Ash (Fraxinus spp) trees on the Michigan State University's campus have been injected with insecticides since 2005 to protect against the emerald ash borer Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). Annual applications of imidacloprid and bi- to tri-annual applications of emamectin benzoate have been the primary chemicals used by the university, with emamectin benzoate becoming the primary chemical used in 2013.Imidacloprid was the cheapest chemical to apply but must be applied annually and efficacy can vary. Emamectin benzoate was the most expensive chemical to apply, but the costs were annualized across two to three years, reducing the initial cost. The condition of the ash population improved as trees were protected from year to year with the ash population having an overall low percentage of canopy dieback and transparency. Ecosystem services were quantified via i-Tree Eco, which valued the ash population at nearly 10 times the total cost of treating the ash trees.Alternate management strategies were simulated: 1) remove and replace all ash; 2) treat 2265 20 cm, remove and replace trees < 20 cm; and 3) treat all trees with emamectin benzoate on a four-year rotation. When compared to the current management strategy, the cheapest option was to treat all ash trees on a four-year rotation of emamectin benzoate and the most expensive option was the removal and replacement of all ash trees..
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