The penetration of insecticidal oils into porous solids

Abstract

Abstract does not appear. First page follows. Many insects and other arthropod pests of economic importance hibernate during the cold season in cracks and cavities in the bark of trees and bushes. Since this occurs when the plants are in a dormant condition and therefore less subject to injury from insecticides, attention has long been directed to the possibility of applying toxic materials to the bark for the control of such pests while they are concentrated in a relatively small area and unable to escape. An example is afforded by the Pacific red spider, Tetranychus pacificus McG., so destructive to grapes in the San Joaquin Valley, which hibernates beneath the loose outside layers of bark on the stumps of grapevines. The range of available insecticides for such use is very wide. However, solids either as water suspensions or as dusts have little chance of getting far enough into the bark. Fumigants are at a disadvantage for two reasons; first, their volatility is low during cold weather; and secondly, the respiratory activity of hibernating insects is very low (Bodine, 1923). This practically limits the choice to contact insecticides such as aqueous solutions of lime-sulfur, nicotine, etc., coal-tar products, either straight or in water solution; and mineral or plant oils, either straight or in water emulsions. By adding other toxic materials which are soluble in one or another of the substances just mentioned a very large number of products of possible insecticidal value can be made.