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Are Mosquitos Pests?


Mosquitoes are a bother and huge menace when they swarm in large numbers and when they bite causing itchiness and discomfort to the extent of sometimes causing lack of proper sleep. However, they are more than a nuisance; they are a threat to human population health. They can carry serious diseases that infect humans and animals, including Malaria, West Nile virus, chikungunya virus, dengue virus and eastern equine encephalitis. A lot of effort has been put and continues to be emphasized so as to avoid mosquito bites and the detrimental effects that come with it.

There are over 3500 species of mosquitoes worldwide and they are present in all the continents except Antarctica. However only a few carry pathogens and cause disease. Some of these includes; Aedes, Anopheles and Culex. Mosquitoes are active at dusk and dawn and are most active at 26°C and do not function below 10°C.



There are several Mosquito interventions including clearing of mosquito breeding grounds, use of insecticides, sleeping under treated nets, vaccines etc. However, the best form of mosquito control in the world is known as Indoor Residual Spraying, which is the application of a long-lasting, residual insecticide to potential malaria vector resting surfaces such as internal walls, eaves and ceilings of all houses or structures where such vectors are most likely to come into contact with the insecticide. IRS may also be referred to as Endophilism as it facilitates the blocking of malaria transmission through application of residual insecticides to walls.

Why Do IRS As A Mosquito Control Intervention?

IRS is a WHO recommended exercise as a core vector control intervention. When carried out correctly, IRS is a powerful activity that rapidly reduces adult mosquito vector density and longevity and, therefore, reduces malaria transmission greatly.

45 - Degree Angle


Malaria is spread by mosquitoes. Every year millions of people around the world get malaria and over half a million people die from malaria every year, mostly children and pregnant women. Malaria causes fever and chills but it’s best diagnosed with a blood test. Several medicines treat malaria, but the parasites are becoming resistant to the medicines and that is why there is an emphasis on prevention more than cure and that is why conducting IRS is crucial especially in areas prone to it.

Malaria used to occur almost everywhere in the world. Now it's mainly in warmer parts of the world such as:

  • South America
  • Central America and islands in the Caribbean
  • Africa
  • India and other parts of South Asia
  • Middle East


1.Where people sleepWhere no one sleeps
2.Walls made of mud, stone, bricks, grass, plastered and woodCattle sheds
3.More than 30 meters from the highest watermarkWalls made of iron sheets, metal or grass
4. Walls with perforations or half walls
5. Too close or <30 meters from a sensitive eco-system a good example being a water body


IRS is effective since most malaria vectors are endophilic i.e. tend to rest indoors. Once they do that, they take in the lethal dose thus reducing their lifespan. Progressive decline in vector density and longevity, especially among older female mosquitoes, and a reduction in overall vectorial capacity hence reduction in malaria transmission. IRS is most effective against indoor feeding (endophagic) and indoor-resting (endophilic) vectors. Greatest impact of an IRS intervention takes place after feeding, when the anopheline mosquito also known as marsh or nail mosquito is more likely to rest on a sprayed surface and pick up a lethal dose of selected insecticide, thus preventing it from transmitting malaria parasite to others in the vicinity. For the best results when it comes to IRS, there must be high coverage, usually over 85% coverage of all structures that are potential resting places. This will ensure one obtains the “mass effect”.


  • Proper training of spray operators
  • Selection and proper use of the most effective equipment
  • Precise planning, preparation, and logistics
  • Correct insecticide selection
  • Dedicated and disciplined spray operators
  • Well-organized and diligent supervisors
  • Good data recording and prior communication
  • Enough staff, procurement, environmental compliance, and other tasks

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