Studies were done during 1982-1985 to describe the parasitism of stem borers attacking corn (Zea mays L.) and sweet, forage, and grain sorghums (Sorghum bicolor (L.) Moench) in the Lower Rio Grande Valley of Texas. Stem borers studied included Diatraea lineolata Walker, Eoreuma (= Acigona) loftini (Dyar), D. saccharalis F., and Elasmopalpus lignosellus (Zeller). Ten species of parasites were reared from one or more of these stem borers including egg parasite Trichogramma sp. (Hymenoptera: Trichogrammatidae); larval parasites Bracon sp., Orgilus sp., Orgilus gelechiaevorus (Cushman), Cotesia (= Apanteles) flavipes (Cameron), Iphiaulax sp., Allorhogas pyralophagus Marsh, Chelonus sonorensis (Cameron), and Rhygoplitis aciculatus (Ashmead); and larval-pupal parasite Archytas marmoratus (Townsend). The gregarious larval parasite C. flavipes attacked D. saccharalis more frequently than other borers on corn and sorghum, and parasitism of all stem borers was generally very low and ineffective for control.