Small to very large insects, generally with two pairs
of membranous wings which, together with the body, are more or less clothed
with tiny scales, often brightly coloured. The females of some moths have
only vestigial wings and are flightless. Eyes fairly large, occupying most
of the head. The antennae are usually long, but vary greatly in form,
ranging from simple thread-like structures, sometimes with a terminal
club, to elaborate, feathery organs. Mouthparts in the form of a long
sucking tube (called the proboscis), which is coiled under the
head when not in use. There is a complex metamorphosis, with 3-9 larval
stages, depending on species, and a pupal stage, the latter often
enclosed in a cocoon. The larvae or caterpillars have three pairs of
thoracic (true) legs and several pairs of fleshy, abdominal prolegs.
They have biting and chewing mouthparts and most are plant-feeders.
All butterfly and moth caterpillars have a pair of silk glands opening
by way of spinneret on either side of the mouthparts. The silk is
produced as a fluid material, that quickly hardens in contact with air.
Caterpillars put their silk to several uses, including the formation
of protective tents and lifelines, but the major use is in the
formation of the cocoons which surround and protect the pupae of many
moths and a few butterflies. Adult Lepidoptera are perhaps the most
familiar and easily recognisable of all insects. They form a very large
order of more than 100,000 species worldwide, of which nearly 2,500
occur in the British Isles.
Butterflies and moths are of great economic importance
in the larval stages. Many species devour the foliage, shoots and roots
of trees and crops; a smaller number bore into stems and several species
damage timber; others attack manufactured goods such as carpets,
clothing and other fabrics, while a few are extremely destructive to
stored food products, including grain, flour, etc. One or two species
live in beehives, destroying and fouling the combs. On the other hand,
several moths are a direct benefit by yielding silk of commercial value
- the so called 'silk-worms'.
'What is the difference between a butterfly and a moth?'
- a straightforward question, but without a straightforward answer. The
division of the Order into butterflies and moths is really an artificial
split. In fact, there are no consistent features that distinguish all
the so called butterflies from all the so called moths. Nevertheless,
these names are firmly established, with the idea of butterflies as the
brightly coloured, day-flying insects which fold their wings together
vertically over the body when at rest, so that the undersides are
visible, compared with the popular notion of moths as generally rather
drab, night-flying insects which fold their wings flat or roof-wise
over the body when at rest, such that only the uppersides of the
forewings are visible.