Life history and rearing methods are described for Lydella Jalisco Woodley, a recently described tachinid parasite of Mexican rice borer, Eoreuma loftini (Dyar). The parasite was discovered near Ameca, Jalisco, Mexico, parasitizing up to 48% of E. loftini larvae in sugarcane. Extensive surveys of stalkboring pyralids in other sugarcane growing regions of Mexico failed to detect this tachinid parasite attacking E. loftini or any other stalkborer. Female L. Jalisco were attracted to and ovolarviposited on the fresh frass produced by E. loftini larvae tunneling in sugarcane stalks. The preoviposition period averaged 14 d, and number of progeny per female fly ranged from 228 to 534. The planidial 1st instar penetrated host integument through the pleural midintersegmental membranes. Percentage of parasitization was highest on full-grown host larvae (6th instars) under both field and laboratory conditions. In all cases, only 1 parasite emerged from each host. L. Jalisco is a larval parasite; only 5% of the total parasite emergence occurred from host pupae when full-grown larvae were used as hosts. Maggot developmental time decreased as age of host larvae increased, and ranged from 12 d for 6th instars to 19 d for 2nd- and 3rd-instar hosts. Parasite pupal developmental time remained constant (12 d) regardless of host age. Manually placing a single, surface-sterilized, 1st-instar maggot onto a host was the most efficient host infesting technique, yielding an average of 62% (maximum 75%) fly puparia. The placement of groups of surface-sterilized maggots suspended in distilled water on the surface of the artificial diet harboring host larvae yielded an average of 45% (maximum 70%) fly puparia. During dissection of the adult fly to harvest maggots, the bacterium Serratia marcescens (Bizzio) contaminated the maggots and subsequently invaded the E. loftini larva with the fly maggot. Hosts invaded by the bacteria became septicemic, which resulted in a high mortality of hosts. However, septicemia was controlled by surface sterilizing the maggots with formalin before inoculating host larvae. Allowing gravid adult female flies to ovolarviposit on sugarcane stalks previously infested with host larvae yielded only 43% (maximum 63%) fly puparia, but this technique avoided the problem of contamination of hosts with S. marcescens . Field and laboratory studies showed that L. Jalisco is highly specific to E. loftini . The potential of L. Jalisco for biological control of E. loftini and other stalkborers is discussed.