Butterflies and Moths

28 October, 2007

Question: What’s the difference between a butterfly and a moth?

Answer: The answer to this question is not as simple as you might think. There are general features that can help us tell the difference between moths and butterflies, but there is no single feature that separates the two groups. 

Moths and butterflies fall into the insect order Lepidoptera. Lepidopterans can be distinguished from other insects by their scale-covered wings and their coiled proboscis (feeding tube).

Most moths have dull coloured wings, feathery antennae and fat abdomens. Most emerge from silken cocoons, rest with their wings out flat and fly around at night.

Emperor Gum Moth (Opodipthera Eucalypti)

An Emperor Gum Moth, Opodipthera Eucalypti
Photographer: Jon Augier, Source: Museum Victoria

Most butterflies are pretty colourful things that fly around during the day, emerge from chrysalises, hold their wings closed when resting, and have thin abdomens and smooth antennae that are either clubbed or hooked.

Wanderer Butterfly, Danaus plexippus

Wanderer Butterfly, Danaus plexippus
Photographer: Alan Henderson, Source: Museum Victoria

However, there are exceptions to all these rules.

Some moths are brightly coloured; some butterflies are drab. Not all moths spin cocoons and some are active during the day. There are butterflies that only come out when it gets dark and some weave silken structures.

The only rule you can rely on is that only moths have feathery antennae. But even this rule is problematic because the antennae of some moths are smooth and clubbed.

All we can really say is that if you find a lepidopteran with feathery antennae, it’s definitely a moth.

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juan lozano 15 February, 2011 17:20
As a kid we used to collect emperor gum caterpillars and keep them on a leaf covered branch of gum tree. We would then watch in awe as they spun a cocoon. I haven't seen a emperor gum moth or caterpillar around the bayside suburbs in 20 years. Where have they all gone. Juan Lozano
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