A continuous line of a toxic dust approx. 1 inch wide applied on a smooth surface between infested grain fields and corn was effective in controlling chinch bugs (Blissus leucopterus) by killing all nymphs and adults that attempted to cross the line. Exptl. barrier lines of dinitro-o-secondary butyl phenol, 3-5-dinitro-o-cresole and dinitro-o-cyclohexyl phenol in concs. of 2, 4, 8 and 12% in pyrophyllite, applied at the rate of 1/4, 1/2 and 1 1b. per linear foot of barrier line, were all effective. Laboratory tests show that 1% dusts kill chinch bugs in <1 hr. 8% dusts of the NIL, Na and dicyclohexylamine salts of all 3 compounds were highly toxic to chinch bugs. 100% kill was obtained in 1-6 hrs.