Triple threat: Three insects ones to watch in 2005

The soybean aphid, western corn rootworm beetle and European corn borer are just three of the insects that Indiana farmers will have to be on the lookout for this year.

First detected in Indiana in 2000, it seems that the soybean aphid is here to stay, said Larry Bledsoe, Purdue University Cooperative Extension Service specialist.

Bledsoe said that aphid numbers have alternated between high and low for the last five years. If the pattern holds, this year's aphid numbers are expected to be high. More aphids also should mean an increase in the number of Asian lady beetles, because these beneficial insects feast on aphids.

It is important that farmers not "piggy-back" an insecticide for aphid management with other sprays solely for the sake of convenience, Bledsoe said.

"If an insecticide is sprayed for potential control of aphids early in the growing season only for convenience, it may result in a reduction of the Asian lady beetle, an important predator of the soybean aphid," he said.

Reducing the early-season beetles and other beneficial insects may result in an even larger increase in the soybean aphid's economic impact later in the growing season, Bledsoe said.

Indiana farmers also should be watching for the western corn rootworm beetle, particularly in northern Indiana. Results from a statewide survey last year suggest that farmers in northwest Indiana are at very high risk for damage from the corn rootworm beetle. Northeast and east-central counties and those immediately south of I-70 are at moderate risk, and the rest of southern Indiana is at low risk.

"Growers also should not become complacent about the European corn borer," Bledsoe said. "Although numbers have been relatively low for the past eight to 10 years, the probability of a statewide outbreak increases with each year."

The larvae of the corn borer feed on corn leaves, causing holes. Corn borers also move down the stalk and bore into it, weakening the plant and allowing for stalk breakage later in the season. The insects' presence also can stunt corn growth.

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