Starting to Identify Moths (part 2) - What family?

 

I don't know about you, but my natural instinct when trying to identify something - be it moth, butterfly or bird - is to look at pictures in field guides or online. But with many groups of insect, this doesn't work. Differences between species, or even families, can be subtle or even invisible to a casual observer, making them difficult to illustrate by drawings or photographs. The normal identification method for many insects - from beetles to caddis flies - is therefore to use a key. This will set out a series of choices, allowing you (in an ideal world) to eventually reach an identification. Many insect keys require the use of lenses or microscopes, and in some cases dissection of genitalia.

Happily, moths (generally) are an exception. The good news is that most macro-moths and many micro-moths can be identified from obvious visual characters.  As a result, most moth field guides do not contain detailed keys. Instead, they rely in the first instance on the user matching their specimen to an appropriate image before consulting the more detailed identification advice in their species accounts. 

The bad news is that a beginner trying to identify a moth is faced with a bewildering variety of images, many of which - at first sight - look very similar to each other!

If you haven't already seen it then you may want to take a look at the first blog post of this series, which gives more detail about the identification resources that are out there (link: Identification Resources Blog Post). There are a lot and that list is growing. The purpose of the present post is to suggest a way of making sense of all of those pictures! 

(Disclaimer: I'm only looking at macro-moths in the context of Britain and Ireland. Once you leave these shores, it gets even more interesting - and even more complicated!)

(Second disclaimer: This post is not intended to be comprehensive; the idea is to describe the families and sub-families that a beginner is most likely to come across.)

A Route Towards Identification

Obviously, you can trawl through the many hundreds of drawings or photographs one by one, which is time consuming and can be dispiriting. A better way to do it is to narrow your search - and the easiest first step along that route is to work out which family your moth belongs to.

You will search in vain for a simple key to macro-moth families. Mainly, this is because their formal definition is often based upon obscure characters: these include genitalia, the pattern on veins on their wings and features such as ocelli (additional lenses sited near to the main compound eye) and tympanal organs (which sense pressure or vibration). In addition, some characters only relate to caterpillars (larvae), which is hardly helpful when you're looking at an adult.

The other complication is that families have a nasty habit of changing as more information becomes available to the taxonomists. Hopefully, things have now settled down, although I wouldn't bet on it.

[As an aside, if you are looking for a book about general moth biology and evolution I can recommend David Lees and Alberto Zilli's Moths: Their biology, diversity and evolution which is published by the Natural History Museum. Reasonably priced, and nicely illustrated, it includes images of moths from the British Isles and around the world (NHBS bookshop link here)]

Macro-moths and Micro-moths

The distinction between 'macros' and 'micros' is so well established that it comes as a bit of a shock to learn that it has almost no scientific basis whatsoever.  Apologies for a short detour into the world of taxonomy - the classification of life.

You can picture the evolution of moths and butterflies (which together make up the Order Lepidoptera) as a series of branches, as new forms have split off and diversified over millions of years. The older the split, the less that the modern day representatives of these branches are related to each other.

There are currently around 74 families of Lepidoptera (including the butterflies) on the British checklist (compiled by Agassiz, Heckford and Beaven in 2013, and regularly updated - link to the Natural History Museum data portal) . The checklist gives a two-part number to each species, the first part signifying its family, the second part being unique to that species. So the Vestal moth pictured at the start of this blog post has been given the number 70.038, meaning that it is the 38th species on the checklist in the Geometrid family (Geometridae) - family number 70. 

In simple terms, the families that are classed as micro-moths were the earliest to split off from the 'main' evolutionary line of moths and butterflies (around 100-200 million years ago). You could call them 'primitive', although their surviving members are actually as modern as any other living moth. Most of the macro-moths appeared on the scene later (around 80-100 million years ago). 

This evolutionary sequence is reflected in the checklist classification. Micro-moths, which comprise most of the moth families (around 50 out of 74), generally have the lower numbers, while macro-moths are generally higher.

