Mosquitos are 1/4 to 2/5 of an inch (4-10 mm) long. They are long-legged
insects that have a long, sharp mouthpiece used to puncture skin and suck
blood. Mosquitos have delicate wings and can easily be heard when hovering
around a host preparing for a blood meal. They are more active at dusk or
at night in swampy and woody areas.
Mosquitos require stagnant water to breed (black flies need fresh,
running water). Stagnant water sources can be found in buckets, tires, pools,
marshes or containers left around a property. Mosquitoes have four
stages of development. This is called complete metamorphosis. These
stages are, egg larva, pupa and adult. Eggs must be near water to hatch.
Both the larval and pupa stages are aquatic. The Adult stage is when
the mosquito is free-flying.
Egg: Female mosquitoes choose locations to lay their
eggs where there will be suitable conditions for the larval stage of development.
The characteristics of the eggs follow one of three patterns. The first
is an egg laid singly on the water surface. These eggs will hatch two
or three days later. The second pattern of egg lying is when eggs are
glued together and float on the surface of the water, these are called egg
rafts. These eggs also break apart and hatch two or three days later.
The third pattern is an egg laid singly out of the water. These eggs
are adapted to withstand dry conditions until there are floods and they can
hatch. The pattern of egg lying depends on the specific type of Mosquito.
Larvae: Mosquito Larvae have three distinct body regions,
head thorax and abdomen. The structures of the hairs on both the abdomen
and the thorax can be used to determine what species of mosquito the larva
is. Water is required for larval development. The water must
be either stationary or very slow moving, there must be a food source (bacterial,
fungal, or algal), and there also must be some sort of protection from wind
and waves. Mosquitoes go through 4 stages during the larval stage called
instars. The larvae shed their skin after each stage of development.
At the end of the fourth stage the shed their skin and become pupae.
Pupa: This stage is a short two or three days.
During this stage the mosquito pupae do not eat. Pupae breathe air
through tubules surrounding the openings to the respiratory system.
The pupae stage is also an aquatic stage. When this stage is complete,
the pupae skin splits and an adult mosquito emerges.
Adult: Adult mosquitoes have three body regions, head,
thorax and abdomen. They also have one pair of wings, and three pairs
of legs. Scales on the body regions can be used to identify species.
Both male and female mosquitoes drink nectar and other plant juices.
Only females take a blood meal. The protein from the blood is used
to produce eggs. The life span of mosquitoes varies. Males usually
live a few days to a week, while females may live a few weeks to a few months,
depending on species and location. Mosquitoes are generally inactive
during the day, hiding in grass or shaded areas. Feeding and mating takes
place from dusk until just after dawn.
The first three stages occur in water with the amount of time for
each stage depending on water temperature and food availability. After
emergence, the adults mate and the female seeks out a blood source before
laying its eggs. Up to 100 eggs are laid, either in water, on grass
or other vegetation or in soil close to the water source. When water
is present, eggs hatch into the larval stage (two to three days), although
some species produce eggs which overwinter. Larvae are worm-like organisms
which constantly wriggle around in the water. Adults also get nourishment
from flower nectar.
Most mosquitoes stay close to where they were hatched so they can
raise another brood. Some mosquito species only have one generation each
year. Others can have four or more!
In the winter, most mosquitoes survive as eggs in the soil. These eggs are
in a dormant stage called "diapause" which prevents them from hatching if
it floods. They'll only hatch out of the diapause stage when the day length
gets longer. Some adult females and also some large pupae can survive the
winter (also in a diapause stage) if they can find a protected spot.
Mosquito Borne Diseases in Michigan:
Mosquitoes are the number one killer of humans of all animals. Some of the
Mosquito-Borne diseases include, St. Louis Encephalitis (SLE), Eastern Equine
Encephalitis (EEE), Western Equine Encephalitis (WEE), California Encephalitis
(CE), West Nile Virus, and Dog Heartworm.
