Laboratory bioassays were conducted to establish baseline toxicity data for Pirate (AC303,630) and Spinosad (DE-105) on tobacco budworm and bollworm in 1991-92. In a leaf dip bioassay, Pirate LC50's were slightly higher (1.5-2.5x) than a cypermethrin LC50 observed for a laboratory (LSU-LAB) tobacco budworm colony. In a topical diet study, LC50 values of several field collected tobacco budworm colonies exposed to Pirate ranged from 18.8-38.2 ppm, a 2.0x level of variation. The Pirate LC50 for a laboratory (Stoneville) colony of bollworm was generally lower than LC50's for laboratory and field tobacco budworm colonies. In larval topical tests, the range of Spinosad LD50's among several tobacco budworm colonies ranged from 0.4-8.5 mg/g (21.4x level of variation). A series of small plot field tests conducted in Louisiana during 1989-95 evaluated the efficacy of Pirate and Spinosad against tobacco budworm, bollworm, soybean looper and beet armyworm. In these tests, Pirate and Spinosad generally provided control of Lepidopteran pests equal to or greater than that afforded by pyrethroid, organophosphate and carbamate standards.