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Garfield maps skeeter sites

Jeremy Heiman

GLENWOOD SPRINGS – Get ready for … Slap! … mosquito season.

The company hired to fight mosquitoes in Garfield County this year has mapped about 650 sites where the insects are likely to breed – and there are more to come.

The biggest part of the mapping is now done, said Peter Bonkrude, Garfield County operations manager for Colorado Mosquito Control, but the company expects to identify as many as 100 more sites before the season is over. Bonkrude and his staff are waiting for information from a few ranchers and others in rural parts of the county, he said, but the main mapping is done.

After the mapping comes the trapping.

Bonkrude, with some expert help, will be checking his traps and looking for the culex tarsalis mosquito – the primary carrier of West Nile virus.

This could be a big year for West Nile. West Nile virus infected 2,945 Colorado residents last year, killing 55. The disease is known to be most virulent in the second year it affects an area.

West Nile was first seen on Colorado’s Western Slope in the summer of 2003, so 2004 is expected to be a bad year, officials say. The disease first affected the plains and foothills of eastern Colorado in 2002.

Right now, it’s still too early for the mosquitoes, so Bonkrude can only look for potential mosquite breeding sites.

“It looks like Rifle is going to be one of our biggest areas,” he said. His workers have identified about 150 potential breeding sites in and around that city.

The areas around Parachute and Battlement Mesa have plenty of standing water sites where mosquitoes can breed, too.

In New Castle, Bonkrude said, the area with the most breeding sites is Castle Valley.

“They have those weird little ditches that run through the area,” he said. These catch and hold water, providing places for the insects to lay their eggs.

The city of Glenwood Springs is probably going to present the least problem. Bonkrude described the town as “citified,” and said few wild areas remain where ponds or depressions hold water. Two Rivers Park is one place where some work may be necessary to control mosquito larvae, he said.

“Glenwood’s biggest problem is going to be the corridor between Glenwood and Carbondale,” he said. The agricultural areas, golf courses and riverbank areas have numerous water-holding pockets.

Mosquito breeding sites come and go

Bonkrude and his crew are wrapping up the mapping of breeding areas within the 50-square-mile mosquito control district, but that doesn’t mean the maps won’t change. Sites with potential to hold standing water must be visited throughout the season, even though they’re dry on the first visit.

“One time you go to the site, and there’s no water. You go back, and it’s breeding,” Bonkrude said. “I’ve kind of shut off the part of my mind that gets surprised.”

The next phase of the mosquito control campaign will be placing traps that will give the company an idea of what species of mosquitoes are present and in what quantities. They will be looking for the culex tarsalis.

Colorado Mosquito Control’s foremost mosquito expert, Michael “Doc” Weissman, who has a Ph.D. in entomology, joined Bonkrude on Saturday to guide him in the placement of mosquito traps. Where traps catch large numbers of adult mosquitoes, control programs will be intensified.

Residents called on for help

The company also hopes that residents will contact them if their mosquito problem is out of the ordinary.

“That’s a big part of our program,” Bonkrude said. “We really rely on citizens to call us with complaints. If somebody says, ‘Man, I was really being eaten alive out at my place,’ we’ll put a floater trap out there.”

“Floaters” are traps that the company will move around from time to time throughout the summer. There will also be permanent traps that stay in the same place all season, to show the rise and fall of insect populations.

The company will be using traps that attract mosquitoes with carbon dioxide and also have a light that attracts the bugs.

“They kind of look like big lanterns,” Bonkrude said.

Also starting soon will be the company’s larvicide treatments of standing water. The larvicide used will be the bacterial agents Bacillus thuringiensis israeliensis and Bacillus sphaericus, which only attack mosquito larvae.

Bti is sold in donut-shaped cakes that are placed in shallow water. Bacillus sphaericus is distributed as a granular substance that can be spread by hand or sprayed as a wet mixture.

Larvae now active

Larvicide will not be placed in any standing water unless mosquito larvae have been found there. Colorado Mosquito Control employees have been finding a few larvae for the past two weeks, Bonkrude said, but have not yet seen adult mosquitoes.

Colorado Mosquito Control will mainly concentrate its efforts in the most heavily populated areas of Garfield County, in and around the towns in the county. But some of the mapping and trapping is being done in outlying areas that are used heavily for recreation – the Sweetwater area, Rifle Mountain Park, Harvey Gap, and areas along Fourmile Creek will be treated, Bonkrude said.

No mosquito control program can be expected to completely protect residents from mosquito bites, so residents are advised to wear mosquito-repellent products, especially in the early morning and at dusk.


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