, a curved larva with a large bulbous area at the top. The pupa lives just under the surface of the water for about one to four days, breathing through two small tubes. They do not eat at this time. Near the end of the pupal stage, the pupa encases itself (much like butterflies) and transforms itself into an adult mosquito.

Adult

Once the adult mosquito breaks its pupal case, it still cannot fly. The mosquito crawls to a dry place on land and waits for its wings to dry and its new exoskeleton hardens. Once dry, the mosquito can fly. Male mosquitoes immediately find a female mosquito and mate. Afterwards, they will feed (male mosquitoes feed on plant nectar) and die a few days later. Female mosquitoes will mate and then immediately feed on animal or human blood - enabling her to lay her eggs. She will continue to feed and lay eggs for her entire life - which, depending on species, can last from days to weeks and sometimes longer through the winter.

Diseases

Besides the obvious annoyance of mosquitoes, mosquitoes and mosquito bites can be quite dangerous. In fact, mosquitoes are responsible for killing millions of humans per year by way of transmitting diseases. Malaria, for example, is transmitted by mosquitoes and kills over one million people a year. Serious global efforts are being made to combat mosquitoes and the spread of malaria, such as the Buzz Away Against Malaria campaign which distributes nets to the hardest hit regions in Africa. Other diseases carried and transmitted by mosquitoes are Yellow Fever, Dengue Fever, Filariasis (causing elephantitis), and West Nile Virus to name a few.

Mosquito Protection and Repellents

To protect yourself from mosquitoes, wear clothing that covers most of your body. Keep in mind, mosquitoes can ‘bite’ through thin cloth. Using a mosquito net when you sleep in areas with large mosquito populations is a good idea. For long term mosquito reduction (at your home for example), try to eradicate any standing water such as rain water collected in buckets , watering cans, or any other object that can collect dew or water. There are many mosquito repellents on the market today. Unfortunately, most of them contain harmful chemicals, the most common being DEET (NN-diethyl-meta-toluamide). Although DEET does work to ‘confuse’ the mosquitoes receptors, there are more and more studies indicating that DEET can cause nausea, tremors or even death in small children. Another chemical used for some repellents is Permethrin, although this is used for clothing only as it is a neurotoxin.

Natural repellents are the smartest choice for people who do not want to use potentially harmful chemicals on their body. Natural repellents can work as well as chemical repellents and are completely safe. An example of a natural mosquito repellent is Buzz Away, which contains all natural ingredients including soy bean and geranium oils. citronella, cedarwood, lemongrass, peppermint and eucalyptus oils, and contains no preservatives, toxins or petrochemicals, Studies with Buzz Away at the University of Guelph and by the USDA show that Buzz Away is equally effective as DEET based repellents. Most natural repellents are effective for up to 2 hours, but Buzz Away Extreme is effective for 4 to 8 hours per application.

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