The Black Locust is one of the most valuable of the native trees growing in the United States. Many locust plantations have been started in Illinois, but practically all of them have been destroyed by the Locust Borer, Cyllene Robiniae Forst., in most cases before the trees became of sufficient size to be used even for posts. During the past ten years, many experiments have been conducted to try and find a control for the Locust Borer. These have included most of the recommended practices, and many others. Experiments in poisoning the beetles were carried on for several years, at first with promising results, but in the other years, the results were largely negative. It is shown in the course of this work, that many of the female Locust Borers emerge from the tree, mate, and lay considerable numbers of eggs without having fed. Banding the trees with various materials, particularly tanglefoot showed that the active beetles readily caught in the bands were not killed, and soon freed themselves of most of the tanglefoot. During the past year, bands containing tanglefoot mixed with sodium fluoride and sodium arsenite have killed all beetles coming in contact with them. The sodium arsenite-tanglefoot mixture, seems to offer promise of a practical method of Locust Borer control under certain conditions.