Are mosquitoes important for anything or just pests?

Question Answered by Marilyn Case, Health Physicist, INL ESER Program

Mosquitoes are pests whose only purpose seems to be to torment humans and animals with their vicious, blood-sucking bites.  However, as annoying as mosquitoes are, they do play an important role in the food web on the planet.  During the course of their lifespan, mosquito eggs, larvae, pupae, and adults are important sources of food for many animals.  If mosquitoes were to disappear completely from this earth, animals that eat them might have trouble getting enough food. 

For example, in the Everglades, mosquito larvae are consumed by “mosquito fish” (as many as 200+ per day per fish), which in turn are eaten by fish and eventually alligators.  Adult mosquitoes typically have life spans of one month.  During that time, dragonflies, birds, amphibians and reptiles eagerly pursue them as tasty prey.  Bats can eat thousands of mosquitoes in one night. Male mosquitoes that survive, function as pollinators for various plants, while females will hunt for a bellyful of blood that will allow her eggs to develop.  Should you be the unwilling donor in this process, you become part of the food web! 

Although mosquitoes are a vital link in some ecosystems, they can also be extremely harmful to humans and animals because they can transmit diseases such as malaria, encephalitis and, closer to home, the West Nile virus.  To avoid infection, steer clear of mosquito-infested areas at dusk and dawn, the prime biting hours and reduce mosquito numbers around the home by draining pools of standing water. However, even if you are bit, human infections resulting from the West Nile Virus are very rare.  The Center for Disease Control and Prevention reports that less than 1 percent of those infected with West Nile Virus will develop severe illness.

Life Cycle of a Mosquito

Mosquitoes undergo complete metamorphosis.

  • Eggs: After drinking blood, adult females lay a raft of 40 to 400 tiny white eggs in standing water or very slow-moving water.  Some species will lay mosquito eggs on moist, often-flooded soil in anticipation of the next rise in water. Those eggs can survive winter, waiting for spring or summer rains to cover them over.
  • Larvae: Within a week, the eggs hatch into larvae  that breathe air through tubes which they poke above the surface of the water. Larvae eat bits of floating organic matter and each other. Larvae molt four times as they grow; after the fourth molt, they are called pupae.
  • Pupae: Pupae also live near the surface of the water, breathing through two horn-like tubes (called siphons) on their back. Pupae do not eat.
  • Adult: An adult emerges from a pupa when the skin molts after a few days. The adult lives for only a few weeks.

Insect Mouthparts

Insects basically have two kinds of mouthparts:  those for biting and chewing and those for sucking.  However, there are many different variations. These mouthpart types can be compared with the functions of common objects:

  • chewing mouthparts (grasshoppers) – scissors
  • sucking mouthparts (stinkbugs, bees, butterflies) – turkey baster
  • stabbing mouthparts (true bugs, mosquito) -juice box drink straws
  • sponging mouthparts (flies) – sponge

Insect Mouthparts Relay Race

Materials:  8 players, 2 scissors, 2 juice box straws, 2 turkey basters, 2 sponges, 2 trays, nuts, water, 4 cups, aluminum foil, 2 plates, 2 bowls

  1. Divide the group into two teams
  2. Each person in the team will pick one of the devices that represent insect mouthparts.
  3. On each tray, place nuts (chewing), water in a cup (sucking), water in a cup covered by aluminum foil (stabbing) and water in a plate (sponging).  Place a large stomach bowl on each tray.
  4. Put the trays at one end of the playing area and line the teams up and the other end. 
  5. The teams race to the tray with their mouthpart, transfer the correct food into the stomach container, then race back to the back of the line.
  6. First team to transfer all their foods wins.

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