Grain-destroying insects, and those which may infect other types of particulate matter, when feeding and moving about, induce vibrations in the grain or particulate material affected which is modified and amplified to an audible level. The detection is performed using a crystal with piezoelectric properties directly and physically connected to a vibratory receiving structure such as an elongated probe, a thin, flat diaphragm or the like which mechanically amplifies the vibrations to the crystal. The vibratory sounds are then analyzed, such as by comparison with other records of known destructive insects to determine the probable species of insect and its location.