Inventing 'Gaichu' (Insect Pests): The Emergence of Economic Entomology in Japan

Akihisa Setoguchi, Economics, Osaka City University

Abstract
This paper addresses how the introduction of modern entomology radically changed the view of insect pests in Japan. As early as the eighth century, outbreaks of insect pests were reported in Japan. In the seventeenth century, whale oil was used as an insecticide, a technique probably learned from China. Although the method of spraying oil was well known by the early nineteenth century, most Japanese farmers did little or nothing to deter insect pests. Most just prayed to the gods or performed a religious ceremony called 'Mushi-okuri' (insect expulsion). They believed it was impossible to control insects because they were generated from humid air in a process of spontaneous generation. There was not even a word for 'insect pests' before the late nineteenth century. The word 'mushi' (insects) was used for harmful insects. After Japan developed into modern country, the word 'gaichu' (insect pests) became popular. In 1885, the Japanese government passed a law forcing farmers to control insect pests. The government established the Imperial Agricultural Station and introduced economic entomology in the 1890s. Academic entomological laboratories were also established at the Imperial University in Tokyo and Sapporo Agricultural College. However, it was Yasushi Nawa (1857-1926), a non-academic entomologist, who changed the Japanese view of insect pests. He established a private entomological laboratory in 1896 and worked strenuously to educate farmers to see insect pests as controllable. As a result, every farmer in Japan began to use scientific methods to control gaichu.

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