Observer News

Source Reduction Means Mosquito Reduction

With the beginning of the mosquito season comes the need for protecting individuals and communities from mosquitoes. When you use the GLOBE Observer Mosquito Habitat Mapper tool, you are not only providing useful surveillance information about when and where mosquitoes are found: you also are providing an important public service known as “source reduction.”Take a look around your home, park and school to see where you can reduce mosquito breeding in your neighborhood:

  1. Remove all unnecessary containers where water can accidentally accumulate. Make sure water in pet bowls and in saucers under plants is refreshed no less than twice a week.
  2. Clean debris from gutters, where water can pool and become stagnant.
  3. Remove standing water and seepage from around intentional water storage, such as cisterns and rain barrels, and make sure that stored water is covered with a lid or net and/or larvicide.
  4. Grade and drain standing pools of water that are found near septic systems, cesspools, and ditches, and make sure that irrigation equipment is adjusted so it doesn’t create puddles.

The last step in the Mosquito Habitat Mapper is to remove a breeding site from use whenever possible. This is an important step because container sites hiding in and around your home or school are unlikely targets of your local mosquito control agency. Public departments tend to concentrate their efforts on remediating large breeding sites, such as swamps, ponds and standing water in ditches. If you find a productive breeding site that requires more than “tipping and tossing,” you can report it to your local mosquito control department.;

Public mosquito control typically uses Integrated Mosquito Management techniques that include using chemical and non-chemical control methods. Non-chemical methods include deploying bacteria harmful to mosquitoes and predatory fish and invertebrates in ditches and ponds. Bti (short for Bacillus thuringiensis subspecies israelensis) is a naturally occurring bacterium found in soils, whose spores produce toxins that kill mosquito larvae but are harmless to humans and other wildlife. Toxorhynchites is a genus of mosquitoes whose giant larvae are cannibals that prey on other mosquito larvae, and they are sometimes used by mosquito control agencies to reduce or eliminate larvae of harmful mosquitoes. Fun fact: immature Toxorhynchites obtain enough protein through predation of other larvae so that as adults, the females do not need to obtain a blood meal to produce eggs.

You may have seen a fogging truck driving through streets in your community, spraying mosquitoes with adulticides in the evening. Application of adulticides can rapidly decrease the number of mosquitoes. However, adulticides also tend to be toxic to organisms other than mosquitoes, so they are used with caution and in limited quantities.


This Toxorynchites specimen was identified in a bromeliad (a plant that can have a water collecting cup or receptacle in its center where the leaves meet). Plants such as bromeliads and stems of cut bamboo are often used as breeding sites by mosquitoes. This specimen was found by a citizen scientist in Matinhos, Brazil while using the GLOBE Observer Mosquito Habitat Mapper.


Adult mosquitoes find shelter in weeds and vegetation, so cutting down weeds and mowing grass can reduce the number of mosquitoes around your home.

You can test your ability to visually identify and locate mosquito habitats with the Mosquito Zapper! digital game (requires Adobe Flash). Students might want to create their own games that depict the common breeding sites where they live (it would be great to see their game mock-ups).

While the mosquito larvae that you are observing when using the Mosquito Habitat Mapper are harmless, adult mosquitoes may be present. As you take steps to protect your community, be sure to protect yourself whenever you are outside and expect to be exposed to biting mosquitoes. Wear light colored clothing that maximizes coverage of biting surfaces and apply mosquito repellent on exposed skin. See CDC’s mosquito bite prevention document for information on how to select and apply mosquito repellent

For more information on mosquito prevention and protection, download the flyer from the American Mosquito Control Association


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A graphic showing silhouettes of two people taking observations with their phones. They are standing between water with mosquito larvae in it, grass, trees, and clouds, which represent the tools within the GLOBE Observer app.

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