A procedure for screening residual insecticides applied to soil in the laboratory has been perfected. An evaluation of some of the chlorinated hydrocarbon insecticides commonly used in controlling other soil-inbabiting insect pests revealed the fact that a few of these have appreciable biological activity against the eye gnat, Hippelate. collusor (Townsend). These materials with a high degree of activity are Shell Compound SD-4402 (1,2,3,4,5,6,7,8,8-Octachloro-3a,4,7,7a- tetrahydro-4,7 -methanophthalan), DDT, and endrin. Shell Compound SD-4402 gave 98% reduction of the emerging gnats when applied at 2.5 pounds Actual material per 6-inch acre (1 acre surface area 6 inches deep). DDT at 18 pounds actual material per 6-inch acre gave 80% while endrin at 5 pounds actual material per 6-inch acre gave 80% reduction of the emerging eye gnats from the treated soil. Aldrin, dieldrin, heptachlor, lindane, Compound GC-1189 or Kepone® (1,2,3,5,6,7,8,9,10,10-Decachlorotetracyclo [5.2.1. 02,6.03,9,05,8] decan-4-one), toxaphene, and chlordane yielded poor results when applied at moderate dosages (4 to 20 lbs. per 6-inch acre). Granulated formulations of DDT, particularly the higher percentage formulations, were found to perform poorly as compared with spray applications. Upon aging for 3 months, the effectiveness of 20% and 35% granulated formulations on attapulgite granules increased somewhat but did not equal that of DDT sprays. Ten per cent granulated formulations manifested increased effectiveness on aging and proved to be as effective as sprays after 3 months' aging. The biological activity of aldrin and dieldrin decreased when these materials were aged in soil for 3 months; that of DDT and endrin remained the same. The activity of toxaphene increased upon aging for S months, but the overall activity of this chemical against the pest was very low.