By spending a little bit of money now you can save yourself money later in the season. Worms have been particularly bad in both soybeans and peanuts the last few years. For us we normally see green clover worms, velvetbean caterpillars and loopers.
All will feed on the foliage and if populations reach high enough numbers they can begin to damage pods as well. I have never seen a soybean field that needed insecticides applied late for worms as long as the producer put out Dimilin at full bloom.
Our most troublesome worm of the ones mentioned above is the velvetbean caterpillar. Dimilin is very good at controlling this and the green cloverworm. It will not, however, control loopers or armyworms. So you may see some feeding damage on the leaves.
Since we do not recommend spraying for worms until 30% of the foliage is eaten, controlling velvetbean usually keeps us below the threshold. Even if loopers are present in the field. Dimilin provides good residual control of velvetbean so one application should be all you need.
While going over the field you may want to add some boron to help with pod set and a pyrethroid if you have any other pests like kudzu bugs or three cornered alfalfa hoppers.
Contact you County Agent if you have questions.