An Investigation of Sulfur as an Insecticide

Abstract

The toxicity of sulfur and some of its compounds was tested under laboratory and field conditions. Atmospheres containing the volatile products of lime-sulfur were found to produce lethal effects on San Jose scale (Aspidiotus perniciosus), especially on the young. Tests on the covers of this species indicate that they are very slightly, if at all, soluble in lime-sulfur and the common wax solvents such as benzene, xylene and turpentine. Three new sulfur insecticides were invented during the progress of this investigation. (1) Carbon disulfide-sulfur emulsion was made by emulsifying soap and water with carbon disulfide containing dissolved sulfur. Promising results were obtained with this preparation in the control of pear psylla (Psylla pyri) and as a dormant spray for San Jose scale. (2) Sulfur-naphthalene dust was preparcd by dissolving flowers of sulfur in melted naphthalene, then rapidly chilling the solution and grinding the solid thus formed into a dust by means of a ball mill. As a greenhouse insecticide this dust has proved effective against red spider (Tetranychus sp.) and aphids. (3) A colloidal sulfur was prepared by passing sulfur fumes into a dispersion medium, such as soap and water or glue and water. This method of manufacture has an advantage in that it obviates the necessity of changing the sulfur to some other form and recovering it again by chemical means. Field tests indicate that this preparation compares favorably with other colloidal sulfurs in the control of insects and apple scab.