Abstract This review article starts with the discovery of Bacillus thuringiensis Berliner in Japan at the turn of the century and notes that the observations of the early Japanese workers clearly show that they were aware of the toxin-mediated nature of the activity of B . thuringiensis toward insect larvae. The early work in Europe with B . thuringiensis against Ostrinia nubilalis (Hubner) showed that the bacterium had promise as a microbial control agent. The commercial development of B . thuringiensis in France in the late 1930s, and in Eastern Europe and the United States in the 1950s, is traced.