SLE: This disease is spread by what is called a “natural” transmission cycle.
The virus is present in infected birds, and the mosquito will take her blood
meal she will ingest the virus. Then the virus will reproduce and move
to the salivary glands. Once the mosquito is infected with the virus,
she can pass it every time she takes a blood meal. Humans are “dead
end hosts” for this virus, meaning they can contract it from and infected
mosquito but the mosquito will not contract it from a human. SLE reactions
in humans may include sub clinical symptoms up to severe central nervous
system symptoms. These may produce temporary or permanent physical
conditions. Generally, people over the age of 50 have a higher fatality
rate and higher risk for permanent damage. In the eastern U.S. SLE
occurs primarily in densely populated urban and suburban areas where birds
and mosquitoes live close to humans. The mosquito that transmits this
disease is the Culex pipien, or the northern house mosquito. This mosquito
is one of the most common mosquitoes found in urban/suburban areas.
They mostly breed in containers that can hold water, which includes trash
cans, flower pots, buckets, gutters, bird baths, etc. They also live
in catch basins, septic tanks, cesspools, sewage lagoons or anything like
these. Culex pipiens over winter as adults, in protected areas such
as garages, but they are mostly active during the warm months of the year.
EEE: Eastern Equine Encephalitis is a virus that causes severe nervous system
damage in humans as well as horses. The fatality rates in humans are
50-70 percent and 90-95 percent in horses. Those who survive may suffer
mental retardation, convulsions and paralysis. Human cases are rare
but horse cases appear every summer. The primary mosquito vector is
the Culiseta melanura, this mosquito is a fresh water swamp mosquito. These
mosquitoes feed primarily on birds; some examples of these birds are blue-jays,
cardinals, and catbirds. There is evidence that humans and horses contract
the virus from many other mosquito vectors, but the significance of these
vectors is not known.
WEE: This occurs in the Western United States and Canada. It occurs
in mostly rural areas, similar to EEE. It occurs in both humans and
horses, but is most severe in children. Symptoms may include headaches,
vomiting, stiff neck, confusion, coma and severe central nervous system damage.
Adults completely recover from this, but children may suffer from permanent
damage. Many mosquitoes are known to transmit this virus but the main
vector is the Culex taralis. They usually breed in ground water with high
West Nile Virus: West Nile Virus in the United States started in the Eastern
states and is making its way across the country. It was found in Michigan
in 2001. The virus causes flu-like symptoms in humans and may cause
death. There were 614 cases reported and 51 deaths in Michigan in the
year 2002. The disease is similar to St. Louis encephalitis.
The disease is most severe in children and elderly people, or people with
weak immune systems. The mosquito vector is the Culex pipien, which
was mentioned earlier.
Dog Heart Worm: Adult heartworms attach to the right heart chamber of the
infected animal. Once the adult female is fertilized she begins to
release microscopic offspring, they are ingested into the blood and develop
in the mosquito. The worm migrates to the mouthparts and then is transmitted
when the mosquito takes her blood meal. The worm is still microscopic
in size but is able to migrate to the heart. The severity of the disease
depends on the age and health of the dog. If dogs are not given the
proper medication the worm can live up to five years inside the dog’s heart.
Also if the dog is not treated mosquitoes that are infected with the disease
may continue to transmit more heart worms to the specific dog. Several
hundred worms can accumulate in the dog’s heart. Heartworms affect
the blood flow of the dog and my cause physiological changes in the animal.
Other animals can get heartworms such as foxes and wolves. Cats may
also be affected by the worms, but are affected in different ways.
WHAT CAN YOU DO TO PREVENT MOSQUITOS IN YOUR BACKYARD???
Many counties of the State of Michigan do not have mosquito management programs,
so the individual must take to initiative to protect his or her home.
There are many ways in which a homeowner can protect himself or herself from
mosquito bites. These are grouped into three primary management areas.
