The thing is, aphids adapt.

A good chemical control may be effective for just a few years, said Mike Smith, K-State Research and Extension entomologist. Wheat and sorghum growers learned this first-hand from the greenbug (aphid).

Beyond that, new types of aphids can appear almost overnight, as they adapt to areas far from their home territory. A case in point is the Russian wheat aphid, a native of the Middle Eastern area where wheat -- and perhaps humans -- first developed centuries ago.

"We don’t know how much damage the pest does now in Iran and Iraq," Smith said. "But the Russian wheat aphid got its popular name because it’s also been a pest in Russia since the early 1900s, sometimes reducing the harvest there by up to 75 percent."

Experts suspect grain or hay shipments took the insect to South Africa, where it has developed into a major problem since 1978. Reports now put the pest in Kenya’s highland barley fields, as well.

No one’s quite sure how the "Russian" aphid arrived in central Mexico during 1980.

Nonetheless, it was showing up as far south as Argentina, as far north as North Dakota, and as far west as the California coast by 1986. The pest was in three Canadian provinces three years later.

"So far, Russian wheat aphids appear to be staying in high, dry areas similar to their native habitat on the east end of the Mediterranean," Smith said. "That’s why they’re a U.S. pest only from the West Coast through the western halves of Texas, Oklahoma, Kansas, Nebraska and South Dakota."

Even if they never adapt further, however, they’re already costing U.S. wheat growers an estimated $65 million a year, he said. About 10 percent of the average losses occur in Kansas alone.

"That’s why we need to look at potential savings, when we consider the cost of developing an aphid-resistant wheat," Smith said. "Resistance can not only bring back pre-aphid yield levels but also save the money farmers have been pouring into insecticides, trying to stop a very adaptable pest."

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K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and research centers statewide. Its headquarters is on the K-State campus in Manhattan.