Japanese Beetles.

An annual insect plague in the farm world is the Japanese Beetle invasion.  They will eat over 200 different plants including most field crops.  Some of the things I have heard they feast on in addition to corn silks and soybean leaves include waterhemp and Virginia Creeper.  Integrated Pest Management for Japanese Beetles says to scout soybeans and spray at a threshold of 30% defoliation.  Corn should be sprayed if silks are clipped to 1/2 inch or less.  Some farmers who spray fungicides mix in insecticides as well for beetle control.  This idea could create resistance problems.  Continue to scout soybeans after spraying because additional invasions are possible.