Jason from Lehi, Utah writes
How often should I spray if I have a locust borer infestation? Is there another product that would work better to kill locust borers or a systemic product that I don't have to spray?
Fertilome Liquid Carbaryl (Sevin) Garden Spray is not labeled to control locust borers, however GardenTech Sevin Ready to Spray Bug Killer is labeled to treat locust borers. Sevin/carbaryl will only kill insects on contact, and treatments must be at least 7 days apart, with a maximum of four treatment annually for trees and six times annually for ornamental shrubs and flowers.
Systemic insecticides that are labeled for other roundheaded borers should be effective when applied early enough in the season. Fertilome Tree and Shrub Systemic Insect Drench is labeled for roundheaded borers. Zylam Liquid Systemic Insecticide would be an excellent choice if you have a persistant problem or a population that may be resistant to imidacloprid.
This article from your Utah State Extension Service gives more information about this pest.
Answer last updated on: 09/10/2015