Grain sorghum is most susceptible to stink bugs in the milk and soft dough stages. Once the grain is hard, susceptibility to stink bug damage is greatly reduced. All adult stink bugs are shield shaped. When immature stink bugs first hatch, they have a black head and thorax, but the abdomen is red with two black spots. The immature form is light green with a series of white spots along the back.
Check fields weekly for stink bugs after heads begin forming.
Examine 50 to 100 heads throughout the field to determine the average number of stink bugs per head. Treatment for stink bugs should begin when stink bugs per head average five during flowering, milk and soft dough stages. During the hard dough stage, treat when 16 or more stink bugs are present per head. Insecticides for Control of Stink Bugs on Grain Sorghum. Each pest is a problem during the stage of plant development under the line above its growth stage.