One of the last things a peanut grower wants to do is make an insecticide application in late September, and it is one of the last things that I want to recommend. We still have fields in Georgia with velvetbean caterpillar (VBC) infestations, and populations in some fields are high. The question that we get is what to do when a field has a large number of large caterpillars and it is time to dig. Will those caterpillars feed on pegs once the peanuts are inverted? Unfortunately, there is no way to know what will happen. I have seen plenty of fields that were dug with active velvetbean caterpillar infestations, and there was little or no peg or pod feeding between digging and harvest. On the other hand, large caterpillars are not just going to give up and die after peanuts are inverted. They will continue to feed (or try to) until there is no suitable food left. The choice will come down to each grower and his tolerance for risk. Digging a field with 5 large caterpillars per foot of row would make nervous. There are no data or published studies to help us make the decision to treat. Significant peg and pod feeding in inverted peanuts is not common, but it can happen, and growers need to be aware of the risk.
Controlling velvetbean caterpillar immediately before harvest is one of the places where pyrethroids can have a fit in peanut insect management. As long as VBC populations remain susceptible, pyrethroids offer rapid knockdown for a relatively low price. Check the pre-harvest interval on insecticide labels to choose the product that provides the best fit.