Entomology: Mosquitoes, Flies, Louse, Flea

The study of insects is known as entomology. The kingdom Animalia includes three classes, and we will read about the class Insecta.

Insects have a head, thorax, and abdomen. It has wings and 3 pairs of legs. They mostly inhabit the land. It includes mosquitos, flies, louse, and fleas.

Mosquitoes

This includes two families: Anophelini and Culicini. Family Anophelini has the famous Anopheles mosquito, while Family Culicini includes Aedes, Culex, and Mansonia.

Let us read about the diseases caused by them one by one.

1. Anopheles mosquito
   • It is also known as a Sophisticated Mosquito.
   • It lays eggs singly in clean, stagnant waters.
   • Eggs: Boat-shaped with lateral floats.
   • Inclined, resting on the skin surface with head down. It has an inclination of 45 degrees. 
   • It has spotted wings.
   • Larvae of Anopheles
     • Near the surface,
     • Rests parallel to the water surface.
     • No breathing tube (siphon tube) is present.
   • Anopheles mosquito transmits malaria.
2. Aedes:
   • It is also known as a Man-made mosquito or tiger mosquito.
   • It is found in artificial waters (ACs, coconut shells, buckets)
   • It lays Eggs, Singly, and the eggs are Cigar shaped
   • It has a Hunchback position with white stripes on the entire black body.
   • The larvae of Aedes mosquitoes have a shorter siphon tube. They can Breathe below the water's surface.
   • Aedes transmits Dengue, Chikungunya, Rift Valley fever, and Zika virus.
3. Culex
   • Known as Nuisance mosquito.
   • It lays eggs in dirty & polluted waters.
   • It lays eggs in Clusters or Rafts (100-250 eggs in one cluster).
   • Culex mosquito has a Hunchback position, a small body, longer legs, and NO white stripes on the black body.
   • The larvae of Culex have a long siphon tube or breathing tube, which allows them to Breathe below the water surface. The larvae rest at an angle to the water surface.
   • Culex transmits Japanese encephalitis, Filariasis and West Nile fever
4. Mansonia
   • Lays eggs under aquatic plants like Pistia and Water hyacinth (water lily).
   • It lays star-shaped eggs in clusters.
   • Mansoni has a Squatting position, a big body, and white spots on their legs.
   • Mansonia transmits Brugian filariasis.

As Mosquitoes cause so many dangerous diseases, we need to control their proliferation. There are certain control measures. These are also known as Integrated vector management:

• Anti-larval measure:
  • Environmental ECP
  • Source reduction
  • Chemical control: by the use of Screen and Temephos (Abate)
  • Biological control: by using certain species of Fishes and Anti larval bacilli
• Anti-adult measure
  • DDT
  • Malathion
  • Pyrethroids
• Personal protection measures that an individual can use
  • Mosquito repellants
  • Mosquito screens
  • Mosquito nets

Flies

Sandfly

• Sandfly has Lanceolate-shaped wings. It is hairy and has Long legs.
• It does not fly, it hops (50-70 meters).
• Its main Habitat is Cool, damp places (moist soil, stone walls, rubbish heaps, burrows)
• It has Nocturnal Biting habits, and Only females suck blood.
• Adults live about 2 weeks. It Takes 2-3 blood meals during a lifespan. 
• There are specific species that carry certain diseases. They are:

Sandflies cause a list of diseases, and therefore, we need control measures to prevent them.

The Cracks and crevices are to be plastered. The insecticide of choice under NVBDCP is Malathion, a synthetic pyrethroid with no resistance. Sulfur fumigation, formalin cresol, or DDT spray can also be used to kill adult flies (5% DDT in kerosine oil).

Louse

• They are dorso-ventrally flattened and have no wings. They have three pairs of legs. Their life cycle has stages: adult, Eggs, Larvae, and Adult.
• Life span of adult louse: 1-2 months
• The mode of transmission is through Direct contact or fomites (inanimate objects)
• Malathion is the method of control.

Fleas

• Bi-laterally compressed
• They have no wings
• They have Bristles over the body, particularly on legs directed backward.
• Their main Habitat is  Rat burrows, cracks & crevices of floors
• Mode of transmission: Bites
• Methods of Control:
  • DDT (10%)
  • Malathion (5%)
  • Cyano gas (Neurotoxic)
  • Diethyl toludamides
  • Benzyl benzoate

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