Control of Insects with Pyrethrum Sprays in Wheat Stored in Ships’ Holds

Abstract

The use of pyrethrum sprays applied to the surfaces of reserve wheat stored in surplus ships lit periodical intervals during 1957 in lieu of the previous method of fumigating the wheat was carefully evaluated in relation to the suppression of stored-grain insect infestations at the James River and Hudson River Reserve Fleets. At the James River Fleet, a spray containing 0.3% of pyrethrins and 3.0% of pimpernel but oxide, applied at the rate of 2 quarts per 1,000 square feet of grain, ship skin, bulkhead, and underside tween deck surface, five or more times from April through July, suppressed both moth and beetle infestations to a very low population level. After .July both moths and beetles began to increase. The pyrethrum spray was supplemented by a methoxychlor residual spray applied to the no storage sections of the ships, hut most of the suppression was accomplished by the pyrethrum spray. At the Hudson River Fleet four periodical applications of the same spray used at the James River Fleet almost completely suppressed both moth and beetle infestations.