Horticultural Oil, or Stylet-Oil, has proven to be one of the best and safest products with maximum insect control for the Adelgid, mites, aphids and many other insect pests. Oil kills by suffocation rather than by poisoning, and insects cannot become resistant to it. In addition, oil sprays are not harmful to humans, wildlife or the environment. Boston Tree Preservation's Horticultural oil also includes a mixture of calcium, colloidal minerals and micro and macronutrients. These minerals and nutrients help maximize the control of insects. The horticultural oil has a residual of several months.