However, to complicate things, a few of the more 'primitive' families are generally included with the macro-moths. The only reason for this is that they are large and easily observed. But they are only distantly related to the main group of macro-moths.

To bring this together, here is a list of the macro-moth families of Great Britain and Ireland, with their checklist number, scientific name, common name and the (approximate) number of resident species in our area - taken from the 3rd edition of Waring and Townsend (see my resources blog post for the detailed reference). This may look off-putting, but things are actually less complicated than they may first appear.

• 3. Hepialidae - Swift Moths (5 species)
• 50. Cossidae - Leopard and Goat Moths (3) 
• 51. Sesiidae - Clearwings (14)
• 53. Limacodidae - Festoon and Triangle (2)
• 54. Zygaenidae - Forester and Burnet Moths (10)
• 65. Drepanidae - Hook-tips and Lutestrings (6)
• 66. Lasiocampidae - Eggar and Lappet Moths (10)
• 67. Endromidae - Kentish Glory (1) - but don't look for it in Kent!
• 68. Saturnidae - Emperor Moth (1)
• 69. Sphingidae - Hawk-moths (9 plus immigrants) - everyone's favourites
• 70. Geometridae - Geometrids (around 300)
• 71. Notodontidae - Prominents, Kittens and Processionaries (21)
• 72. Erebidae - Tussocks, Tigers, Footmen and the like (89 species) - a mixed bag
• 73. Noctuidae - Noctuids (around 370)
• 74. Nolidae - (14) - another mixed bag that can easily get confused with some micros

Several things jump out of this list.

First, and most importantly, the vast majority of macro-moths are in two large families - the Geometrids and Noctuids. Getting a feel for these two is an important step in learning to identify moths. It's a pity that these families don't have better common names. Geometrids (or geometer moths) are named for their caterpillars, some of which loop along as if they are making a measurement ("inchworms"). Elsewhere in the world, Noctuids are known as owlet moths, armyworms or cutworms, but none of these names are used here.

Second, the Hepialidae (Swift Moths) are real outliers in an evolutionary sense - family number 3 on the checklist. Their closest living relations are tiny micro-moths, not that you would know it from looking at them - for example this female Ghost Moth (below).

Ghost Moth (female) - an 'honorary' macro-moth (one of the Swift moths)

Third, you will see that there is a 'gap' between the Zygaenidae (54) and Drepanidae (65). This contains two important micro-moth families - the Pyralidae (61) and Crambidae (62) - which both include a few species that are large, common and conspicuous enough to be confused with macro-moths. Mother of Pearl is a good (and common) example - see below. The butterflies are also found in this 'gap' - they are families 56 to 61 in the Checklist. I've done a separate blog post on the differences (or not) between moths and butterflies - link here.

Mother of Pearl - a big "micro" moth (family: Crambidae)

Going Forward - First, check out the Big Two

So, you have found a macro-moth. How can you can assign it to a family?

The first job is to check whether it is a member of either of the 'Big Two' families, the Geometrids or the Noctuids. Given that these account for over two-thirds of our macro-moth species, including most of our commonest moths, there's a good chance that it will be. 

(In Dorset, we publish an annual report that includes the Top Twenty most recorded moths for the year - downloadable free via this link. In 2022, all but three of these were in the 'Big Two' families.)

This post briefly runs through the moth families that you are most likely to encounter, giving typical examples from each one - starting with the 'Big Two'. The idea is that you should start to get a 'feel' for the characteristics of each family, which should help to narrow down your search for the correct species.

First, some typical Geometrids:

Typical Geometrid - Common White Wave

Grey Pug - another Geometrid (but pugs can be tricky!)

Mocha - a rarer, but lovely, Geometrid

Brimstone - an attractive and common Geometrid

Flame Carpet - the carpets are an important Geometrid group

Large Emerald - a stunning Geometrid

Early Thorn - a Geometrid that holds its wings vertically

While there's plenty of variety, it's also possible to observe a general theme. In Geometrids the wings rarely overlap and are usually held out flat like a basking butterfly. One group (the thorns) rest with their wings held vertically (or near-vertically); some other geometrids, like the carpets, will also sometimes close their wings above them. (This is annoying when you want to identify them.) 

