There are more than 150,000 species of Lepidoptera (butterflies and moths) worldwide and around 2,500 in Britain. As a rule of thumb butterflies are usually brightly coloured day-flying insects, have clubbed antennae and hold their wings vertically above the body at rest. In contrast, most moths are nocturnal, hold their wings flat at rest and have either hair-like or feathery antennae. Lepidoptera have mostly herbivorous larvae (caterpillars), which, depending on the species, are able to eat almost any part of the plant from the root to the leaves, flowers and seeds. Some Lepidoptera are considered to be pests in the garden. Many leaf miners are moth larvae feeding inside the leaf. Butterfly larvae of the Pieridae family are pests of brassicas and moth larvae of the Torticidae are pests of trees, including fruit trees (i.e. codlin moth, Cydia pomonella). However, the majority of British Lepidoptera are not pests.
Moth sexes communicate using odours (pheromones). Bolas spiders mimic female moth pheromonesto lure male moths to their death.
Some male butterflies, having mated, will plug the female's genitalia with a sticky secretion to prevent other males from fertilising her eggs.
Some species of noctuid moth have switched from eating fruit juice to mammalian blood, making them vampire bats.