The Salem witch hunts of 1692 may have initially been caused by an infestation of a microbiological poison. The fungus, Claviceps purpurea, commonly known as rye smut, produces the poison ergot. When ingested, this poison produces symptoms similar to the ones observed in the girls accused of being witches in Salem in 1692. Historians and biologists have reviewed environmental conditions in New England from 1690 to 1692 and have found that conditions were perfect for an occurrence of rye smut overgrowth. The weather conditions during those years were particularly wet and cool. Rye grass had replaced wheat as the principal grain because wheat had become seriously infected with wheat rust during long periods of cold and damp weather. The symptoms of ergot poisoning include convulsions, pinching or biting sensations, stomach ailments as well as temporary blindness, deafness, and muteness.