Turning to the other 'Big Two' family, here are some typical Noctuids. Most will lie flat with wings partly or wholly overlapped (a good pointer) but a few adopt a more upright (tent-like) position, like the Silver Y pictured a bit further down.

Typical Noctuid - Clouded Drab (a common Spring moth)

Large Yellow Underwing - one of the commonest Noctuids

Flame Shoulder - another common Noctuid.

Hebrew Character - a common Spring Noctuid

Coronet (Noctuid) - can be a common where you find Ash trees.

Silver Y - a Noctuid with an upright (tent-like) stance. A common migrant species.

Again, there is a clear general theme - Noctuids are usually stocky or chunky moths, with wings either overlapping or lying side-by-side (but not spread out like a butterfly). Most wings sit fairly flat, but some rest in a tent-like pose. But do note that some other families contain moths with these characteristics, for example the Ermines, which are found in our next family ...

Not the Big Two? Check the next biggest family.

So, what about the other families? I'll deal with the next largest first (the Erebidae) and then move onto some of the smaller - and perhaps more distinctive - families.

For me, the Erebidae doesn't hang together as a family. Its members appear very diverse, with no obvious linking visual theme. And indeed the taxonomists have found them to be problematic; anyone with a first edition of Waring and Townsend (2003) will discover that this family didn't even exist then!

Luckily, however, they break down into a few distinctive groups. Here are some typical ones: examples of the Snouts, Ermines, Tigers, Footmen and Underwings (excluding Yellow Underwings!), which all live within this family.

Snout - common and frequently seen (Erebidae).

Buff Ermine - a common member of the Erebidae. Like many Ermines, this is easily confused with the Noctuids. 

Garden Tiger - my favourite of the Tigers (Erebidae) but sadly declining. Tigers are usually bright and colourful.

 

Dingy Footman - Footmen are a tricky group of the Erebidae

Red Underwing - sensational moths, but they don't like to hang around (Erebidae)

As I said, there is no obvious visual linking theme to this family, but each group (or sub-family) within the moths are generally distinctive.

Prominents - The Next Biggest Family

There may be only 21 species in the family, but some members of the Prominent & Kitten family (Notodontidae) will certainly turn up in your moth trap. Usually resting in a tent-like position like some of the Noctuids, they tend to appear more furry, and even more chunky, than most members of that family. Here are three typical examples:

Buff Tip - a crowd-pleasing twig-mimic (Notodontidae).

Pebble Prominent (Notodontidae).

Sallow Kitten (Notodontidae) - easily confused with Poplar Kitten.

Best of the Rest - Other Distinctive Families

Ignoring four families that are unlikely to turn up in your trap (but congratulations if they do!) - namely the Clearwings, Festoon/Triangle, Kentish Glory and Emperor Moth - that leaves us with seven more families that you are very likely to come across. Happily, most are pretty distinctive. Of these, three families can be easily identified: the Hawk-moths, the Eggars and the Burnet Moths. I'll start with these.

The Hawk-moths (family Sphingidae) are large and obvious. Even better, some are common. Here's two for starters:

Elephant Hawk-moth

Privet Hawk-moth - one of the biggest moths in Britain and Ireland

The Eggar moths (family Lasiocampidae) contain some of my favourite macro-moths. Like some other moths (for example most of the Notodontidae) the adults cannot feed. Most are large and particularly furry: here are two typical examples:

Oak Eggar (female)

Drinker - another Eggar moth

Although unlikely to appear in a light trap, the Burnet Moths (family Zygaenidae) are frequent and visible day-flyers in grassland and other open areas - especially sand dunes and flowery chalk grassland.  Look for them on flower-heads. This is the most widely spread species in Britain and Ireland:

