Six groups are joining the Utah Agriculture Department in an effort to kill off an infestation of Russian wheat aphids without endangering wildlife, farm animals or humans, the state agency says.

The tiny aphids have been attacking Western grain fields for several years, but they had not appeared in Utah until last summer, in Box Elder County, department spokesman El Shaffer said.Because the insects are virtually immune to Utah's winter weather, several Box Elder farmers last month sprayed their fields with the pesticide di-syston in efforts to wipe out the pests.

But, because of the possible threat di-syston poses to wildlife and domestic animals, the state has started "a joint effort to create a safe pest-control program for next spring," Shaffer said.

The Utah State University Cooperative Extension Service and Agricultural Experiment Station, Utah Wildlife Resources Division, Utah-Idaho Farmers Union, Utah Farm Bureau Federation, Utah Wool Growers and U.S. Fish and Wildlife Service have joined the department in the aphid control program.

"Russian wheat aphids are capable of reducing wheat and barley yields by as much as 50 percent," said Jay Karren, a USU Extension Service entomologist.

"Up to now, chemicals are the only known way to control the aphids, and di-syston is the most effective pesticide available," Karren said. "It is cleared for use on both wheat and barley, and current research indicates residues do not build up in animals' and birds' bodies to endanger humans."

But the state said the chemical insecticide may harm wildlife, especially game birds and animals feeding in treated fields, Shaffer said.

"Wildlife Resources Division officials will work with USU Extension Service and Utah Agriculture Department personnel to schedule chemical control on grain fields next spring at times that will minimize the danger to wild animals and birds," he said.

A committee representing the interested groups "will draw up recommendations for application times," Shaffer said.