Frej Ossiannilsson (December 8, 1908 – March 6, 1995) was a Swedish entomologist who specialized in Auchenorrhyncha, and is known also for discovering vibrational communication of insects.
To bolster the family's income, he secured a temporary position as an assistant at the National Institute of Plant Protection (Institutet för växtskydd).
Working as a general and applied entomologist, Ossiannilsson spent most of the time determining various pest insects, but Auchenorrhyncha as a group remained his specialty.
He performed behavioural experiments with which he demonstrated that vibrations, not sound per se, were involved in male-female courtship, and completed an anatomical study of vibration-producing structures in numerous species.
A study on the morphology and function of the sound-producing organ of Swedish Homoptera Auchenorrhyncha with notes on their sound production (1949).
[1] His contribution to science is now recognized, among others, by the community of biotremologists who established the Insect Drummer Award for esteemed researchers.