THE Complete Book of Cacti and Succulents by Terry Hewitt (Dorling Kindersley, pounds 15.99) says that slugs and snails 'feed on leaves and fleshy stems . . . To eradicate persistent offenders, scatter slug pellets between the plants or apply a preparation based on aluminium sulphate.' An A-Z plant catalogue forms the chief part of this beautifully produced book but there is a useful section on ways to use succulents and cacti inside and out.