This book offers an introduction to the biology and identification of the larvae of the Cecidomyiidae. The family does not only consist of well known gall-makers, among which many species of economic importance occur, but also of many soil-dwelling and mycetophagous species with very peculiar habits like paedogenesis (larva-producing larvae). Subjects such as trophic habits - mycetophagy, gall inducing and zoophagy - specialization on food resources, reproduction, paedogenesis, larval development, larval mobility, induction of diapause and pupation are subject of a chapter on biology. A chapter considering morphology presents a survey of larval characteristics and comparative morphology. The main body of the book consists of identification keys and descriptions of those gall midge species which pass at least some phases of their life-cycle (larval and/or pupal stages) in the soil. The original Russian version of 1965 was a landmark in gall midge studies. The present edition makes the book accessible to non-Russian biologists. With some additions by the editor to update the taxonomy and terminology, the book is indispensable for students of Diptera, soil biologists, ecologists and evolutionary biologists.