View Sidebar

Archives

 

Categories

 

Mosquitoes

Biology

Mosquitoes are small, long-legged, two-winged insects belonging to the order Diptera.  Worldwide, there are over 2,600 known species.  In Indiana, fifty-three species have been identified.

Mosquitoes have four distinct stages of development:  egg, larvae, pupae, and adult.  Eggs must be in water in order to hatch.  Larvae and pupae are aquatic; adults are active, free-flying insects.

Male mosquitoes emerge from the pupal stage about twenty-four hours before the females.  Mating occurs within forty-eight hours, so the majority of females in any population are always fertile.  Both females and males utilize nectar and other plant juices as energy sources; only females take a blood meal, utilizing the protein to produce eggs.

Mosquitoes can be placed into two categories.  One category consists of mosquito species that lay their eggs on the surface of water, while the other category is mosquitoes that lay their eggs on a moist surface next to or above water.  Mosquitoes in the second category can be labeled “floodwater” mosquitoes.  They will hatch when the water covers the eggs and the conditions are correct.  An example is eggs are layed on wet leaves next to a low area in the middle of the woods.  A heavy rain fills up the low area and the eggs are covered.  If the temperature is warm enough, the eggs hatch.  If there is no rain, the eggs are protected by a hard cover and may survive up to ten years.  The majority of nuisance mosquitoes are floodwater species, such as Aedes vexans and Psorophora ciliata.  Aedes triseriatus, a vector of LaCrosse Encephalitis, lays her eggs along the insides of treeholes and artificial containers.

Surface egg-laying mosquitoes deposit their eggs singly or in rafts that may hold 100 to 200 eggs.  Culex species lay egg rafts on water in clogged gutters, tires, birdbaths, dried-up ditches, and un-maintained swimming pools.  Anopheles species lay several single eggs on open bodies of water.

Mosquitoes also differ in the time of day when biting occurs.  Some species bite during the day, while others only bite at night.  Aedes triseriatus is a day-time biter, while Culex pipiens is a dusk to dawn biter.

Diseases

Mosquitoes kill more people than sharks, but people are more afraid of sharks than mosquitoes.  The insects are responsible for the spread of many diseases throughout the world.  Yellow fever, malaria, dengue, and elephantitus are common in tropical regions.  For those of us living in the Midwest, encephalitis is the disease of most concern.

Encephalitis is an inflammation of the brain, which can be caused by a mosquito-borne virus.  The onset of the disease is usually sudden and the symptoms may include high fever, headache, nausea, vomiting, stiff neck, dizziness, drowsiness progressing into a coma, muscular twitching, and convulsions.  Some patients have speech difficulties, are mentally confused, lethargic, and show tremors of the tongue, lips, and hands, while others are irritable, confused or irrational.  In some cases, there may be spastic paralysis.  The eyes may be involved, causing double vision in the individual.  Reflexes, such as the knee jerk, are exaggerated.

In Indiana, there are four kinds of mosquito-borne encephalitis of major concern:  West Nile virus (WNv), LaCrosse Encephalitis (LAC), St. Louis Encephalitis (SLE), and Eastern Equine Encephalomyelitis (EEE).

Diseases:

Prevention & Control

WHAT CAN THE PUBLIC DO TO PREVENT & CONTROL MOSQUITOES?

All mosquitoes require standing water (at a minimum of 1/4 inches deep) for the first three stages of development.  Consequently, the elimination of any vessel capable of holding water for extended periods of time is essential.

  • Check your property for breeding sites.
  • Clean out leaves and debris from clogged gutters.
  • Do not allow tires to accumulate outside.
  • Flush out birdbaths once a week.  Empty or turn over wading pools when not in use.
  • Dispose of containers, trays, and can that can hold water.
  • Cover or store canoes and boats upside down.
  • Maintain backyard swimming pools and spas to discourage the development of mosquitoes.  If not going to use the pool, then place a cover over the pool and pitch it in the middle so the cover will not collect leaves and rain water.
  • Aerate ornamental ponds and water gardens.
  • Limit time spent outdoors during peak mosquito biting times.
  • Wear loose, light-colored, long sleeves and pants.
  • Use a repellant that contains DEET, picaridin, oil of lemon eucalyptus or IR3535.  Repellants can be used on children, 2 months and older, but check the label before applying.
  • Purchase a hand-fogger to use when working outside or having a backyard party.

Prevention & Control Information

Repellant Information

Biological Control

Biological control requires introducing a natural predator into the habitat of the mosquito.  Dragonflies, praying mantids, bats, and purple martins have been promoted as natural controls, but have not shown the ability to significantly reduce mosquito populations.

Gambusia affinis, also known as “mosquitofish”, are a top-feeding guppie that offer excellant control of larvae and pupae in ornamental ponds and backyard garden pools.  These fish have upturned mouths and work along the surface, feeding on mosquito larvae and other small invertebrates.  They are somewhat tolerant of organic pollution and reproduce rapidly.

Since the fish will interfere with the life cycle of other aquatic organisms around them, certain restrictions apply as to where they can be used.  In general, they cannot be placed in an area, such as rivers, creeks, ditches, and lakes, where they will interfere with any Indiana game fish.

Helpful Information: