<p>Gall midges (Diptera: Cecidomyiidae) are among the most diverse insect families, with an estimated 1.8 million species worldwide, yet only about 7000 have been formally described. In Japan, research on gall midges has a centuries-long history, beginning with early records in the Edo period (1603–1868) and advancing through the Meiji (1868–1912) and Taisho periods (1912–1926) with contributions from both foreign and Japanese naturalists. This review traces the development of gall midge studies in Japan, highlighting key taxonomic and ecological achievements, particularly those led by the late Dr. Junichi Yukawa and his colleagues. I summarize historical and modern research, including pest management in agriculture and forestry, the biology of paedogenetic and predatory species, and recent advances in understanding gall induction mechanisms. Finally, I discuss current research topics and future directions, emphasizing the importance of Cecidomyiidae as a model group for studying insect diversity, speciation, and insect-plant interactions.</p>