Q What is the difference between a butterfly and a moth? - Michelle Smith, Durham

A For most people, the distinction is simple. Moths fly at night and butterflies fly during the day.

Some might also add that butterflies are usually brightly coloured, while moths are dull and grey.

However some moths are only active during the day and some may be brightly coloured. There are more similarities than differences, since both go through a caterpillar and pupa stage and the winged adults of both have coiled 'tongues' that suck nectar from flowers.

Generally, moths are nocturnal. In other words they prefer to be active during the night while butterflies are diurnal, preferring to fly during the day.

There are, however other more reliable distinctions. One is the antenna. Butterflies have a knob at the end of their antennae which is absent on moths while a moth's antennae tends to be quite feathery compared to that of a butterfly.

The body of a butterfly is also usually quite slender, while that of a moth is often short and stout.

Both butterflies and moths have two pairs of wings that work as a single pair, so wings are not a good way to distinguish the two. However, there is a difference in the wings when they are at rest. A moth tends to hold its wings flat against the surface.

This could expose it to predators, but many moths are heavily camouflaged and blend in with their backgrounds. Moth wings are often disguised as lichens or tree bark, while some have prominent eye markings on their wings as a kind of disguise to ward of predators like birds.

Butterflies, with their brightly-coloured wings are much easier to spot in flight than they are at rest.

This is because resting butterflies, unlike moths, close their wings together and the underside of the wings is often dark and dull. The brightness of the wings may not necessarily be a disadvantage when they are in flight.

The brightly coloured wings of certain butterflies across the world can serve as a warning to predators that they are poisonous to eat.

Butterflies and moths are so similar that scientists classify them under one order called Lepidoptera. There are many more species of moths in the Lepidoptera order than there are butterflies. There are around 15,000 species of butterflies but moths account for well over 100,000 species across the world.

There are around 2,400 species of moth in Britain and only 58 species of butterfly. Because of their bright colouring and daytime flight most people can identify some of the different kinds of butterflies, but are less likely to be able to do so with moths.

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Published: 21/07/2003