The Action of Certain “Inert” Dust Materials on Parasitic Hymenoptera1

Abstract

Twenty-seven dry powdered materials were examined with respect to their physical characteristics and their mortality to 2 spp. of hymenoptera. Dry materials of mineral origin readily killed the parasites. Those of botanical origin were only slightly lethal despite nearly similar adherence to the insects. With mineral materials mortality was inversely correlated with particle size, but could not be correlated with particle shape. Powders wetted by water mist lost much of their lethal effect; this loss was correlated with the water-sorptive capacities of dusts used. Water-sorption by dust particles is suggested as responsible for parasite kill through desiccation.