US Cotton Almost Clear of Voracious Boll Weevil

This photo provided by Texas A&M University shows a boll weevil trap that allows cotton producers to...

This photo provided by Texas A&M University shows a boll weevil trap that allows cotton producers to monitor the whereabouts of the pests. For more than a century, the small green beetles ate through U.S. cotton crops, costing growers $20 billion and making the boll weevil the most expensive agricultural pest in the nation's history. (AP Photo/Texas A&M University)

(AP)

For more than a century, small green beetles ate through U.S. cotton crops, costing growers $20 billion and making the boll weevil the most expensive agricultural pest in the nation's history.

But finally, good has prevailed over the weevil.

U.S. agricultural officials declared victory this year in a decades-long effort to exterminate the boll weevil. About 98 percent of the 9 million acres of cotton planted this year were free of the pest, and it has been wiped out in four more states: Arkansas, Missouri, Tennessee and Mississippi.

Infestation remains in only parts of Texas and Louisiana, and officials have high hopes for clearing those areas as well.

"It's really satisfying to be able to measure the progress over the years," said Bill Grefenstette, head of the national eradication program at the U.S. Department of Agriculture's Animal and Plant Health Inspection Service.

The boll weevil spread from Mexico to Texas in the early 1890s. Breeding prolifically and able to fly up to 60 miles on its own, it ploughed a destructive path across the Cotton Belt and into southern Virginia by the 1920s.

With the boll weevil destroying about 8 percent of the annual U.S. cotton crop and many growers going out of business, farmers in the South began to diversify. They also turned to science for help.

The U.S. Department of Agriculture set up a boll weevil research lab at Mississippi State University in 1960. Researchers drew up a strategy based on the U.S. cattle industry's success in using sterile males flies to get rid of the screwworm.

First, fields would be sprayed with a pesticide, most often malathion, to control the pest. Then, insecticide-laden traps baited with the pheromone, or scent, that boll weevils give off when they want to mate would be laid in fields. The smell lured the bugs to their deaths.

When farmers spotted large numbers of boll weevils in traps, they targeted those areas with more insecticide.