The persistence in soil of lindane, dieldrin, chlordane, aldrin, and heptachlor applied as single sprays to the surface of grassland was studied at 4 locations in Nova Scotia to 13 years after application. Lindane was not detected 12 years after application. Dieldrin and chlordane were the most persistent of the applied insecticides; about 25% of the initial applications remained. Aldrin and heptachlor were completely converted to their epoxides. Fall applications of insecticides resulted in larger residues than spring applications. Over 80% of the total residues were found in the 0 to 4-in. depth, but traces had penetrated to the 8 to 10-in. depth in some plots. Effectiveness of these insecticides in wire worm control is discussed in relation to residues found in this study.