Approximately 40,000 stemborer larvae, pupae, and parasite cocoons were collected during 1982–1995 from commercial sugarcane fields and allowed to complete development under laboratory conditions. Eoreuma loftini (Dyar) and Diatraea saccharalis (F.) comprised 92.4% (36,897/39,945) and 5.2% (2,057/39,945) of the stemborers collected. More than 65% of field-collected stem borer larvae completed development and emerged as adults after being transferred to artificial diet; however, 27.5% died during development. Average seasonal parasitization of E. loftini larvae and pupae (including parasites collected during sampling and those that completed development) was 6.2 ± 1.0%. The most numerous parasites collected from E. loftini included 2 indigenous braconids, Chelonus sonorensis Cameron and Digonogastra solitaria Wharton & Quicke, and 2 exotic braconids, Alabagrus stigma (Brulle) [ =Agathis stigmatera (Cresson)] and Allorhogas pyralophagus Marsh. Average seasonal parasitization of D. saccharalis was 8.9 ± 1.6%, caused mostly by Cotesia flavipes (Cameron).