Los Angeles County West Vector & Vector-Borne Disease Control District
Control & Surveillance
The District uses an
integrated mosquito management approach to prevent and control mosquitoes that
spread viruses like West Nile virus and Zika. Methods are based on an
understanding of mosquito biology, the mosquito life cycle, and the way
mosquitoes spread viruses to develop plans for controlling mosquitoes.
Physical control reduces mosquito populations
through the modification and management of the environment. Examples of physical
control include eliminating breeding sources and removing debris and vegetation
to promoting effective drainage.
Microbial and chemical control involves the application of EPA-approved
insecticides to larval habitats of mosquitoes in accordance to federal and state
laws and regulations and in compliance with the chemical label.
Biological control is the use of mosquitofish, Gambusia affinis, to
manage mosquito populations in ornamental ponds, unmaintained swimming pools,
and animal water troughs.
of the over 50 known species of mosquitoes in California can carry
disease under the right conditions. When a female mosquito takes a
blood meal, she may transmit certain disease-causing organisms to
humans and other animals.
The District conducts mosquito
surveillance to understand what types and numbers of mosquitoes are
in an area. Surveillance allows the District to identify mosquito
species and determine appropriate control measures.
Mosquito virus activity is
monitored by testing adult mosquitoes for the presence of WNV, SLE,
and WEE. This research and surveillance information helps guide all
control efforts. The detection of virus in a mosquito which feeds on
humans indicates a true potential for human disease.
District uses several types of traps to monitor mosquito
CDC-Type CO2-Baited Trap
Used to trap host-seeking females attracted by the
sublimation of dry ice into carbon dioxide which simulates the exhaled
respiratory gases of birds or mammals. Mosquitoes attracted to the trap are drawn in through the top of the trap and
forced downward by the fan into the collection net.
Traps gravid (ready to deposit
eggs) female Culex mosquitoes that are seeking suitable egg laying sites.
Gravid females are attracted to the egg laying attractant (hay
infusion) and are swept up into the collection container.
CDC AGO Trap
The ovitrap is designed and used to trap
invasive Aedes mosquitoes that prefer to lay their eggs on the interior
walls of containers, such as Aedes albopictus (Asian tiger mosquito) and
Aedes aegypti (yellow fever mosquito).
Gravid female Aedes mosquitoes are attracted to
the hay-infused standing water and seek to lay their eggs on a hard surface
right at the water line.
Sentinel chickens represent a critical
element of the District's surveillance program and help to prevent any
transmission of mosquito-borne diseases to the human population. The
District maintains flocks of chickens located strategically throughout the
District and tests them every two weeks.
The samples are tested at the California Department of Public Health
Vector-Borne Disease Laboratory for antibodies to WNV, SLE, and WEE.
infected birds, especially crows, jays and ravens, are known
to get sick and die from WNV infection. Reporting and testing of
dead birds is one way to check for the presence of WNV
in the environment. Dead bird reports are often the first indication
that the virus is active in an area.
What should I do if I find a dead bird?
If you find a dead bird, particularly a crow, jay,
magpie, raven, sparrow, finch, or raptor, please file an online
http://westnile.ca.gov/report_wnv.php or call toll-free
If local authorities tell you to simply dispose of the birdís
carcass (body), use gloves or
an inverted plastic bag to place the carcass in a garbage bag, which
can then be disposed of in your regular trash.