They may be tiny, but these mites thrive in hot, dry weather and yellowing and defoliation of corn and soybean leaves. Use a hand lens to check the undersides of leaves, or shake leaves over a white piece of paper.

Southern, Northern, Western ... no matter what region they're from, these beetles spell trouble. Larvae feed on and tunnel into corn roots while adults clip silks. Dig up 10 randomly chosen plants and check roots for worms, or count the number of beetles on five plants in five separate locations.

Don't let the name fool you--this caterpillar is actually a threat to corn. These worms are very mobile and will feed on the leaves, tassel and especially the ears of corn. If you notice the moths in your field, check 20 plants in five locations for eggs and larvae, focusing on the leaves and tassels.

With their metallic green and bronze wings, these beetles are hard to miss. But beware: They'll quickly do a number on your fields by defoliating leaves and feeding on plant roots. Scout by examining five plants in five separate areas of the field, and determine the amount of silk clipping in corn and percentage of defoliation in beans.

Whether they're brown, green or red-shouldered, stink bugs can damage corn ears and soybean pods by sucking the juice right out of them. Scout using sweep nets or drop cloths, or by examining plants directly.