The spray-tunnel application method was adapted for fast determining of the contact toxicity of insecticides to bark beetles. The Douglas-fir beetle (Dendroctonus pseudotsugae Hopk.) was used as the test insect. The relative contact toxicity of 10 test insecticides at the LD50 and LD90 levels, listed in decreasing order, was as follows: at LD50: Lindane>Thiodan®(6,7,8,9,10,10-hexachlor-1,5,5a, 6,9, 9a-hcxahydro-6, 9-methano-2, 4, 3- benzodioxathiepin-3- oxide)> isodrin> endrin>Sevin®(N-methyl-1-naphthyl carbamate) > heptllchlor> aldrin and dieldrin> DDT >chlordane; at LD90: Thiodan> endrin > lindane> isodrin> Sevin> aldrin > heptachlor> dieldrin> DDT> chlordane. All insecticides showed greater toxicity to the males than to the females except Sevin, which was more toxic to females. Treated wood fiber surfaces were used for studying the residual toxicity under constant laboratory conditions for a 13-week period. In contrast to the gradual decline in residual toxicity of endrin, Thiodan, and to a lesser degree isodrin, a rapid decrease was shown by lindane, aldrin, heptachlor, and chlordane. DDT exhibited the most gradual decline.