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To many people, moths are the drab, brown, poor relations of colourful, attention-grabbing butterflies. There is also a perception that moths only fly at night, while butterflies are out during the day and so much easier to see. Neither of these things is true, however. Some of our most bright and beautiful insects are actually moths and many are day-flying. They are also extremely important to the wider natural world. Moths are efficient pollinators as well as a food source to a large range of other organisms from bats to birds. Crucially, they also tell us lots about how the natural world is faring. If moths are in trouble, then you can be sure that lots of other species are too. So, it’s time to look again at this often-underappreciated group of insects and celebrate them as the magnificent moths they are.
What Are Moths?
Moths and butterflies are the only two members of the order Lepidoptera. This name translates as ‘scaly-winged’ and refers to the tiny wing scales that produce their patterned and coloured wings. Separation into two groups is largely a result of the human desire to classify everything. Nature, though, doesn’t always fit into neat, perfectly defined little boxes. So, biologically speaking, despite our differing attitudes to the two groups, there is very little difference between them. That being said, there are a couple of general rules of thumb applying to most moths and not butterflies or vice versa.
Most butterflies rest with their wings closed while the majority of moths settle with them flat. Another difference is that butterflies all have clubbed antennae with rounded tips while most moths have feathery ones. There are exceptions to these rules, however, such as the bordered white moth that closes its wings and burnet moths with their clubbed antennae. One difference that is definitely a myth is that butterflies are colourful while moths are brown and drab. Although there are some plainer, brown moths, many are extremely brightly coloured from the beautiful yellow of the brimstone moth to the contrasting reds, blacks, whites and yellows of the scarlet tiger moth.
Day-flying versus night-flying is also not a hard and fast difference between butterflies and moths. Interestingly, the latest research shows that butterflies evolved from moths by becoming exclusively day-flying approximately 100 million years ago. Researchers at first thought this was to avoid night-flying bats but now think the switch took place to take advantage of the diversification of flowering plants. But a surprising number of moths are also day-flying. The burnets, chimney sweeper, forester, cinnabar and migratory hummingbird hawkmoth are just some of the species to look out for in daytime. A few migratory butterflies, including red admirals and painted ladies, sometimes fly at night as well.
A Multitude of Moths
In a further attempt at categorisation, humans not only split moths from butterflies but also divide moths themselves into two groups. There are over 2,500 moth species in the UK alone (compared to just 59 butterflies) and subdividing them makes them a bit easier to deal with. This subdivision is based on size. Approximately 900 UK species are classed as macro, or larger, moths. These all have common, or English, names and are often fairly easy to identify with practice.
Micro, or smaller, moths often just go by a scientific name. Many are very small and hard to tell apart. Some are so small that their larvae feed within leaves rather than on them. Known as leaf-mining moths, they create visible tracks on the leaves as a result, with the track type pointing to the species involved. Confusingly, some micro moths are bigger than the smallest macro moths, and the subdivision is not a scientific one by any means.
Inevitably, because there are so many species, moths display a range of different lifestyles. As well as the split between day- and night-flying previously mentioned, a surprising number of both macro and micro moths are migratory, for example. Perhaps our most abundant visitor is the silver y moth, named for a silvery marking shaped like the letter. This species migrates from Europe each year in varying numbers. Sometimes thousands travel in huge fronts, as in 2016 when they were even attracted to the Euros Final in Paris whose lights created what was in effect a giant moth trap. Hummingbird hawkmoths are another migratory species. They usually appear from April onwards. Both species breed here, and our warming climate means that increasing numbers are likely to survive the winter.
Bee hawkmoths and clearwings, meanwhile, don’t even look like moths but mimic wasps and bees to protect themselves from potential predators. Other moth species, such as the mottled beauty, use camouflage to hide in plain sight.
The Importance of Moths
As well as being fascinating and beautiful in their own right, moths are extremely important within an ecosystem for a number of reasons. Many of us might not think of moths as pollinators but along with a host of other insects including bees and beetles, moths are essential when it comes to helping plants reproduce. And we now know that, incredibly, moths are actually more efficient pollinators than bees. Researchers found recently that moths are much faster when it comes to flower visits. This means they manage to achieve a lot of pollination in less time than many day-flying insects. Some moths also travel over relatively large distances which helps plants spread their genes further afield.
Moths are also a vital food source for an enormous range of other organisms. Many of our breeding birds feed their chicks moth caterpillars. These include blue and great tits, robins and pied flycatchers. The birds all time their breeding to coincide with peak caterpillar season in the spring. Cuckoos are even able to eat the large, hairy caterpillars toxic to many other birds. Shrews, frogs, toads and hedgehogs also eat caterpillars while bats eat night-flying adult moths. As part of complex food webs, moths are therefore crucial for helping us assess the environmental health of a region. If there are moths, we can be reasonably sure there will be a host of other organisms, all contributing to a balanced ecosystem.