Six-spot Burnet Moth

Four more families to go! I've already introduced the Swift Moths (family Hepialidae) with the image of a Ghost Moth earlier on in this blog post. These hold their wings in a tent-like position like some of the Noctuids, but have a fairly consistent, rounded wing shape. Very often the abdomen pokes out beyond the back of the forewings. Here's another characteristic Swift Moth species that may well turn up in your light trap:

Orange Swift - a common Swift Moth

Only three species from the Goat and Leopard Moths (family Cossidae) are found in Britain and Ireland. All have long wings, which are also held in a tent-like resting position. Leopard Moth is most likely to appear in a moth trap, although it is absent from Ireland, Scotland and parts of Wales and Northern England. A lovely moth with distinctive black spots on a white background.

 

Leopard Moth (Cossidae)

The Hook-tip and Lutestring family (Drepanidae) is another family that has caused problems for the taxonomists. It is divided into two groups (strictly, sub-families) that look quite different from each other. However, within itself, each group has a fairly distinctive character.

The first group (the Hook-tips) generally hold their wings out flat like the Geometrids. The clue to their identification is in the name - look out for the hooked tip to their forewings (although, as we'll see later, not all hook-tipped moths are in this family!). Pebble Hook-tip (below) is a common and typical example of the Hook-tips. 

Pebble Hook-tip (Drepanidae)

Having said that, there is one complete outlier in the Hook-tip sub-family - the Chinese Character. It is a common and fascinating little moth that mimics bird poo with great accuracy. It can be easy to miss.

Chinese Character - an unusual Hook-tip (Drepanidae)

The other sub-family of the Drepanidae are the Lutestrings. These look very like Noctuids, and I can't think of an easy way to separate them from that big family. However, there aren't very many of them and they are easily learned. First, a distinctive one; and then one that's a bit more confusing.

Peach Blossom - a distinctive member of the Drepanidae.

Common Lutestring - one of the Drepanidae that's easily confused with the Noctuids

And that leaves us with the Nolidae. Sitting after the Noctuids at the back of most field guides, these can get a bit overlooked. Like the Drepanidae, there is no obvious linking visual characteristic for the family as a whole, but also like that family, they are few in number and easily learned. Six of the family (all various kinds of Black Arches) do share a consistent 'look'. They are small, so there is a danger of confusing them with some micro-moths. Of these, Least Black Arches is the most widespread across Britain and Ireland, but it's still not common.

Least Black Arches (Nolidae) - not a micro-moth!

Very different, and rather more common (I'm happy to say) is the beautiful Green Silver-lines.

Green Silver-lines (Nolidae)

 Whew! Well done if you've made it this far.

Finally ... what's in a name?

There's been a lot to get through in this blog post, but I'll leave with a quick word of warning about common (or vernacular) moth names. The message in a nutshell is as follows: common moth names can be inconsistent and confusing! Many relate to visual features that can be found across more than one moth family. Do not assume that a similar common name implies any sort of actual relationship. 

For example:

• Black Arches (family Erebidae) is not related to Least Black Arches, Kent Black Arches and the others in the Nolidae family.

Black Arches (Erebidae) - no relation to the Nolidae.

• And the 'Arches' name applies to moths in other families as well - such as Green Arches (in the Noctuid family).

Green Arches - a Noctuid.

• Beautiful Hook-tip (also family Erebidae - which has a lot to answer for!) is not a member of the Hook-tip family (Drepanidae), although it really looks like one.

Beautiful Hook-tip (Erebidae) - not in the Hook-tip family (Drepanidae)

• There's a lot more of this, but I'll leave it there. There's more identification advice to come, so watch this space ...

Into the Mountains (part 2): a scarce mountain moth

 

Black Mountain Moth - Beinn a'Chlaidheimh 22.6.24

(Post updated 10 July 2024)

As mentioned in the last blog post (link here), I like to get out into the mountains. Seeing the wildlife of the uplands is an added bonus. In Scotland, that means frequent sightings of Red Deer, Ptarmigan and Mountain Hares, as well as rarer glimpses of Dotterel and Snow Buntings. I have also been lucky to have a couple of encounters with a moth that rarely descends from the higher peaks. To see one, you need to get your boots on.

