• A second generation peak of 100+ moths indicates some potential problems, but a peak above 200+ moths should definitely catch your attention. This indicates you already had a fairly successful first generation, and the area at risk will have spread out. Hint – a first generation peak of 20-30 or more moths per week will often result in a second generation peak of > 200 moths. Of course, this would not always be the case if there was not any non-Bt corn in the area for the first generation to get started.
• High moth catches often precede obvious signs of infestation in the field by 7-10 days. So this gives you a little time to react. This is especially important as it is necessary to make any treatments before most larvae have begun tunneling into stalks (making control difficult).
• UT’s standard recommendation is to treat when 20% or more of plants have egg masses or small larvae present.  Unfortunately, it takes some experience and time to scout for corn borers. Depending upon the size of you moth catches and the maturity of the corn, consider insecticide treatment about 7-10 day after you see a sharp rise in moth catches, especially when the peak (or expected peak) is above 200 moths per week. 

There are a number of insecticides recommended for control.  The standard treatment is Intrepid at 4-6 oz/acre.  The synthetic pyrethroids will also provide control and are economical but won’t provide as much residual or rainfastness.  These products include Asana XL, Baythroid XL, Declare, Karate/Warrior, Mustang Max or one of the bifenthrin products such as Brigade, Discipline or Fanfare. There are also some new insecticides that I have tested that also provide excellent residual control including Belt SC at 2 oz/acre and Prevathon (14-20 oz/acre).  Fair warning that there will be some sticker shock with these new insecticides.  However, you might consider them in high pressure areas.  I’ve included some pictures that will help you recognize SWCB (see below and click to enlarge).