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Mosquito Biology

Mosquito Control Program

Understanding the mosquito life cycle helps explain why standing water is the focus of mosquito control.

Mosquitoes need water for their early life stages. Reducing standing water around homes, farms, businesses, and public areas is one of the most effective ways to reduce mosquito problems in Flathead County.

Why Water Matters

Mosquito eggs, larvae, and pupae are tied to water. Even small containers, low spots, or stagnant water can support mosquito development.

Not Every Small Fly Is a Mosquito

Crane flies, midges, and gnats are often mistaken for mosquitoes. Some are nuisance insects, but they do not all bite people or spread disease.

The Mosquito Life Cycle

Mosquitoes go through four life stages: egg, larva, pupa, and adult. The larval and pupal stages are aquatic, which means they happen in water.

  1. Egg Female mosquitoes lay eggs on or near water. Some eggs hatch within days, while others can remain dormant until flooding or wet conditions return.
  2. Larva Larvae live in water and feed on tiny organisms near the surface. Many mosquito larvae breathe through an air tube and may swim in an “S” motion when disturbed.
  3. Pupa Pupae also live in water. They do not feed, but they are active and can tumble downward when disturbed. This stage is short before the adult mosquito emerges.
  4. Adult Adult mosquitoes emerge from the water. Male mosquitoes feed on plant nectar. Female mosquitoes also feed on nectar, but many species need a blood meal to produce eggs.

Montana Mosquitoes of Concern

In Montana, floodwater mosquitoes such as Aedes vexans are often responsible for severe outdoor nuisance biting. Culex tarsalis is also important because it can play a role in spreading West Nile virus.

These mosquitoes use water differently, but both show why habitat reduction and surveillance are important parts of mosquito control.

What Attracts Mosquitoes?

Standing Water

Water is required for mosquito development. Buckets, tires, bird baths, low areas, clogged gutters, stock tanks, and other water-holding places may produce mosquitoes.

People and Animals

Female mosquitoes can locate hosts by sensing carbon dioxide, body heat, and other chemical signals. This is one reason mosquitoes may be more noticeable when people gather outdoors.

Turn Biology Into Prevention

Because mosquitoes need water to develop, the most useful prevention step is to remove, drain, cover, or refresh water-holding items around your property.

Learn How to Control Mosquitoes Learn About Mosquito-Borne Diseases

Page Last Updated: May 12, 2026