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Issue No. 15, Article 2/July 15, 2011

Other Entomological Observations

Japanese beetles. Both trap captures (pmn.ipm.illinois.edu) and observations of Japanese beetles have increased in several locations across Illinois through early July. Both corn and soybean fields should be regularly monitored for injury. Remember that Japanese beetles often concentrate along field margins; don't base your management decisions on end-row scouting. Thresholds for Japanese beetles in soybeans rely on defoliation levels (30% before bloom, 20% between bloom and pod fill), whereas in corn they depend primarily on numbers of beetles (3 or more per ear and pollination not complete) and level of silk clipping. In drier areas of the state, the intensity of silk clipping will need to be monitored very carefully. Visit the IPM web site for more on the life cycle, biology, and management of Japanese beetles.

Soybean aphids. Soybean aphid densities remain at low levels in much of the north-central region and Illinois. Russ Higgins, commercial agriculture extension educator in the DeKalb Research and Education Center, reported his first observation on July 11 of a soybean aphid in sentinel plots in Grundy County. I know that others have found soybean aphids in a few other locations in northern Illinois, but overall the densities have remained low. I suspect the very hot weather as well as severe storm activity and heavy precipitation in some northern Illinois counties may be responsible.

Regional suction trap captures as reported by David Voegtlin, retired entomologist, Illinois Natural History Survey, also have been low this season. If the very hot weather persists, aphid densities will likely continue to be suppressed, but there is still time for them to surge, so continue your monitoring efforts. This will be especially important if we trend toward cooler summer temperatures at some point.

Western bean cutworms. Our trapping cooperators in Illinois have not reported significant captures of western bean cutworm moths. Entomologists at Purdue University also have reported that the number of moths caught in pheromone traps is well below 2010 levels so far this season. It may still be worth monitoring fields for western bean cutworms, especially if a non-Bt hybrid has been planted. Visit the IPM web site for details on the life cycle, biology, and management of western bean cutworm.-Mike Gray

Author:
Mike Gray

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