Moths are also increasingly revealing the effects of climate change with new species arriving from abroad, more migrants surviving our milder winters, some species expanding their ranges north and caterpillars emerging earlier in the spring. They can even, in the case of the peppered moth, show evolution in action. Before the Clean Air Act of 1956, this species adapted its camouflage to soot-caked walls and trees in our cities as darker individuals were more likely to blend in and escape predation. They were then more likely to pass on their genes in a neat illustration of natural selection.
Our Disappearing Moths
Worryingly, our moths, along with many other insects, are in trouble. Over 60 species have become extinct in the UK since 1900. The 2021 Butterfly Conservation report into the state of our larger moths found that more species are declining than increasing. Over the last 50 years, the number of larger species recorded by the network of monitoring light traps fell by 33%. The south of England saw this figure rise to 39%. This is despite the fact that many species are expanding their ranges north as our climate warms. They may be found over a wider area, but they are much more thinly spread.
And of course these declines have a knock-on effect. With so many birds feeding their young caterpillars, fewer moths mean fewer birds. With moths making up such a large part of our bats’ diets too, they have also been hit. Reasons for the losses are likely to include climate change, habitat loss, the intensification of farming and light pollution.
Earlier caterpillar emergence due to advanced leaf appearance in the spring is having an impact on other species, as well. Resident birds, such as great tits, have begun laying eggs earlier as temperatures rise. At present, this is just about keeping pace with the earlier hatching caterpillars. Migrants such as the pied flycatcher, though, are finding it harder to adjust and are now at risk of arriving back on the breeding grounds too late to take advantage of peak caterpillar emergence. In addition, there is a fear that even our resident species will eventually be unable to keep up too. Moths are a perfect example of the complex relationships between multiple species in an ecosystem and the fact that no species exists in isolation.
Helping Moths
There are many ways to help our declining moths. With more and more people paving over garden spaces or installing plastic lawns, if you have a garden, keeping it naturally green is crucial. You can also make it pollinator-friendly, helping a huge range of invertebrates, including moths. This can include planting native flowers instead of overseas ones. Our moths have evolved to be able to feed from native plants and sometimes find it more difficult to access exotic ones. Planting a spread of flowers that bloom successively through the year also provides food for as many months as possible. Leaving messier, untidy areas is helpful as it provides places for moths and caterpillars to hide from predators, pupate and even hibernate. Events such as Plantlife’s No Mow May are also great to take part in. They promote natural, flower-rich areas for moths and other insects to feed in.
Moth trapping and recording your finds is another way to help moths. It has the added bonus of allowing you to see night-flying species you might otherwise not realise are visiting your garden. Whether it is a simple torch on a white sheet set-up or a purpose-bought trap, you may be surprised by just how many species you find. It lets us into a nocturnal world we don’t usually have access to.
My moth trap has caught some amazing species from the huge poplar hawkmoth to the daintier marbled beauty, neither of which I would have seen otherwise. It is also fascinating seeing particular species being replaced by others with different flight seasons as the year progresses, although late summer and its hoard of large yellow underwings can be a bit overwhelming! After trapping, I then record my finds via the National Moth Recording Scheme. This provides valuable data for researchers studying population trends.
Marvellous Moths
Moths are incredible insects. Not only are they the unsung heroes of plant pollination, but they are vital components of complex food webs. They are also beautiful and fascinating creatures that help us monitor the health of the environment. Far from being just plain, drab and boring, responsible for eating holes in our jumpers, there are over 2,500 species in the UK just waiting to be discovered.
Further Reading
With so many moth species in the UK, it can be hard to get to grips with identification at first. A helpful resource is the What’s Flying Tonight site. This shows you the species previously recorded in a given area during a particular season so you can start ruling out those from elsewhere and the wrong time of year.
If you are keen to get into moth trapping, wildlife supplies company NHBS has a great blog article with tips and information on trapping moths safely. They also have a range of traps for sale from their own cheaper model to more expensive set-ups.
To record your finds, register with the National Moth Recording Scheme here.
In Meetings with Moths, Katty Baird tracks down her own moths across a variety of Scottish habitats, meeting moth lovers and researchers along the way. From migration to reproduction, camouflage to how they sense the world, this book reveals some incredible insights into this often-overlooked group of insects. She also gives lots of advice for anyone wanting to start finding moths for themselves.
James Lowen’s photographic guide to moths is a wonderful starting point for anyone new to moth-spotting. Divided by season, it is easy to see what is most likely to be about at any given time. Similar species are then grouped together to help comparisons between species that look alike.
Lowen spent a year tracking down some of our most incredible moth species for Much Ado About Mothing. Along the way he explores just what it is about them that inspires such passion in some people and such fear in others. He also reveals the changing species he and his daughter find over a year in their own garden.