Mosquito Biology

Diet & Life Cycle

All mosquitoes require water to complete their life cycles, which includes four stages of development: eggs, larvae, pupae, and adults.

Click on each stage of the mosquito life cycle to learn more.

Did you know?
Only female mosquitoes bite and take blood meals.

Different groups of mosquitoes have a distinct preference for the habitat they choose to lay their eggs in. Some mosquitoes lay their eggs on the surface of standing water, while others lay their eggs on soil that will later be flooded.

Some groups of mosquitoes, such as Culex and Culiseta, lay batches of 100-300 eggs that are glued together in rafts and deposited on the surface of water. In comparison, Aedes and Anopheles lay each individual egg separately. Anopheles lay their individual eggs on the surface of standing water, whereas Aedes lay their individual eggs on soil throughout a landscape that will later flood. 

Culex, Culiseta, and Anopheles eggs hatch after approximately two days of coming in contact with water. Aedes mosquitoes have desiccant-resistant and cold-tolerant eggs that can overwinter or lie dormant for several months or even years before hatching. Aedes eggs are also adapted to hatch in waves, meaning some will hatch during the first flooding cycle of a season, while others can go through multiple flooding events before hatching. Because Aedes mosquitoes lay their eggs throughout the landscape in soil that will be flooded, and their eggs can survive for years in the soil, they are the major pestiferous group of mosquitoes in Teton County. Due to our large wetlands, floodplains, and irrigated pastures, the Aedes group of mosquitoes can breed in the tens of thousands in a single summer here.

Once the eggs hatch, the larvae begin eating voraciously. They are filter feeders and grazers, eating microorganisms and organic matter in the water. Although they live in water, mosquito larvae must breathe air to survive. Most mosquito larvae have an appendage called a siphon. The surface tension of the water allows the siphons to open, permitting the larvae to breathe at the water’s surface. Anopheles mosquitoes lack a siphon. They breathe at the water surface through breathing holes along the body called spiracles. 

In order to accommodate growth, the larvae must molt their skin, or exoskeletons. Mosquito larvae molt four times before turning into pupae. Each of the larval stages between molts are called “instars.” In the summer months, larval development usually takes 4-7 days depending on the species and the temperature. The warmer the temperature, the faster the larvae develop. Some mosquito species, however, spend the winter as larvae. These mosquitoes are often referred to as snow pool mosquitoes, emerging as adults in early spring as the temperature rises and snow melts.

The last immature aquatic stage is the pupal stage. This is the metamorphosis stage, where the mosquito transforms from the aquatic larvae to the adult form. The pupal stage usually takes about two days to complete. Like the larvae, how quickly this stage is completed is temperature dependent.

Pupae do not feed, but they can move. Pupae are lighter than water, so when disturbed, they will dive down from the surface of the water in a tumbling motion before floating back up. The pupae must also breathe air to survive. Like the larvae, they use the surface tension of water to open their breathing tubes, called trumpets, at the surface of the water to access air. When development is complete, the pupal skin splits open and the mosquito emerges as an adult.

When an adult mosquito emerges from the pupal stage, they seek out plant nectar in order to get the energy they need to fly, mate, and seek out hosts. While both the males and females feed on plant nectar, only the females take blood meals. The females require the protein in blood to develop her eggs. After a blood meal, it takes approximately 3-5 days for the female to digest the blood and for the eggs to develop. With each blood meal, a female mosquito can produce up to 300 eggs. Females can produce up to 2-4 egg batches in her lifetime depending on the species and how long she lives. 

Male mosquitoes only live for a short time after they have mated, while females can live much longer depending on the species, temperature, humidity, and season. Females can live for several weeks or even months in the case of those species that overwinter as adults. Female mosquitoes transmit diseases when they live long enough to obtain a pathogen during one blood meal, and then pass it on during subsequent blood meals. The type of hosts a female mosquito prefers is usually dependent on the species. Some may feed on only one type of host, while others may feed on a variety of hosts. 

The flight range of mosquitoes is also dependent on the species. Some species do not travel very far from their larval habitat, while others can fly great distances and have been recorded as far as 75 miles away from where they emerged. Long flight ranges are common with floodwater species, such as Aedes dorsalis, a major pestiferous species in Teton County.

