The southern potato wireworm, Conoderus falli, became resistant to aldrin and heptachlor in the Hastings, Florida area during the years from 1955 to 1958. Diazinon and parathion were recommended for wireworm control in 1959 and have been successfully used since that time. Laboratory tests of wireworms collected from 5 different locations in 1961 and 1962 showed that the southern potato wireworm was very susceptible to soil treated with parathion at the rate of 1 and 2 pounds actual per acre to a depth of 6 inches. Resistance to aldrin at 4 pounds actual per acre by the wireworm is well developed and has not appeared to diminish after 4 seasons of nonuse. Differences in susceptibility to the insecticides by wireworms from different locations were not evident.