A LECTURE given by Dr. T. Swarbrick to the Royal Society of Aris, on January 26, described, inter alia, some interesting features of the use of petroleum oils per controlling the pests of fruit trees. One difficulty about their use was an occasional phyto-toxic effect. The chemists of the Royal Dutch Shell Group have now traced the cause of this damage, and found methods for its removal. Earlier work by Chapman and Pearce indicated the necessary conditions of boiling point and viscosity which conferred insecticidal action. Petroleum can also be used as a total or selective weed-killer, and new methods of application are designed to reduce the amount of water required in spraying. Atomized oil sprays may need no more than 2¼ gallons of spray fluid per acre for crops of small fruit.