Mosquito Habitats

Mosquitoes can be quite selective in which habitats they lay their eggs in, and there are numerous types of habitats they breed in. This usually varies depending on the species. Examples of diverse mosquito habitats include wetlands, storm drains, irrigated pastures, water treatment ponds, snow or rain pools, and containers such as buckets, horse troughs, and tree holes. 

All mosquito breeding habitats generally fall into three categories: floodwater, semi-permanent / permanent, and container. In Teton County, the major pestiferous mosquito-producing habitats are floodwater and semi-permanent. Semi-permanent / permanent habitats can also be important in Teton County for medically significant species such as Culex tarsalis, Wyoming’s major West Nile virus vector mosquito.

Breeding Habitats

Floodwater mosquito habitats, also referred to as transient habitats, are those that have water on the landscape for a limited time, but long enough to support mosquito development. This can range from several days to several weeks. Examples of floodwater mosquito habitats include floodplains along stream and river banks, irrigated pastures and meadows, pooling around culverts and drainage ditches, and temporary pools created by rain, melting snow, or natural springs. 

Floodwater habitats go through wetting and drying periods, so the type of mosquito that lays eggs in these habitats must be adapted to these conditions. Many Aedes mosquitoes are associated with flood water habitats locally, and they are the most abundant and pestiferous mosquitoes in Teton County. 

Floodwater habitats are considered semi-permanent if the water stays on the landscape long enough. For example, irrigated pastures and meadows that are flooded throughout the summer are later considered semi-permanent mosquito habitats. Other groups of mosquitoes will use these habitats later in the summer, including vector Culex species. 

Semi-permanent / permanent mosquito habitats have water on the landscape for an extended period of time. Examples of semi-permanent / permanent habitats include wetlands such as freshwater swamps and marshes, storm-water catch basins, natural, ornamental, retention, and wastewater treatment ponds, and pastures and meadows that are irrigated summer long. Local groups of mosquitoes associated with semi-permanent / permanent habitats include Culex, Culiseta, and Anopheles. Eggs of these mosquitoes are not desiccant-resistant and must be laid directly on the water. Aedes mosquitoes lay their eggs throughout irrigated pastures and meadows, and will sometimes lay eggs on the soil at the edges of more permanent water bodies.

Container habitats can be either natural or artificial containers that fill with rain water and support mosquito breeding.

Natural Containers

Tree holes are an example of a natural mosquito container habitat in Teton County. Aedes sierrensis, or the Western Treehole Mosquito, utilizes tree hole habitats locally. Aedes sierrensis is a competent vector for Dog Heartworm.

Artificial Containers

Artificial containers can be any type of man-made object holding rain water that has been allowed to stagnate, including discarded tires, kayaks, boats, horse troughs, bird baths, buckets, wheelbarrows, clogged gutters, pet dishes, flower pots, etc. Containers with foul, stagnant water with decomposing organic matter, such as dead leaves or grass clippings, can be especially attractive to mosquitoes. Culex and Culiseta mosquitoes have been observed using artificial containers, including WNV vector species Culex tarsalis and Culex pipiens. 

Resting Habitats for Adult Mosquitoes

Adult mosquitoes can often be found resting on vegetation or objects near their breeding habitats, while others may travel far distances in search of mates and hosts. Adult mosquitoes seek out areas to rest during the day, away from the hot sun, dry air, and wind. Sheltered areas with favorable microclimates for adults, such as higher humidity and lower temperature, can include tall grasses, dense vegetation, hollow trees, rock crevices, caves, sheds, culverts, and others.

Some mosquito species will leave these resting places during the day to opportunistically feed if a host enters their habitat. These mosquitoes are often referred to as day biters.

In Wyoming, the tall grasses in hay fields can be a major resting habitat for adult mosquitoes. When it comes time to cut hay, the mosquitoes resting there will often flush into neighboring areas. The numbers of mosquitoes flushed during cutting can often be significant.

Local Mosquitoes

There are approximately 56 species of mosquitoes that have been recorded in Wyoming. In Teton County, 41 of those species have been documented. The groups (or genera) of mosquitoes in Teton County include Aedes, Culiseta, Anopheles, and Culex.

