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.