Mosquito Biology:  




Mosquito control starts in the swamps, marshes, seepage ponds, and any other area that holds shallow stagnant water.  To understand why water is critical to mosquitoes, one must understand the mosquito life cycle.


Mosquitoes have four distinct stages in their life cycle: egg, larva, pupa, and adult.   


Depending on the species of mosquito, eggs are laid either singly or attached to each other in groups of 50-200 eggs.  When the eggs are joined together, they are called an egg raft.  Most mosquitoes lay their eggs directly on the water surface where they hatch into larvae a couple days later.  There are also some mosquitoes that lay their eggs on the ground next to the water.  When the water rises from increased irrigation, snow melt, etc., the eggs hatch and the larvae emerge.  Regardless of the mosquito species, all larvae require water to survive.

A mosquito larva, as seen through a microscope.  
Photo credit: Christina Johnson, GCMCD

Once the larvae emerge from the egg they begin filter feeding.  At this point in their life cycle they feed only on microorganisms and small organic material in the water.  The larvae breathe through a siphon tube that penetrates the water surface.  During their larval stage, the mosquitoes will shed their skin and molt four times before changing to the pupal stage of their life cycle.

Mosquito pupae resting just below the surface of the water.

The pupal stage is where metmorphasis occurs, creating the adult mosquito.   During the pupal stage they are no longer feeding as they have ingested enough nutrients to make the transition into an adult.  This phase of the life cycle is similar to the cocoon of a butterfly although the mosquito pupa is fully active and mobile.  Like the larval stage, the pupal stage of a mosquito is entirely aquatic, and the mosquito will parish if it is removed from water.



The adult stage the portion of the life cycle most people associate with mosquitoes.  This is also the only stage in their life cycle which they are not fully aquatic, and the only stage in which they take a blood meal.  After emerging from the pupal casing, the newly hatched adult will rest on top of the water to dry its wings and body.  Once dried, the mosquito is capable of flight.