Pest Management
Mosquito Basics
Did
you know that when you are bitten by a mosquito, that it is a female
mosquito doing the biting? Male
mosquitoes limit their feeding to plant juices and nectar from flowers and
fruit. Female
mosquitoes feed
on these sources for energy also, but need a protein-rich blood meal
to stimulate egg laying.
Mosquitoes
are a very prevalent group of blood sucking insects afflicting man
and other mammals. They
are found throughout the world in almost every natural collection of
water – from mines almost 4,000 feet below ground to 14,000 feet
above the earth’s surface. In
the United States and Canada alone, there are 174 different mosquito
species. There are 76
different species here in Florida. In Charlotte county, we have approximately 37 species.
All mosquito species require aquatic habitats for development during the larval and pupal stages. It is during the larval stage the mosquito is vulnerable to the soil bacteria Bacillus thuringensis var. israelensis (Bti). See also Larviciding Efforts.
Habitats
which support mosquito breeding here in Florida include swamps,
marshes, rain puddles, tree holes, plant axils, ditches, and even
man-made containers such as abandoned tires (see also Mosquito Control At Home). Increasing
land development has led to more storm water runoff, detention
basins, and storm sewers. These
are creating additional aquatic environments capable of supporting
mosquito life.
The
mosquito’s life span varies widely. In some species, about one-third of the adult population dies
daily. While the male
typically lives for only about 2 weeks, the female may survive for 6
weeks to 5 months, depending on the species and the time of year.
Females
compensate for high mortality rates by laying large numbers of eggs
– between 100 and 250 eggs at a time. She is able to lay 4 to 5 broods of eggs in her short
lifetime. Depending on the species, the female lays her eggs either
individually or in clusters referred to as “rafts.” She deposits the eggs on the surface of still water, on the
sides of water-holding containers right above the water level, or on
moist soil prone to flooding. Moisture
catalyzes hatching and development. Mosquito eggs can lie dormant for up to several months, even
a year or more at a time until water washes over them.
After
the eggs hatch, the mosquito enters into a strictly aquatic phase,
the larval stage. Commonly
called a “wiggler” or “wriggler” because of its
characteristic S-shaped swimming motion, the larva feeds on aquatic
microorganisms. Many
species suspend themselves immediately below the water surface
during this stage in order to breathe. To do this, they extend a snorkel-like tube called a siphon,
located at the end of their bodies, piercing the surface of the
water to obtain air.
The
larva grows and sheds its skin – or molts – four times over a 4
to 21 day period before entering the pupal stage, also an aquatic
phase. An even more
active swimmer, the pupa is commonly called a “tumbler”,
describing the tumbling motion it uses to dive into deeper water. During this stage of development, the mosquito does not eat. Like the larva, the pupa also uses a snorkel-like device for
breathing called a trumpet.
After
2 to 8 days, the pupa finishes its development and a winged adult
emerges on the water’s surface, where it must dry it wings. This new adult is capable of flying up to 20 miles or more
from its breeding site. After
mating, most female mosquitoes require a small amount of blood to
nourish their eggs, commonly called a bite. After her blood meal, the female lays her eggs and the
mosquito life cycle begins again.
The
Department takes advantage of the knowledge of this life cycle to
help in the efforts to control these pests. The most environmentally sound and most effective method of
mosquito control is an integrated program that reduces breeding
sites and applies biological controls, such as Bti during the larval
stage. This is known as larviciding. During this stage, these insects are concentrated in well
defined aquatic areas. In
contrast, adult mosquitoes after they disperse from the breeding
sites are difficult and costly to control.
Eliminating
the potential breeding sites, or source reduction, is one of the
most effective means of controlling mosquitoes. A number of source reduction measures homeowners can take
advantage of are listed in Mosquito Control At Home.
When
all other attempts at controlling mosquito larvae fall short and the
numbers of mosquitoes becomes overwhelming, adulticide treatment by aerial or
ground spraying is necessary. State
guidelines must be met before the Department can schedule any
adulticide treatments.
While
some mosquito species pose no threat, others have altered world
history through the transmission of dreaded diseases to humans and animals. Among
these are malaria, dengue, dengue hemorrhagic fever, yellow fever,
filariasis, and encephalitis. Of
these diseases, the various strains of encephalitis virus are the
most serious in the United States.
In
Florida and Charlotte county, our main concern is with St. Louis Encephalitis (SLE). SLE
is caused by a virus that is transmitted by the Culex nigripalpus mosquito, a fresh water mosquito. Other types of encephalitis found in the U. S. include
Eastern Equine, California, La Crosse, Western Equine, and West Nile
Virus.
Sign up to Charlotte Alert to subscribe to our Mosquito Treatment Alert Mailing List
For more information
Charlotte County East Port Environmental Campus
25550 Harbor View Road, Unit 2, Port Charlotte, FL 33980
941.764.4360
