Grasshoppers are always worse in dry years. They tend to move from border vegetation or infield weed sources as they dry down (which occurs more readily in dry weather), or from cover crop after herbicide burn down. They will undergo several generations—we find hoppers in all sizes (nymphs and adults) almost any time during the season, especially as we move into late summer/fall. They will eat soybean leaves, but are also capable of feeding on young pods later in the year. Treatment this time of year has to be based on the extent of defoliation. Under normal growing conditions, soybeans are capable of withstanding a lot of defoliation (30-40%) in the vegetative growth stages because they are growing so rapidly constantly putting on new canopy. Of course under these dry conditions, they are standing still, almost. You have to gauge the need for treatment on this tough decision point and it is often a seat-of-the-pants call, as many of them are. If the defoliation is severe and hoppers are abundant, I think you need to consider a treatment. Treating field edges can be effective, especially if hoppers are still moving in from bordering weed sources. If we do not get rain enough to make a decent crop, control efforts and the $ spent will have been wasted—a hard call to make If treatments are made, our limited experience showed that products containing chlorpyrifos (Lorsban 4E at ½ to 1 pt/acre, or Cobalt at 7 to 13 oz/acre) were more effective than pyrethroids. All things considered, I would use the lowest labeled rate. Also, Lorsban 4E is pretty good for controlling twospotted spider mite, which may also be present, or at least a pending threat.