Last year you identified the willow borer insect on host plat Salix x. rubra aka Harrison's B growing in our willow plot in Sherwood, OR. This year we dug up all the plants by their roots and are now considering replanting the same area with a species that to date, has been resistant to the willow borer at this location. We understand that the willow borer lays its eggs under the bark, then the larvae that emerge tunnel inward and then pupate in the heartwood, exiting the hole as adults. After mating, we understand the adults die and do not remain in the soil. We want to make sure this is correct. If there's a chance there is some stage of this insect remaining in the soil, we'd like to know how to treat it on an organic farm. If there's no chance the borers remain in the soil, then we'd like to replant this area. Thanks for sharing your expertise.