Next year continue a preventive program of merit between May 15 (for billbugs as well) and then end of July. Must be watered in immediately if you are spraying. For curative, use dylox ( while it's available ) and again water in the application. Diazinon will also do fairly well as a curative. Carbamates ( sevin ) will not give any residual to speak of and will get tied up in the thatch if you have alot.