Damage is heaviest in cool, wet springs when emergence is delayed. Recent problems in Kansas seem to be most serious where heavy rates of liquid or solid livestock manure have been spread on the field just before planting or where soybeans are planted in no-till situations.
Dig into the soil around newly planted seeds to observe them feeding on seed if present.
No recommended threshold.
None.
This information comes from the Kansas State University Agricultural Experiment Station and Cooperative Extension Service publication MF743. Information may not be suitable for states other than Kansas.
Some planter box seed treatments containing permethrin (Kernel Guard Supreme or KickStart VP) are labeled for controlling these pests in soybeans. In addition, the seed treatments thiamethoxam (Cruiser 5FS or CruiserMAXX) and imidacloprid (numerous products) are labeled for protecting soybeans. Follow label directions and DO NOT use leftover seed for food, oil, or livestock feed.