Pederin is a vesicant toxic amide with two tetrahydropyran rings, found in the haemolymph of the beetle genus Paederus, including the Nairobi fly, belonging to the family Staphylinidae. It was first characterized by processing 25 million field-collected P. fuscipes. It makes up approximately 0.025% of an insects weight (for P. fuscipes). It has been demonstrated that the production of pederin relies on the activities of an endosymbiont (Pseudomonas ssp.) within Paederus.