Japanese beetles overwinter in the soil as the third larval stage and, as the soil warms, move closer to the surface to feed on fine rootlets. Females burrow into loose, moist sod to deposit eggs. The eggs hatch after a few weeks and the grubs feed on rootlets until cold weather arrives. Most grasshopper species pass the winter as eggs, laid in masses up to two inches below the soil surface. Containing as many as 120 elongated eggs, these are mainly deposited in field margins and roadsides, but may also be laid in legume or grass fields.
Spider mites overwinter as adults in fencerows and woodlots.
They move into edges of the field in the summer, developing small colonies on the undersides of leaves. Spider mites are very small and are frequently blown from plant to plant. Eggs, nymphs and adults may all be found on the undersides of leaves at the same time. They withdraw plant juices with their sucking mouthparts and are particularly abundant during hot, dry conditions. Damage Emerging bean leaf beetle adults feed on the cotyledons, unifoliate and trifoliate leaves of small soybean plants, sometimes completely defoliating the plant.