2017 District Weekly West Nile Virus Monitoring Report


All the Buzz

Mosquitoes are known for their irritating bites, but they’re also important members of the food chain. Mosquito larvae (aka juveniles) help keep marshes and ponds clean by eating bacteria, algae and microscopic plants and animals. (Just one can filter half an ounce of water a day, so a summer’s worth provides a significant environmental service.) In turn, both larvae and adults are food for dragonflies, frogs, fish, turtles and other animals.

Adult mosquitoes live in the shade of shrubs, grasses and other plants but breed in areas near water, where females lay their eggs. Some lay their eggs on the surface of ponds and marshes or on floating vegetation; others look for areas only periodically wet, such as depressions in the ground, bird baths or buckets.

When the weather is warm, mosquito eggs can hatch into larvae within a few days. The larvae remain in the water, but because they need air they’re usually near the surface. They swim around by making jerky movements with their bodies, which gives them the name “wigglers.” In about a week they develop further into pupae, which stay in the water for a few days before emerging as adults.

Both male and female adult mosquitoes get their energy from eating nectar and other plant juices. They use a long tubular mouthpart called a “proboscis” to suck up the liquid. With most species, the females also take in blood but not for food. Some cannot produce eggs without the proteins found in blood; others can produce eggs on their own but lay more after a blood meal.

As a result, even though male and female proboscises have the same basic six parts, those on a female are sized and shaped differently. Two of the parts cut through the skin, two likely help keep it open, one pierces the blood vessel and sucks out the blood, and one deposits saliva. The saliva contains a chemical that keeps the blood from clotting (and causes bites to itch), but it may also help the insects locate vessels in the first place. The saliva is also the substance that carries diseases from infected mosquitoes into the animals they bite.