I'll start by correcting a possible misunderstanding. You will not find a Black Mountain Moth Glacies coracina (previously Psodos coracina) in the Black Mountains of the Welsh-English borderlands. It is, instead, a black moth that lives on mountains. In fact, its distribution is very limited - within the UK, Black Mountain Moths are restricted to the Scottish Highlands (see NBN distribution map here), usually over 600 metres in altitude. The distribution map shows clusters in two main areas of the Highlands - the Cairngorms (in the east) and the hills around Loch Cluanie and Loch Shiel (in the west). However, I have walked both of these areas on many occasions without seeing one. Both of my Black Mountain Moth encounters were further north, in the Fisherfield wilderness to the south east of Ullapool. I found my first one on the rocky shoulder in the foreground of the picture below; this is Mullach Coire Mhic Fhearchair, which Munro baggers will know as one of the 'Fisherfield Five'. It is awkward to get to: our expedition involved an overnight camp in the glen below. The mountains in the background are the more familiar Torridon peaks, with Slioch the most prominent. 

View north from Mullach Coire Mhic Fhearchair - Black Mountain Moth habitat

The second encounter, last month (June 2024), was on another Fisherfield mountain (Beinn a'Chlaidheimh), when my hillwalking colleague Richard spotted the individual pictured at the start of this blog as we were descedning from the summit. It is highly likely that the relative absence of Black Mountain Moth records in the Fisherfield area is a result of the relative absence of moth recorders on these remote mountains! Needless to say, I have submitted both of my records to the relevant County Moth Recorder, so hopefully a couple more dots will be added to the map in due course.

The first moth that I found (below), one of two that I saw on that walk, was flying low above the ground. This must be a behavioural adaptation to the windy conditions of their preferred habitat. The females tend to stay on the ground, although they are not wingless like some other species. I have only seen males; their flight action makes them more conspicuous. Not a lot else is moving around at that altitude.

My first Black Mountain Moth - Mullach Choir Mhic Fhearchair 19.6.21

Black Mountain Moths have a number of other adaptations to life in the uplands. Their black colouration comes from the pigment melanin which helps to absorb heat more efficiently as well as protect from UV radiation - 'thermal melanism' (Majerus, 2002; Lees & Zilli, 2019). Their furry bodies provide extra insulation. The black colour is also likely to provide some camouflage for these day fliers when seen against the generally dark backgrounds of the peaty and rocky mountain habitats.

A further possible adaptation is discussed in E.B.Ford's classic New Naturalist Moths (Ford, 1955), which states that Black Mountain Moths are more common in odd years of the calendar, with the Northern Dart - an upland moth that I have yet to track down - being more easily found in the even years. He comments that while it is understandable that a high mountain moth might take longer to develop and emerge, the establishment of a two year cycle remains 'mysterious'. Waring & Townsend (2017) say that the two year cycle is 'almost certain' because 'on some sites the adults appear to be more numerous every other year, generally in odd-numbered years'. However, a quick literature search has found no recent work that sheds light on this matter. Indeed, one rather obscure paper (Kaaber, 1996) states that Black Mountain Moth shows no alternate year rhythm in northern Scandinavia. So I wonder how robust this observation really is: for what its worth, my own small sample of records were in both odd and even years. It would be interesting to examine the data in more detail.

Beinn a'Chlaidheimh North Ridge - site of the June 2024 Black Mountain Moth encounter

The global distribution of  Black Mountain Moth emphasises its preference for upland habitats (link to GBIF distribution map here): it is found primarily in Scandinavia, the Alps and the Pyrenees, so its UK population is a bit of an outlier. There is some evidence that, like birds such as the Ptarmigan, it is found at lower altitudes at higher latitudes.

