Effect of Pretreatment on the Toxicity of Insecticidal Films on Building Surfaces

Abstract

INSECTICIDAL films, formed by the deposition of a solution of pyrethrins in a heavy refined mineral oil of very low volatility, for example, Shell Oil P.31, have been used in warehouses for the control of Ephestia and Plodia moths and caterpillars¹. These films were formed on wooden boxes. There has more recently been a considerable increase in scope for the use of such films for controlling other pests of stored foodstuffs, especially beetles, which are more resistant than the moths and their caterpillars to most insecticides, including the pyrethrins. We have found, however, that, other things being equal, the toxicity of films of pyrethrins in a heavy oil differs widely according to the material upon which the insecticide is deposited.