In a random-block expt. of six 6-row, 0.05-acre plots per treatment conducted on summer-planted sugar cane during Sept. and Oct., 1946, the herbicide 2,4-dichloro-phenoxyacetic acid, applied twice as a dust at 14-day intervals at the rate of 1 pound of the acid per acre, gave an increase of 44% in the sugarcane borer (Diatraea saccharalis) population over untreated check plots. In plots where 1 lb. of 2,4-D per acre was added to synthetic cryolite in 2 of 4 weekly cryolite applications, the borer population was 38% greater than in plots receiving cryolite alone. In plots where 1 lb. of 2,4-D per acre was added to 50% Na fluosilicate in 2 of 4 weekly applications, the number of borers was 85% greater than in plots receiving Na fluosilicate alone. The sugarcane plants were examined for borer eggs and egg parasitism by Trichogramma minutum at the completion of dust applications. The average numbers of eggs found per plot was 281 in the treated plots and 230 in the untreated plots, and the av. % of parasitization was 49 in the treated plots and 60 in the untreated plots.