The restricted distribution of Black Mountain Moths - particularly in Scotland - suggests that the species may become a conservation concern in the light of a warming climate. If so, this hasn't been recognised by its inclusion as a UK Biodiversity Action Plan species - although that list is now looking rather dated. (The rarer Netted Mountain Moth is identified as a BAP priority species.) But, short of general climate change policies, its difficult to know what specific actions could be undertaken in respect of the Black Mountain Moth. Its habitats are generally well away from the pressures of development or intensive agriculture. Passing hillwakers generate limited disturbance. The main larval foodplant (Crowberry Empetrum nigrum) has a wider range within the Scottish Highlands than the moth, implying that foodplant availability is not the limiting factor for the moth's distribution.

At the moment, no population trends are available for Black Mountain Moth; the excellent Atlas of Britain and Ireland's Larger Moths notes that there has been a dramatic increase in records over the ten years to 2019, partly as a result of hillwalkers with mobile phones. This suggests greater recording effort rather than an expanding population, but at least numbers of the moth appear to be presently secure. Nevertheless, this species is one to watch carefully in the future.

Acknowledgements

Thanks to Richard Leslie for locating the second Black Mountain Moth on Beinn a'Chlaidheimh and to Phil Sterling for a useful discussion about the species.

References

Ford, E.B. (1955) Moths. London: Collins New Naturalist.

Lees, D.C. & Zilli, A. (2019) Moths. London: Natural History Museum.

Kaaber, S. (1996) 'Notes on Xestia alpicola ssp. atlantica nov.( Lep., Noctuidae) on the Faroe Islands.' Fróðskaparrit-Faroese Scientific Journal, pp.107-113.

Majerus, M. (2002) Moths. London: Collins New Naturalist.

Randle, Z., Evans-Hill, L. et al. (2019) Atlas of Britain and Ireland's Larger Moths. Newbury: Pisces Publications

Waring, P., Townsend, M & Lewington R. (2017) Field Guide to the Moths of Britain and Ireland (3rd ed.) London: Bloomsbury.

 

On Moths and Butterflies

 

My slightly tongue-in-cheek social media post yesterday (below) provoked an entertaining exchange of views on the differences - or, more exactly, the lack of differences - between moths and butterflies. 

I chose the images deliberately to suggest the similarities between moths and butterflies. But for many people there is a deep and profound divide. "I love butterflies" versus "I hate moths". Butterflies flap colourfully around in the sun, while moths are seen as sinister creatures of the night that eat your carpets. 

This bias appears surprisingly pervasive. Butterfly Conservation does a lot of great work for moths. (I am a member, and I urge you to join too - there's a link here.) It runs the National Moth Recording Scheme, carries out moth research (check out the excellent State of Britain's Larger Moths 2021 report, which can be downloaded free from the website) and undertakes moth conservation projects. Its Atlas of Britain's and Ireland's Larger Moths is an essential resource (I sponsored a moth in it - see whether you can find it!). Through its #MothsMatter campaign, Butterfly Conservation acts as a much needed cheerleader for moths, while its officers appear regularly on the TV to explain why most moths do not actually eat carpets.

However, you only have to look at Butterfly Conservation's members' magazine to understand that moths are secondary to the interest in butterflies. The magazine is called "Butterfly", for a start. In a (very) much smaller font you will find the strapline: "Saving butterflies, moths and our environment". Butterfly Conservation's Twitter (X) handle is @savebutterflies. Several times, I have suggested to BC officers that the charity's name could be changed to include a reference to moths: the response has always been on the lines of "it's just not going to happen". 

Aside from the fact that a lot of BC members simply like butterflies (and there's nothing wrong with that), there is another (largely unstated) reason why moths aren't given equal billing. Namely, the fear that mentioning moths will put people off from joining and donating. I don't know whether this is based upon any hard evidence - it may have been focus-grouped, I suppose - but there's no denying that there is a weird, and largely irrational, dislike of moths out there. A particularly bonkers example is in a Guardian comment piece from 2012, titled "Why I Hate Moths". 

