British moths - identifying and observing

Moths tend to get overlooked or unnoticed by many of us, particularly when compared to butterflies, but I would argue that they are deserving of our attention for a whole host of reasons.

There have been more than 2,500 species of moth recorded in the British Isles, of these about 800 are referred to as ‘macro-moths’, they are the larger species which can usually be identified without resorting to a magnifying glass. Compare this to the sixty-one species of butterfly which are regularly recorded in the UK as either residents or migrants and it soon becomes apparent that there are a lot of moths out there!

British moths and butterflies: what’s the difference?

Probably the main reason why we notice butterflies more than moths is that they are diurnal, i.e. they fly by day, whereas moths tend to be nocturnal. Because of this behavioural difference it is interesting to note that most moths have ears whereas most butterflies do not, having evolved to rely on sight as their dominant sense.

Other differences between moths and butterflies include: a greater proportion of butterflies are colourful than is the case with moths, though some moths are very colourful (such as the pink and olive elephant hawk moth); butterflies usually rest with their wings closed together behind their backs (except when basking when they are usually flat out) whilst most moths rest with wings open (either flat out or in a ridge-tent shape); butterflies have long thin antennae, often with a club shape at the end, by contrast the antennae of moths are usually either feathery (in males) or spindly (in females).

However the rules which we use for differentiating between moths and butterflies are often broken. One species which breaks many rules is the six-spot burnet moth which is colourful, has club-shaped antennae and flies by day, but it is a moth!

In summary, to tell the difference between butterflies and moths look for these signs:

• The antennae – butterflies tend to have matchstick-shaped antennae (straight with a blob on top); moths usually have long tapering antennae, sometimes heavily feathered (especially in males for use in finding mates).
• Resting wings – butterflies tend to fold their wings upright on their backs like a book; most moths fold their wings flat like a jet fighter.
• Colour - butterflies are more likely to be colourful, but there a lot of colourful moths and plenty of drab coloured butterflies, such as speckled wood and meadow brown.

Moth species in the UK

We have some hugely impressive moths in the UK, the largest resident is the privet hawkmoth with a wing span of up to five inches and recently we have seen the return of another very large moth which previously went extinct in the UK in the 1960s, the Clifden nonpareil, or blue underwing.

This takes me to another significant point of interest with moths and that is their names. Some moth species have glorious names which just make me want to see them in the flesh. The death’s head hawkmoth has a skull shape on its back; the white ermine looks like the fur trim on robes; the eyed hawkmoth has large eye patterns and the privet hawkmoth larva eats the leaves of privet.

When naming moths there was clearly a dependence on the obscure little patterns on their wings leading to names such as the ‘figure of eight’ and the ‘figure of eighty’ moths and problems arose with so many species belonging to the same families so we have long names such as the ‘lesser broad-bordered yellow underwing’.

Some moths have different names for their different stages for example the larva of the garden tiger moth (Arctia caja) is so hairy that it has become known as the woolly bear. The garden tiger moth is one of our most striking species, it is found throughout mainland Britain, often in gardens, and was once regarded as common but recent figures suggest that its population in the UK has crashed by 92% since 1968.

The garden tiger moth, with its bright orange hind wing and stripes on the forewing, might have been an easy moth to name but others were not. We can sense the desperation or possibly sense of humour of the early naturalists when it came to naming the ‘uncertain moth’, ‘anomalous moth’, ‘conformist moth’, 'nonconformist moth’ and ‘confused moth’.

Moths can be seen throughout the year even in the winter, for instance we have the ‘December moth’ and the ‘November moth’ but they are most common through the summer.  

How to go moth watching

If you want to enjoy seeing more moths then it can be as simple as leaving an outside light on for the evening and seeing which species gather nearby. Alternatively shine a bright light onto a white sheet. If your passion continues then you might want to consider a live-moth light trap which can be purchased at many places online. These are boxes with a window and a light inside that atttracts moths into the box so they can be observed through the window before safely releasing.

