Root weevils are a serious pest of ornamental trees, barriers, and grass. Both the adult and larval stages of the black vine weevil and root weevil cause damage. The adult weevils generally feed at night, chewing the edges of the tree or plant’s leaves. In the summer, the females lay hundreds of eggs in the soil at the base of plants. As the juvenile white grubs emerge they begin to eat the lower foliage or burrow deeper into the soil to feed on the roots. The grubs over-winter in the soil and emerge the following spring to resume feeding. Most plant damage is caused during the spring feeding. In the case of trees and shrubs, the most harmful damage is done when the grubs feast on the ends of the roots and prevent large trees from taking up adequate moisture and nutrients.
Since the grubs are normally protected by the soil, most control steps are focused on controlling the adults before they mate. As soon as the adults emerge from the soil, spray all the plants and grass in the area with Bug Buster Pyrethrin Insect Spray. Repeat the spray every ten to fourteen days.
In cases of large infestations attacking mature trees, apply the Once-A-Year Insecticidal Drench w/Merit early in the spring to help protect the roots against feeding by the grubs.