Mass rearing of the sugarcane borer, Diatraea saccharalis (F.), was attempted on a limited scale in the laboratory. Larvae were cultured in cotton-stoppered Erlenmeyer flasks containing sugarcane tops or an artificial agar-base diet. Rearing was done under aseptic conditions. From a series of experiments in which the amounts of each ingredient in an artificial diet called the "standard diet" were varied, an "improved diet" was formulated. This improved diet contained corn plant powder (an acetone extract from corn plants, 10.0 grams), sucrose (5 grams), cholesterol (0.2 gram), Wesson''s salts (1.0 gram), yeast extract (2 grams), Bacto-agar (3.5 grams) and distilled water (125 milliliters). Results from several experiments indicated that the optimum amount of sugarcane tops for mass rearing should be 15 grams per insect, and that 7 1/2 grams per insect of the improved artificial diet should be adequate for the complete development of sugarcane borer larvae. Ten insects were reared in each 250-milliliter Erlenmeyer flask containing the sugarcane tops. Sugarcane tops appeared to be slightly superior to the improved artificial diet for rearing sugarcane borers.