All About Mosquitoes

We all know what mosquitoes are.  Few have escaped their sneaky attack and the resulting bite that leaves an itchy, irritated bump for several days.  They are unwanted, uninvited pests that can quickly spoil a barbeque, fishing trip, sporting event, or any other outdoor activity.  Besides being a nuisance, mosquitoes also transmit serious diseases that affect both humans and animals, such as West Nile Virus (WNV), Malaria, Eastern Equine Encephalitis (EEE), St. Louis Encephalitis (SLE), and Yellow Fever, among others.    


Mosquitoes attack humans or other animals not for food or to simply be annoying.  They do so because they need blood to produce eggs.  As this is the case, only female mosquitoes bite.  Male mosquitoes live off of nectar and other sugar sources they suck from plants.  After a female has taken a blood meal, she lays her eggs on the surface of the water either in singles or in batches, called rafts, of 100 or more.  Within a day or two, the eggs hatch into larvae (called wigglers).  While nearly invisible to the naked eye at hatching, larvae feed on various organic material in the water and complete three more molts while in the larval stage, growing larger each time.  After reaching the fourth stage (typically within four to five days), the larva molts again to become a pupa (called tumblers).  During this life stage, pupae do not feed but prepare to emerge as adults.  It is during this stage that the transformation into an adult is complete.  Within about one to two days, the pupal case splits and the adult mosquito emerges.  The adult mosquito rests on the surface of the water until its body drys and hardens.  

Females lay eggs one at a time or in "rafts" of 100 to 300 (as shown above).  Most eggs hatch within 48 hours.  Water is necessary for eggs to hatch.  If water is not available when eggs are lain, they can overwinter, surviving subzero temperature, until water becomes available.

Larvae shed (molt) their skin four times before becoming a pupa.  Most larvae have siphon tubes that they use for breathing.  They hang upside down from the water surface.

There are about 2,700 species of mosquitoes throughout the world and 176 species within the United States.  Not all mosquitoes species are created equal: some don't annoy or spread disease to humans.   However, many do. Within Summit County, we have about 13 species that are active, and two species, Culex Tarsalis and Culex Erythrothorax are known carriers of the West Nile Virus.  During the summer season, SMAD conducts regular surveillance and testing of mosquitoes within the the county to help locate areas where any mosquitoes infected with WNV may be found.

Other interesting mosquito facts:

Pupae do not feed but are mobile. They take in oxygen by attaching to the water's surface and breathing through two tubes called trumpets.

Female mosquitoes need blood to complete the development of their eggs.  When a female bites, she pierces the skin to find a blood vessel and injects saliva that contains an anticoagulant, a compound that prevents blood from clotting in her mouth parts and gut.  It is through her saliva that a female infects a human or animal with a disease such as West Nile Virus. 

For more interesting information about mosquitoes, check out the following web sites:

> American Mosquito Control Association

> Pestworld for Kids 

> Mosquito Magnet

> Mosquito Squad