AceCap Insecticide Systemic Tree Implants, 3/8-inch Implant Diameter (10 Pack) Acecap Systemic Insecticide Implants, contains environmentally acceptable acephate Each implant is 3/8-inch diameter - For 4in. spacing, use 3/8in. diameter drill bit to drill 1-1/4in. deep from the cambium surface Do not use for trees less than 3in. DBH (Diameter at Breast Height, about 4ft. from ground) Testing proves that Acecap implants prevent and control Emerald Ash Borer Do not use on fruit, nut, or syrup trees that will be consumed or sold - Use on ornamental trees