Spinosyn A 17-pseudoaglycone is an acid degradation product produced by selective hydrolysis of the more labile forosamine saccharide in the 17-position of spinosyn A, the major component of the commercial product, Spinosad. Spinosyn A 17-pseudoaglycone is only weakly active as an insecticide as the forosamine moiety is considered essential for potent activity. Despite the importance of spinosyns as agro-chemical insecticides and more recently as animal health products, there are few published reports of the biological activity or the levels of spinosyn A 17-pseudoaglycone in animals or in the environment.