(By the way, if you do open this link, you will see that the main photo, which has appeared all over the place including the Times, Daily Express and Good Housekeeping, is a classic piece of deliberate misinformation: two geometrid moths have been placed next to a hole in a woollen jumper. As most of you will know: (1) these aren't clothes moths, (2) only a tiny number of moth species damage fabric and (3) it's the larvae that do the damage, not the adult moths.)

But if the level of aggression against moths in some quarters seems disproportionate, then it's perhaps also rather odd to focus too strongly on butterflies in preference to moths. Three reasons why:

First - many moths are spectacular and conspicuous. There are at least as many day-flying moth species in Britain and Ireland as there are butterflies. Below are a couple of the more showy ones - Jersey Tiger, a species that has colonised the south of England and is heading north, and Narrow-bordered Five-spot Burnet - one of a number of burnet moths, all of which are vibrantly coloured.

Jersey Tiger - Dorset

Narrow-bordered Five-spot Burnet - Northumberland

Second - butterflies only make up a small part of the Lepidoptera (the order containing moths and butterflies). Published numbers vary, partly because new species are being added to the list regularly, but a good estimate of the total count for the Lepidoptera is around 157,000 species (Stork, 2018), of which between 15-20,000 are butterflies - around 10%. In Britain and Ireland, the difference is even more stark: we have around 60 resident butterfly species compared to around 2,500 moths - only about 2.5%. 

Butterflies are the exception; moths are the rule.

This means that, even in our biologically impoverished islands, moths demonstrate significant and interesting species diversity. There is much to learn, and fascinating stories to tell. For example, studies of moths have pointed towards reasons for the general decline of insect numbers (see my blog post on this here). 

Third - and this is the crucial one - there is really no meaningful distinction between moths and butterflies anyway. As we have seen, moths fly during the day as well as at night. Many moths are bright and colourful. The uraniid moth from Ecuador's Yasuni National Park pictured below is perhaps an extreme example, but it makes the point. See also the Cream-spot Tiger photo at the head of this blog post.

Uraniid moth (Urania leilus) - Ecuador

Look harder at the taxonomy and you will struggle to find differences as well. Butterflies are grouped together in a 'superfamily' (the Papilionoidea), that appears to have split-off from the main 'family tree' of the Lepidoptera around 100 million years ago. A recent study has suggested that this split took place in North America (Kawahara et al., 2023). But the butterfly superfamily sits within the rest of the Lepidoptera - and these are all moths. They include families that are more 'primitive' than butterflies (for example that have a single genital opening for mating and egg-laying) as well as families that share the same characteristics as butterflies - for example two genital openings (Lees & Zilli, 2019).  The oft-quoted 'fact' that butterflies have clubbed antennae while those of moths is tapered is confused by the sheer diversity of moth forms. For example, the antennae of Burnet Moths, such as this Six-spot Burnet below, end in a wider section that then tapers. Not unlike that of a Dingy Skipper (also pictured below).

Six-spot Burnet - Dorset

 

Dingy Skipper - Dorset

As such, there is no one characteristic that separates butterflies from moths. Moths can therefore be defined as 'Lepidoptera that aren't butterflies'. But - to cut to the chase - it's far easier to say that butterflies are actually moths!

So, let's hear it for a bit of blurring of boundaries, and leaping out of traditional silos. If you love butterflies, then try dipping a toe into the magical world of moths. You won't regret it!

References

Lees, D.C. and Zilli, A. (2019) Moths: Their biology, diversity and evolution. London: Natural History Museum

Kawahara, A.Y., Storer, C., Carvalho, A.P.S., Plotkin, D.M., Condamine, F.L., Braga, M.P., Ellis, E.A., St Laurent, R.A., Li, X., Barve, V. and Cai, L. (2023). 'A global phylogeny of butterflies reveals their evolutionary history, ancestral hosts and biogeographic origins.' Nature Ecology & Evolution, 7(6), pp.903-913.

Stork, N.E. (2018) 'How many species of insects and other terrestrial arthropods are there on Earth?' Annual Review of Entomology, 63, pp.31-45.