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 stemborer larvae completed development and emerged as adults after being transfered 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).