Spinosad is an insecticide based on chemical compounds found in the bacterial species Saccharopolyspora spinosa. The genus Saccharopolyspora was discovered in 1985 in isolates from crushed sugarcane. The bacteria produce yellowish-pink aerial hyphae, with bead-like chains of spores enclosed in a characteristic hairy sheath. This genus is defined as aerobic, Gram-positive, nonacid-fast actinomycetes with fragmenting substrate mycelium. S. spinosa was isolated from soil collected inside a nonoperational sugar mill rum still in the Virgin Islands. Spinosad is a mixture of chemical compounds in the spinosyn family that has a generalized structure consisting of a unique tetracyclic ring system attached to an amino sugar (D-forosamine) and a neutral sugar (tri-Ο-methyl-L-rhamnose). Spinosad is relatively nonpolar and not easily dissolved in water.

Spinosad is a novel mode-of-action insecticide derived from a family of natural products obtained by fermentation of S. spinosa. Spinosyns occur in over 20 natural forms, and over 200 synthetic forms (spinosoids) have been produced in the lab. Spinosad contains a mix of two spinosoids, spinosyn A, the major component, and spinosyn D (the minor component), in a roughly 17:3 ratio.