Effect of neonicotinoids on suppression of hemlock woolly adelgid, Adelges tsugae (Adelgidae)

Separate groups of thirty-six hemlock trees were treated with insecticides, dinotefuran, clothianidin, and imidacloprid using a soil injector during spring and fall 2006 at Highlands, NC. Significant suppression of hemlock woolly adelgid was observed for medium and high rates of the insecticide, Safari 20 SG (dinotefuran). Spring applications and fall applications were both effective. Spring applications appear to have given more persistent suppression. The insecticide, Arena 50W (clothianidin) showed intermediate adelgid suppression. Meanwhile, the insecticide, Merit 75WP (imidacloprid) demonstrated a delayed suppression.