Public enlisted in battle against West Nile virus |

Public enlisted in battle against West Nile virus

Jeremy Heiman
Special to the Post Independent

Mosquito control isn’t for experts only.

Several products are available over the counter that ranchers, farmers and residents can use to manage mosquitoes on their own property.

Steve Anthony, vegetation manager for Garfield County, said the products can supplement the work done by Colorado Mosquito Control, the contractor hired by the county to fight mosquitoes that carry West Nile virus.

“We recommend using them,” Anthony said, “if you’ve got ponds, irrigation, or any kind of standing water.”

In its life cycle, a mosquito passes through four stages ” egg, larva, pupa and adult. The most effective products sold over the counter attack mosquitoes in their larval stage.

The main carrier of West Nile virus, a species called culex tarsalis, lays its eggs in rafts of about 300 in still water. Wriggling larvae hatch from the eggs and feed on microscopic organisms, organic matter or algae, which they filter from the water, before transforming into comma-shaped pupae and later emerging from the water as adults.

One product sold at the Roaring Fork Co-op in Carbondale is Mosquito Dunks. These are small doughnut-shaped briquettes containing Bacillus thuringiensis israeliensis, or Bti, bacteria that attack mosquito larvae.

The doughnuts, which float, are placed in standing water where mosquitoes breed ” places like stock ponds, irrigation ponds and wetlands. One doughnut is enough to treat 100 square feet of surface area and lasts 30 days. They can be broken into smaller pieces for treating smaller areas of water.

These doughnuts are available in quantities of two, six or 20. A card of 20 costs $21.50, said Co-op store manager Mark Sours.

The Co-op in Carbondale also carries a product called Vectolex, a granular substance that contains a different bacteria, Bacillus sphaericus. Vectolex is applied to larger areas of water, and five to 10 pounds of the substance is required per acre of water. It is sold in 40-pound bags at $240 per bag.

A third product available at the Roaring Fork Co-op is called Mosquito Free. This is a very different type of product, designed to break the surface tension of still water so that mosquitoes cannot land to lay their eggs.

Mosquito Free is available in an 18-ounce pump spray bottle for home use on bird baths and in other such places, at $12.50. It also comes in quarts of concentrate, enough to mix 10 gallons of spray, for agricultural use. Mosquito Free is safe for use in drinking water for livestock, Sours said.

Hy-Way Feed and Ranch Supply, in Silt, carries a doughnut-shaped larvicide product called B.t.i. Briquettes, said Hy-Way owner Leonard Hedberg. These doughnuts, like Mosquito Dunks, contain Bacillus thuringiensis israeliensis, and treat about 100 square feet of water each. They continue to release the bacteria over a long period of time, and sell for about $1 each.

Hedberg said Hy-Way also carries a product called Mosquito Halt, sold as a spray-on insect repellent for horses. (Like humans and certain birds, horses are susceptible to infection with West Nile virus.)

The active ingredient in Mosquito Halt is a chemical insecticide, permethrin.

Richard Knudsen, a warehouse worker at the Silt Co-op, said that store also carries Mosquito Dunks, described above.

All three farm supply stores also carry chemical insecticides such as Malathion and Sevin, used to kill adult mosquitoes.

Contact Jeremy Heiman: 945-8515, ext. 534

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