and water, methods of mass rearing of experimental animals and also marking methods are all discussed, as are threshold limit, critical number and the prognosis of damage in plant protection. A classification, an identification key and a systematic check-list of both pest slugs and snails and their predators are provided. The book reviews the biology, physiology, metabolism, reproduction and dispersal of freshwater and terrestrial gastropods, and also the ecological factors which allow a population explosion to occur, thus increasing the likelihood of damage to crops, or the spread of worm diseases of man and domestic animals. The interaction of parasitic worm larvae and their snail hosts is also discussed. These aspects all form an essential basis for the resolution of problems of control.