The bulk of mosquito species in Teton County are rare or infrequently observed. The vast majority of vector and pestiferous mosquito problems each summer are caused by just four mosquito species: Culex tarsalis, Aedes vexans, Aedes dorsalis, and Aedes idahoensis. 

Secondarily pestiferous species in Teton County include Aedes cinereus, Aedes implicatus, Aedes fitchii, Aedes increpitus, Aedes cataphylla, and Culiseta inornata.

Culex tarsalis or the Western Encephalitis Mosquito is a competent vector for multiple pathogens that can impact humans, including West Nile virus. Cx. tarsalis is an aggressive day biter and will readily enter buildings. Cx. tarsalis primarily feeds on birds, but will shift host use later in the summer to humans, horses, and cattle in agricultural areas. They are active from spring to autumn, and the adult females overwinter in sheltered areas such as caves, pipes, sheds, and garages.

Photo Credit: Joseph Berger,

Aedes vexans, or the Inland Floodwater Mosquito, is a very common mosquito globally. This species breeds in a diversity of floodwater habitats such as irrigated pastures, ditches, swamps, ephemeral pools, and river floodplains. There are multiple generations per summer. Eggs are desiccant resistant and can survive in the soil for up to three years and each female can lay hundreds of eggs in her lifetime. Ae. vexans can reach levels of significant abundance and be a major pest affecting humans and cattle in the summertime.

Photo Credit: Katja Schulz,

Aedes dorsalis, or the Summer Saltmarsh Mosquito breeds in multiple floodwater habitats, and some populations can even tolerate saltwater. Ae. dorsalis are strong fliers and can disperse far from their breeding habitats. There are multiple generations per summer. They are opportunistic feeders and will readily bite during the day if hosts are near. They feed on a variety of hosts, including humans, and are a major pest species, biting incessantly during both the day and at dusk in the summertime.

Photo Credit: Sean McCann,

Aedes spencerii idahoensis begins hatching in early spring in snow pools and floodwaters and continues to hatch throughout the summer in irrigated pastures and wetland habitats, preferring alkaline waters. Despite having just one generation per year, Ae. idahoensis can be a major pest species to both humans and livestock. They will readily bite during the day, but peak activity occurs at dusk.
Photo Credit: Carpenter, S. J. and W. J. LaCasse. 1955. Mosquitoes of North America (North of Mexico).

Mosquito Look-alikes

There are many insects that look quite similar to mosquitoes. Many of these hatch in large numbers, are attracted to lights, and can often be mistaken for a large swarm of mosquitoes.

These look-alikes are non-biting, but sometimes can be considered a nuisance in large numbers. Below are the insects most commonly mistaken for mosquitoes.

There are biting midges, or “no-see-ums”, in Wyoming. These are not usually mistaken for mosquitoes due to their very minute size.


Fungus and wood gnats are small flying insects that also resemble mosquitoes. They are often associated with damp soil in houseplants or decaying organic matter such as compost or mulch piles. They do not bite humans, but the larvae can be damaging to the roots of houseplants.

Photo Credit: Joseph Berger,

Crane Flies

Crane flies are often mistaken for giant mosquitoes, and are commonly referred to as “mosquito hawks.” It is a common misconception that crane flies eat mosquitoes, but crane fly adults are not predators. Some eat very little, sponging up plant juices occasionally, while others lack mouthparts entirely as adults. Crane flies spend the majority of their lives as larvae, and only a very short time is spent in the adult form for mating. Despite their large size, crane flies are harmless and do not bite humans.

Photo Credit: Joseph Berger,


Mayflies are quite common in Teton County, and are very important insects in a healthy river ecosystem. Unlike mosquitoes that require stagnant water, immature life stages of mayflies develop in moving water. Large hatches from the many rivers and streams in our area are common. Adults are short-lived and cannot bite, as the adults lack mouthparts.

Photo Credit: Joseph Berger,

Moth Flies 

Moth flies, also referred to as owl midges or drain flies, are small hairy flies. The larvae develop in aquatic or semi-aquatic habitats, and they can hatch off in large numbers during the summer. They get the name drain flies because they can often breed in sewers or indoors when there is a leak in a shower, bath, or laundry drain. These flies do not bite, but they can be pestiferous indoors.

Photo Credit: Whitney Cranshaw, Colorado State University,