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WINTER SALT MARSH
MOSQUITO
GENERAL INFORMATION
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The
Winter Salt Marsh Mosquito (Aedes
squamiger) is one of 53 types of mosquitoes that occur in
California and is a distinctive black and white mosquito that breeds in
California coastal pickle weed tidal and diked marshes. Salt marsh
pools that are diluted by winter and early spring rains are especially
favored breeding sites. Other sites include the cracked ground of
diked wetlands and old dredge disposal sites. This species is a major
pest of humans.
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Adult Daily Activity:
Adults usually emerge during the last weeks of February
through the end of March depending on the amount and timing of the preceding
winter rains. Adults usually fly to areas away from their breeding
sites, using ravines and natural or man-made waterways from the marshes to
the local hills as passage ways. From these passage ways the adults
spread laterally into the wind protected areas of the surrounding community.
Adults then mate, with the females seeking a blood meal and returning to the
marshes to lay their eggs. Mature mosquitoes can live as long as three
months depending on temperature, humidity and other climactic factors.
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Adult Flight Range:
This mosquito readily flies 10-20 miles from its breeding
site.
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Adult Feeding:
Humans and possibly other large mammals are the preferred
hosts for this mosquito. Biting activity occurs most often during the
daylight hours and at dusk from April through June.
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Eggs and Larvae:
Eggs are laid
on plants and along the muddy margins of ponds close to the water line
awaiting submersion by the following years tides and/or rainfall.
It should be noted that the eggs can remain viable for
many years with only part of any one batch of laid eggs hatching during any
single flooding event.
The
larval stage can last as little as a few weeks to as long as a few
months depending on weather conditions and when the eggs hatched.
Optimal larval development occurs in water with salinities of 5-15
ppt (less than 1/2 that of seawater) although complete development
can also occur in seawater. Last stage (fourth instar) larvae
of this species undergo a late winter diapause resulting in a
partial synchronous emergence of the adults.
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DISEASES TRANSMITTED
Winter Salt Marsh Mosquitoes are a serious pest problem when they are
present in large numbers. California Encephalitis virus has been found
in populations of this mosquito although transmission of this virus to
humans has not yet been confirmed.
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WINTER SALT MARSH
MOSQUITO LIFE
CYCLE |
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Winter Salt Marsh Mosquitoes have four life stages: egg, larva,
pupa, and adult. The immature stages need standing water to complete
their life cycle.
After an adult female lays her eggs they hatch into
larvae (wrigglers), which feed on small organic particles and microorganisms
in the water. Feeding occurs when they hang from the water's surface by
the tip of their tail (siphon) or by browsing along the bottom of their
habitat. Because they are air breathing organisms they must return to the water's surface to
breathe. Larval development varies from one to four months depending
on weather conditions with developmental completion occurring near the end
of February. At the end of the larval stage, the mosquito molts and
becomes the aquatic pupa (tumbler). The pupa is active only if
disturbed, for this is the resting stage where the larval form is
transformed into the adult. This takes about two days during which
time feeding does not occur. When the transformation is completed, the
new adult splits the pupal skin and emerges.
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CONTROL METHODS |
| Where possible, the best approach is to prevent mosquitoes from
breeding by modifying their breeding sites. Careful planning
and coordinated efforts with landowners, regulatory agencies and
concerned citizens is essential for any wetlands restoration or
enhancement project. |
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RESIDENTS SHOULD |
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If you have a mosquito problem call your
local Mosquito Abatement District to identify the problem. That
is the first step in identifying what type of mosquito is being
dealt with. |
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Use insect repellents if it is necessary
when in an area where this mosquito is found. Read and follow
the directions carefully! |
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PERSONAL PROTECTION FROM MOSQUITOES |
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FIRST AID FOR MOSQUITO BITES |
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Reduce
outdoor activities during peak feeding periods. |
q
Wash
bite with soap and water. |
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q
Wear
long pants and long sleeved shirts. |
q
Apply
anti-itch medication. |
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q
Apply
insect repellent. |
q
Apply
cold cloth for swelling. |
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q
Watch
for secondary infections. |
For more information on
Winter Salt Marsh
Mosquitoes contact:
Napa County Mosquito Abatement District
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