One of the most common microorganisms used in biologically-based pesticides is the Bacillus thuringiensis or Bt bacterium. Several of the proteins produced by the Bt, principally in the coating the bacteria forms around itself, are lethal to individual species of insects. By using Bt in pesticide formulations, target insects can be controlled using an environmentally benign, biologically-based agent. Bt-based insecticides have been widely used by home gardeners for many years as well as on farms.