If insects inherit the earth – and given our present fecklessness it seems entirely possible that they will – one reason may be the extraordinary process known as metamorphosis. As Kim Todd points out in her introduction to this brisk biography of the German painter Maria Sibylla Merian, who gained fame for her almost hallucinatory studies of natural subjects, insects are already the most successful of living creatures. A million species are known; another four or five million, it is estimated, are yet to be discovered. Their most powerful advantage over the rest of creation is their ability to take on radically different forms at different stages of life, thus reducing competition for food and space. A leaf-eating, earth-bound caterpillar transforms itself into an aerial butterfly living on nectar, a maggot turns into a fly: this is metamorphosis.