|  Collecting
adult mosquitoes can provide several important pieces of information.
When traps are set at specific locations over a period of time,
or in response to service requests, increases in the mosquito
population can be detected. Once these mosquitoes are identified,
control measures can then be more easily directed. Knowing what
species of mosquito is breeding can help Vector Control Technicians
find the breeding source and take the appropriate control measures.
After identification by District Staff, these mosquitoes can
also be tested for the presence of disease. The detection of
virus in a mosquito which feeds on humans indicates a true potential
for human disease, and immediate control measures can be implemented.
Trap collections not only determine where control measures are
needed, but also determine the effectiveness of control measures
which are in place.
CDC-Type CO2-Baited Trap
This trap is used to selectively sample host-seeking females
attracted to the trap by the sublimation of dry ice into carbon
dioxide (CO2) which simulates the exhaled respiratory gases
of birds or mammals. The trap consists of a central 3"
diameter plastic cylinder housing a 6V DC motor and a 4"
fan blade, a collection net attached to the bottom of the cylinder,
a 6V battery power source, and an insulated container with 2-5
pounds of dry ice. CDC-type traps utilized by the District also
incorporate a mini-light source which help attract mosquitoes
as well. Mosquitoes attracted to the trap are drawn in through
the top of the trap and forced downward by the fan into the
collection net. Live-trapped females can be counted and tested
for mosquito-borne arboviruses.
Gravid Trap
 This
trap selectively samples gravid (ready to deposit eggs) female
house mosquitoes (Cx. pipiens) that are seeking suitable oviposition
sites. The gravid trap incorporates three components: a base
reservoir filled with oviposition attractant (hay or manure
infusion), a vertically-directed suction apparatus and a top
mounted collection carton. The intake orifice of the suction
apparatus is positioned one inch above the surface of the oviposition
attractant. Gravid females attracted by the infusion descend
into the base reservoir where they are swept into the suction
apparatus and directed upward into the collection carton.
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