Yellow rain. (n.d.). In YourDictionary. Retrieved from https://www.yourdictionary.com/yellow-rain
A powdery yellow substance that was reported in the 1970s and 1980s to drop from the air in Southeast Asia, claimed by the United States to be a fungal toxin used as a chemical weapon by the Soviet Union and later claimed by certain investigators to consist of the excrement of large swarms of bees.