Understanding the Life Cycle of the Mosquito

The life cycle of the mosquito is fairly straightforward, having only four stages – egg, larva, pupa and adult.

Mosquitoes reproduce by laying eggs, usually in areas of standard water.  They may lay eggs individually, as the Anopheles and Aedes genera do, or they may lay eggs close together so that the sticky eggs form a raft of 100 eggs or more, as Culex and Culiseta mosquitoes do.  Additionally, the Aedes female lays her eggs on damp soil, where they will await rising flood waters before hatching.  Most mosquitoes lay their eggs at night and adult females can lay eggs about every three days.  In 48 hours, most eggs will hatch to reveal the larva inside.

During the larval stage, the mosquitoes will grow and molt their skin, becoming larger with each molting.  The larvae live in water, but come to the surface to breathe, using a siphon tube to hang from the water’s surface and to breathe through.  To grow, they eat organic material and micro-organisms in the water.  When the larva molt for the fourth time, the mosquitoes enter the pupal stage.  Mosquito larvae are frequently called wigglers or wrigglers.  The length of this stage depends primarily on the water temperature – typically, it will vary from one to two weeks.

During the pupal – or tumbler – stage, the mosquito rests.  In about two days, the pupae will split its skin and emerge as an adult.  During this stage, the pupae doesn’t eat, instead saving it’s strength for its third and final transformation.

The final stage of life for the mosquito is the adult phase.  The mosquito will be moist when it emerges from its pupal skin and will spend some time sitting on the surface of the water.  During this time, it will spread its wings so that they can dry and all of its various parts will harden.

If you’ve ever been bitten by a mosquito, it was a female.  Only the females bite because they need the blood to help them produce their eggs.  Males prefer to take their meals by sipping the nectar of flowers.  The most aggressive biters are from the Aedes and Culex genera.  And although Aedes mosquitoes usually don’t enter the house, Culex mosquitoes have no such qualms.

How quickly the entire life cycle of an individual mosquito is accomplished depends on a number of factors, including the particular species and environmental circumstances.  Heat plays an important role, with higher temperatures leading to less time spent in each of the first three stages.

In addition, there are a number of different ways to thwart the mosquito life cycle if you’re attempting to get rid of mosquitoes.  The best methods attack the eggs and larva and don’t allow the insects to mature and reproduce.  It also helps to reduce potential mosquito breeding sites at your home or office.  If there’s standing water anywhere on or near your property, remove it or see that it’s treated with the necessary chemicals to kill any mosquito eggs that are hanging around.

Get Familiar with the Different Types of Mosquitoes

Worldwide, there are more than 2,700 species of mosquitoes.  Rather than trying to learn how to differentiate among all these different species, it’s better to focus on the three genera that cause the most problems for humans.

The first genus to look at is the Aedes mosquitoes.  Because they need flood waters for their eggs to hatch, these mosquitoes are often called floodwater mosquitoes.  They have pointed abdomens and are capable of traveling considerable distances from their breeding sites – in fact, these strong fliers have been known to fly up to 75 miles.  Their “prey” of choice is mammals, and they have a particular fondness for humans.  The mosquito that causes yellow fever, Aedes aegypti, belongs to this genus, as does the Asian tiger mosquito, Aedes albopictus.

As humans have moved throughout the world, they’ve brought the Aedes mosquito with them – it can now be found on every continent, except Antarctica.  In fact, the most invasive mosquito in the world is the Asian tiger mosquito.  Not only do Aedes mosquitoes carry yellow fever, they also carry dengue fever, as well as human lymphatic filariasis.

The next genus is the Anopheles mosquito.  You’ll find these mosquitoes breeding in clean fresh water, such as lakes, although they can live in both fresh and salt water.  Different species of this genus have differing preferences as to plant life and shade.  Their abdomens resemble those of the Aedes mosquito, and these small mosquitoes have black and white stripes on their legs and body.  The mosquito that spreads malaria to humans, the Anopheles quadrimaculatus, is part of this genus.  The mosquito that transmits the most deadly form of malaria, Plasmodium falciparum, is the Anoepheles gambiae mosquito.

In standing water, you’ll find members of the genus Culex.  Unlike the previous two classes, these mosquitoes have blunt tips on their abdomens.  Although the bite of the Culex mosquito is painful, most generally prefer to bite birds rather than humans.  Their lives are short, lasting only a few weeks each summer and they don’t fly well, leading to their preference to stay put in standing water.  Culex pipiens – or the northern house mosquito – is a part of this genus.  A number of diseases are spread by the genus Culex, including filariasis, avian malaria, West Nile Virus, Japanese encephalitis and St. Louis encephalitis.

One key difference among the three genera is the type of water they need for breeding. The Aedes mosquito needs flood water, while the Anopheles mosquito needs oxygenated water that’s relatively still, like a pond.  The water can’t be moving too much, but it must be “alive,” with plants and animals that produce oxygen.  The Culex mosquito is the one you’ll find in bits of water in discarded tires or in the drip tray of the plant you’ve watered too much.  They need stagnant water that isn’t “alive” and contains no algae, plants or animals to keep the water oxygenated in order to thrive.

As our world changes, so too do the habitats of mosquitoes.  One cause for concern is that many winters no longer have cold enough temperatures that are sufficiently sustained to kill off the adult population of the previous year.  In addition, Aedes mosquitoes are moving north as they adapt to cooler temperatures and some of their eggs can even survive despite temperatures that are below freezing.  As the climate continues to warm, this could lead to a boom in future mosquito populations and a corresponding rise in mosquito-borne diseases.