Personal protection is a way to prevent yourself from getting bitten by adult
mosquitoes and prevent mosquito-borne diseases from affecting you.
Larval control is a way of source reduction, or eliminating breeding sites
for mosquitoes. Adult mosquito control is another protective measure
to reduce adult mosquito populations in your yard as well as a way to prevent
mosquito bites from occurring. Below are some suggestions about protecting
yourself and our yard from mosquitoes.
1. Screening: Make sure screen doors are tight fitting
and in good repair. Also make sure camping tents and trailers are also
properly screened. When cabins are not properly screened use a bed
net or mosquito bar when sleeping.
2. Avoiding Mosquitoes: Try to avoid areas where mosquitoes
may be such as twilight hours or wooded areas. When in these areas
be sure to wear protective clothing.
3. Protective Clothing: Protective clothing is tightly
woven materials that cover arms and legs. Studies show that mosquitoes are
attracted to dark clothing.
4. Repellents: DEET is the most commonly used mosquito
repellent. A small amount of repellent can last from two to four hours,
the higher percentage of active ingredients the longer the repellent will
last. Repellents can be applied to skin and to clothing. On clothing
the repellent will last longer. Be sure to avoid eyes, lips and other
sensitive areas when applying repellents.
Larval Mosquito Control:
1. Eliminate any item which can retain water such as tin
cans, tires, jars, bottles, old appliances, broken toys, etc.
2. Repair leaky pipes or outdoor faucets.
3. Empty and clean children’s wading pools at least once
a week, also store in an area where they will not collect rain water.
4. Empty and refill pet water containers daily.
5. Cover garbage cans to prevent water accumulation.
6. Keep eaves troughs clean so water can flow freely and
7. Fill tree holes or stumps with sand or concrete.
8. Keep ornamental ponds stocked with mosquito eating fish
and keep vegetation trimmed.
9. Store boats upside down so they do not collect water.
10. When watering plants or lawn, be sure not to let puddles
11. Drain and fill low areas in your yard to prevent water
Adult Mosquito Control:
1. Keep grass cut short.
2. Cut and remove weeds and brush from yards and adjacent
3. Trim trees and shrubs so that light shows through.
4. Screen outbuildings.
5. Store firewood or lumber ten to twelve feet above the
ground and away from and structure.
6. Screen accesses underneath or into attics of all structures
including basements and cellars.
7. Make wells septic tanks, cesspools; water tanks, etc
are tightly covered and insect proof.
8. Use citronella candles on porches or when camping.
Many people use electronic bug killers to reduce adult mosquitoes, remember
that moths flies and other insects are attracted to ultraviolet light while
studies show that mosquitoes are attracted to the human body!
Did you know that:
There are over 3,000 mosquito species worldwide
Mosquito eggs can survive for more than five years.
One female mosquito can lay over 200 eggs at one time.
Only female mosquitoes bite and take blood. Male mosquitoes feed only on
Not all mosquito species bite people. Some prefer birds, or horses, or even
frogs and turtles.
All mosquitoes need water to complete their life cycle.
A mosquito weighs about 2 to 2.5 milligrams.
Mosquitoes can fly about 1 to 1.5 miles per hour.
Mosquitoes find hosts by sight, by infrared radiation and by chemicals.
Mosquitoes infect 500 million people around the world each year with diseases,
such as encephalitis and malaria.
Mosquito-induced diseases kill more than 2 million people around the world
Mosquitoes are the primary food for many birds and bats. One bat can eat
200 mosquitoes in one night and birds eat hundreds of mosquitoes every day.
Without these mosquito predators, we would really have a mosquito problem!
Parts pf the web page were compiled by Kari Kenel, a GEO 333 student.
This material has been compiled for educational use
only, and may not be reproduced without permission. One copy may be
printed for personal use. Please contact Randall Schaetzl (firstname.lastname@example.org)
for more information or permissions.