The avermectins are a family of macrocyclic lactones, produced by the soil organism Streptomyces avermitilis, which were discovered in the mid-1970's as a direct result of a screening effort for natural products with anthelmintic properties. Avermectin B1 (abamectin), the major component of the fermentation, also showed potent activity against arthropods in preliminary laboratory evaluations and was subsequently selected for development to control phytophagous mites and insect pests on a variety of agricultural and horticultural crops worldwide. Major applications for which abamectin is currently registered include uses on ornamental plants, citrus, cotton, pears and vegetable crops at rates in the range of 5 to 27 grams abamectin per hectare as a foliar spray. Abamectin has shown low toxicity to non-target beneficial arthropods which has accelerated its acceptance into Integrated Pest Management (IPM) programs. Extensive studies have been conducted to support the safety of agricultural uses of abamectin to man and the environment. Abamectin is highly unstable to light and has been shown to photodegrade rapidly on plant and soil surfaces and in water following agricultural applications. Abamectin was also found to be degraded readily by soil microorganisms. Abamectin residues in or on crops are very low, typically less than 0.025 ppm, resulting in minimal exposure to man from harvesting or consumption of treated crops. In addition, abamectin does not persist or accumulate in the environment. Its instability as well as its low water solubility and tight binding to soil, limit abamectin's bioavailability in non-target organisms and, furthermore, prevent it from leaching into groundwater or entering the aquatic environment.