ScienceNewsline; Biology: According to a new study published in the Journal of Economic Entomology (Vol. 104, No. 6, Dec. 2011) by University of Florida researchers (Lewis et al.), a key amino acid essential for human nutrition is also an effective insecticide against caterpillars that threaten the citrus industry. Namely, Southeast Asian citrus-feeding larvae of Princeps (Papilio) demoleus (L.) were recently introduced into the Americas, causing an imminent threat to citrus production and ornamental flora. In the research the human nutrient amino acid methionine, sprayed on plants, showed toxic effects for larvae, therefore may be a candidate environmentally safe biorational pesticide for use against invasive P. demoleus in the Americas.