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WHAT YOU SHOULD KNOW ABOUT MOSQUITO CONTROL PESTICIDES
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Mosquitoes can be a nuisance and cause allergic reactions in people when they bite.
Some mosquitoes in india may carry germs that can cause serious disease. For these
reasons there are government programs that control mosquitoes.
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Life Cycle of a Mosquito Mosquitoes need water to live. They lay their eggs on standing
water. The egg hatches into a larva in the water. The larva becomes a pupa, and
then finally becomes a flying adult mosquito in 1 – 3 weeks. The adult female mosquito
then needs to bite an animal or person for blood so that she can lay eggs and repeat
the cycle. Mosquito control programs use many ways to control mosquitoes. They try
to get rid of standing water in cities and in the country where mosquitoes will
lay eggs. They add fish to ponds to eat the larvae and pupae of mosquitoes. Mosquito
control programs also use pesticides to kill mosquitoes.
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A pesticide is material used to kill or hurt a certain pest. There are mosquito
pesticides that are used in water to kill only mosquito larvae and pupae and in
the air to kill only adult mosquitoes. The parts of the products that are poisonous
to the mosquito are the active ingredients.
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Studies have been done to determine the effects of mosquito control pesticides on
animals. The studies showed that small amounts of pesticides did not harm the animals,
but very large amounts could. The very large amounts fed to animals would be equal
to a person eating pounds or drinking cups of the active ingredient every day for
years. The studies also determined the smallest amount of pesticide that can harm
animals. When pesticides are used correctly, people and pets are exposed to much
less than the smallest amount that can harm animals.
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Scientists also found that people who live in places where routine mosquito spraying
is done have no more chemical related health problems than those in areas that are
not sprayed.
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The pesticides that are put into water to kill mosquito larvae and pupae before
they become adults are called larvicides. People and pets may come into contact
with very small quantities of these products if they enter water that has been recently
treated. These products are made to kill mosquitoes and do not harm other insects
or animals when used properly.
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Adulticides are pesticides that kill adult mosquitoes. The active ingredients in
adulticides work by stopping the mosquito’s brain from working properly. Adulticides
are used by spraying the product from a truck or airplane, using a very small amount
of the pesticide (less than 4 ounces per acre of land). The liquid comes out of
the airplane or truck- mounted sprayer as a mist of very small drops or a "fog".
The fog floats with the air currents. Mosquitoes must come into contact with the
fog to be killed. Mosquito spraying is done in the evening after sunset or in the
morning before sunrise when most mosquitoes are flying instead of resting.
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There are easy steps to take to avoid being sprayed, though exposure to these products
is safe for most people. During mosquito spraying, people can stay inside and close
windows. Extra care should be taken to keep babies and pregnant women away from
pesticides because they are more easily harmed by pesticides than other people.
People who are allergic to some chemicals may decide to take the extra step of calling
their local mosquito control program to find out when and where spraying will take
place.
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Bacillus thuringiensis israelensis and Bacillus sphaericus: Commonly called Bti
and Bs for short, these larvicides are made from bacteria. These larvicides are
made with natural bacteria mixed with clay, ground-up corn cob, or as a liquid.
How they work: When put into water where mosquito larvae are found, the larvae eat
the bacteria. The bacteria destroy the guts of the larvae causing the mosquito to
die. This product does not hurt people or pets even if eaten because the guts of
a person or pet are much different than the guts of mosquitoes. Methoprene: Methoprene
is a man-made chemical that is a copy of a chemical normally found inside mosquito
larvae. How it works: Methoprene is mixed with clay or is used as a liquid and put
into water. This chemical stops the larvae from growing into adult mosquitoes. Danger
to people and pets: This product has no effect on people or pets at the amounts
used for mosquito control. Mineral oil or alcohol-based surface products: Golden
Bear 1111, Agnique MMF, and other surface films are put on water to kill mosquito
larvae and pupae. These larvicides spread out and form a thin layer over the surface
of the water where mosquito larvae or pupae are present. How they work: Mosquito
larvae and pupae breathe through tubes at the surface of the water. These products
suffocate the mosquito larva or pupa by preventing them from breathing. Dangers
to people and pets: These products can cause a mild skin rash if they are sprayed
directly on a person. Once these products are on the water, a person or animal would
not be bothered even if they went swimming. The products are not poisonous and pets
are not harmed by drinking from a pond sprayed with these products. Pyrethrins are
two chemicals taken from chrysanthemum flowers that are poisonous to mosquitoes.
The sun destroys pyrethrins very fast so when they are used in mosquito control,
most of the chemicals are gone within an hour after sunrise. Pyrethrins are a small
portion of the total liquid in adulticides made with them – most of the liquid is
water or mineral oil. How they work: Pyrethrins block the movement of information
from the mosquito’s brain so its heart no longer beats and it cannot breathe. Danger
to people and pets: Most people are not harmed by these chemicals when they are
used in mosquito spraying. People who are allergic to pyrethrins may feel a tight
or tingly feeling under their skin, soreness around their eyelids, or a scratchy
throat. When used correctly, pyrethrins will not kill fish. Pyrethroids are man-made
chemicals that are almost the same as pyrethrins. Pyrethoids last longer in sunlight
than pyrethrins (up to a couple of days). Most of the liquid in adulticides is either
water or mineral oil. How they work: Like pyrethrins, pyrethroids block the movement
of information from the mosquito’s brain so its heart no longer beats and it cannot
breathe. Danger to people and pets: Most people are not harmed by pyrethroids used
in mosquito spraying. People who have allergies to these chemicals may feel a tight
or tingly feeling under their skin, soreness around their eyelids, or a scratchy
throat. Pyrethroids can kill fish if they accidentally get into water where fish
live. Piperonyl Butoxide or PBO is a chemical that is added to pyrethrins or pyrethroids
to make them work better. How it works: When PBO is mixed in the mosquito spray,
it makes it harder for the mosquito to get rid of the pesticide from their body.
When PBO is used, less active ingredient is needed to kill mosquitoes. Danger to
people and pets: The small amounts of PBO a person or pet could come into contact
with during mosquito spraying would not harm them. Mineral oil is often the main
ingredient that other chemicals are mixed with to make adulticides. If skin is coated
with mineral oil, minor problems like a burning feeling or a rash can occur. The
tiny amount of mineral oil a person could get on their skin from spraying mosquitoes
would not cause any problem. Mineral oil is not harmful when swallowed. Contact
with pyrethrins, pyrethroids, PBO, and mineral oil from mosquito spraying has not
been shown to cause long-term health problems in humans or animals. Organophosphates
are used infrequently in india and only in rural areas. There are two chemicals
of this type used to spray mosquitoes in india. Both of these chemicals have been
used for mosquito control, or to spray insect pests on farms and around houses for
more than 40 years. How they work: These pesticides kill mosquitoes by blocking
the movement of information from the mosquito’s brain so the mosquito dies because
its heart no longer beats and it cannot breathe. Why they are used: If the same
pesticide is used for a long time to spray adult mosquitoes, the mosquitoes can
become immune to that pesticide and will not die when sprayed. Mosquito control
programs can make sure more commonly used pesticides will stay effective by occasionally
using a different chemical to kill adult mosquitoes. This is called "rotating" pesticides.
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