Watching moths can be very rewarding. While you would be lucky to see 15 different butterflies in your garden, if you live in the south of England you could see 300-400 different moths.

Identifying moths

If you've got a moth you're struggling to identify you can use Butterfly Conservation's moth identification tool to filter moth varieties by size, colour and markings so you can view a selection that fits your criteria, and hopefully successfully identify the moth species you've seen.

Planting to attract moths

In the longer term if you have a garden it is beneficial to moths to have a wide range of nectar-bearing flowers throughout the spring and summer. It is helpful if these are night-scented. Some good ones to start with include: night-scented stock, jasmine, honeysuckle, red valerian and evening primrose.

Also when it comes to autumn, don’t be too tidy! A lot of moths and butterflies survive the winter by hiding in leaf litter and in amongst ivy on trees either as adults, pupae or eggs. So we should all leave some ‘untidy’ corners in our gardens and some areas of unkempt vegetation.

British moth numbers

If you're interested in observing and counting moths in your garden you can help contribute to a database of British moth numbers by taking part in Butterfly Conservation's annual Moth Night.

Some species are in sharp decline, with 60 species going extinct in the 20th Century. The v-moth has declined 99% in Britain, the white ermine has decreased by 70% and the blood-vein by 73%. While British native species are declining, new species from Europe are colonising Britain. They include tree-lichen beauty, established in 2000 and now found in Kent, Essex, London and Surrey. Clancy’s rustic has spread rapidly since it was first seen in Kent in 2002 and is thought to be breeding in southern coastal counties.

Moth Night takes place every summer, with participants around the country observing and recording the moths they see. For more details of Moth Night, visit mothnight.info, and for more on moth conservation see butterfly-conservation.org/moths.

Quick moth Q&A

Are moths nocturnal?

Many moths only fly at night (unless disturbed), but there are a lot of day-flying moth species, in fact there are more day-flying moth species in the UK than there are butterfly species. A lot of these day-flying moths might be mistaken for butterflies. Species include the humming-bird hawkmoths, broad-bodied bee hawkmoths, six-spot burnet and cinnabar moth.

Do all moths eat clothes?

No. Of the 2,500 species of UK moth, only two common species are responsible for eating clothes, and they attack only animal fibres such as wool, cashmere and fur. In the wild they eat owl pellets, fur from the lining of birds' nests and animal fleeces.

Find out how to get rid of clothes moths

How long do moths live?

Adult moths may only have a brief life, in fact many species do not even have mouths as they just need to be alive long enough to breed, with some only living a few short weeks. Many species will die after mating (males) or laying eggs (females). Most of a moth's life is spent as larvae and pupa, with many hibernating over winter.

What do moths do?

Moths play an important role in the ecosystem. They are hard-working pollinators often overlooked in favour of bees, and recent research has found they pollinate a lot more plant species than previously thought, including crop plants such as soybean, rapeseed and peas.

Moths also fulfill a role in the food chain. According to Butterfly Conservation, blue tit chicks in Britain consume 35 billion moth caterpillars a year. Adult moths are preyed on by birds and bats. A nursing mother bat can eat nearly 5,000 insects in one night.

What is the largest British moth?

The largest moth in the UK is the privet hawkmoth, with a wingspan of 90 to 120mm. This is still half the size of the world's largest moth, the atlas moth (240mm) found in Asia.

Why are moths attracted to light?

A lot of (but not all) moths are ‘positively phototactic’ – they’re drawn towards light. There is still a lot of debate about why this is, but it is likely to do with how they evolved to use the moon and stars for navigation before we had electricity and man-made fire. Our modern lamps confuse them.

What do moths eat?

Moth larvae eat different foods depending on the species. Some will only eat a small selection, while others will eat a broad range of plants, or in the case of clothes moths animal fibres. Adult moths do not eat much, but some will feed on nectar from flowers.

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