Reports of tests of new insecticides have tended to minimize the practical dangers to beekeeping when these toxicants are applied to crops in bloom. The idea is current that these insecticides are harmless to bees if applied during hours when bees are not on the field. An examination of one alfalfa-seed area, where bee losses from commercial applications were reported, prompted a more critical examination to determine the effect of field applications of these insecticides on bees. This paper is a report of field experiments near Logan. Utah, with early-morning applications of DDT, chlordane, parathion, and toxaphene to alfalfa in flower.
Todd, Frank E.; Lieberman, F. V.; Nye, William P.; and Knowlton, G. F., "The Effect of Field Applications of Insecticides on Honey Bees" (1949). All PIRU Publications. Paper 788.