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 are seen as pure and wholesome creatures of the sun, while moths are the 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.