Note: The following is a Zodiac Revisited archive of the article “New traps monitor mosquitoes” from the Durango Herald. It documents mosquito traps used in Colorado during the height of the West Nile virus. The traps share some similarity with the Zodiac’s bus-bomb diagrams. The article was on durangoherald.com earlier, but it’s no longer available, neither at the Durango Herald website nor any of the internet archives.
New traps monitor mosquitoes
September 12, 2004
By Dale Rodebaugh
Herald Staff Writer
The tax increase approved by voters last year has provided money to allow the Animas Mosquito Control District for the first time to trap potential carriers of the West Nile virus, according to district manager Sterling Schaaf.
“Trapping mosquitoes means instantaneous answers to questions,” Schaaf said Thursday during a visit to one of 10 traps set throughout the district. “You know if you have mosquitoes, how many you have and if they are positive for the West Nile virus.”
Traps are spread throughout the district, which stretches from Baker’s Bridge in the Animas Valley to the northern edge of the Southern Ute Indian Reservation at County Road 213, and from Falls Creek to Edgemont Ranch, Schaaf said. The most likely sites of mosquito breeding are targeted – marshy areas, sewer lagoons, hay fields and stock ponds.
Since the program began May 15, two West Nile-positive mosquitoes have been found, Schaaf said. One was found in the southern end of the district on Aug. 19, the other, on Aug. 24 on the east side of the Animas River south of Trimble Lane. Trapping probably will continue to Nov. 1, he said.
Six mosquito species found in this area can carry the West Nile virus, but only one – Culex tarsalis – has been shown to actually be a carrier, Schaaf said. Male mosquitoes can carry the West Nile virus, but only females in search of blood for egg development bite people or animals.
Traps rely on basic technology – a 6-volt car battery, a flashlight bulb, a small fan, a collection net and a 1-gallon thermos. A spigot on the thermos full of dry ice allows a stream of carbon dioxide – a mosquito attractant – to escape. The car battery powers the light bulb (light also attracts mosquitoes) and the fan. Approaching mosquitoes are sucked into the trap and held there by the stream of air from the fan.
Traps are checked five days a week. They are set out Monday afternoon and picked up Saturday morning. Schaaf said traps have contained no mosquitoes to 1,182 of the pests.
The tax increase, approved last year by about 60 percent of those who voted, costs the owner of a $200,000 house about $9 more this year than last. The additional money covers the cost of inflation and the hiring of four new employees, two of whom test mosquitoes for West Nile virus. The district also bought a small launch to reach points along the Animas River where spraying can occur. Dry ice costs $250 a week, Schaaf noted.
The size of the Animas Mosquito Control District has doubled in 14 years, Schaaf said. Employees cover 19 routes looking for sources of mosquito larva, including stock ponds, bird baths and old tires. One route has 285 stops, Schaaf said.