To moth or not to moth? That is the question

I had a discussion recently with a former moth-er who disposed of her trap after having an ethical pang of conscience about all the moths she had been disturbing over the years. She suggested that there are hundreds of thousands of people trapping all over the country and that we’re interfering with reproduction cycles by doing so. I felt her opinion was at best misguided.

My immediate thought was that that number was way off. I know two other people in this village of 4000 or so who trap regularly, as do I, but this is quite a sciencey village, close to Cambridge, so could be exceptional. There’d have to be 3-4 people in every of the 44000 villages and towns across the UK for there to be hundreds of thousands of people trapping. This from a straw poll I conducted among moth-ers online is very unlikely. If anything there are a few hundred across the British Isles mothing regularly, maybe at most 1000. Even if we assumed 1 per 1000 households, there are just 28 million households, that would still only be 28000, but I reckon the hobby is done by far fewer people.

Either way, is “catch-then-release” moth trapping detrimental to moths or does the scientific knowledge that might be gleaned and the raised environmental awareness among those who moth outweigh any negative effects? Perhaps we could consider the impact of mothing in the context of the hundreds of moths consumed by a single bat eat each night. My trap usually has a few dozen moths by morning. I’ve seen three Pipistrelle bats circling our garden together at dusk, over the years, long before I was mothing. Through the night they will be hoovering up a lot more than any single trap catches.

I think the real problem isn’t those interested in the insects. It’s widescale habitat destruction, intensive farming, and climate change, these are having a much bigger detrimental effect on moths. Moreover, moth trapping is about respect for nature, moth awareness and understanding, and record keeping add to our knowledge about the rarities, their behaviour, their behaviour, migration, and range extension trends. If moth-ers submit records and share information, and discuss their mothing, which a lot of them do, that can only be a good thing for lepidoptery. It might even guide those who try to look after the environment, and perhaps even nudge development away from sensitive areas.

I asked members of the UK Moths Flying Tonight Facebook Group for their thoughts on this subject and reproduce a few of their comments, edited for brevity here:

Martin H: I trap once or twice a month on my local patch. However, I’m involved in a project to monitor the moths of the Balearic Islands and will trap every night in the same place for anything between one and six weeks. There is absolutely no evidence that this has any adverse effects on numbers or species diversity and the project itself has been going for more than 25 years. There’s also no evidence of recapture of the same individuals. Local habitat change has had an effect. This is all based on my experience as a professional lepidopterist for 40 years.

Gary G: I’m not a moth trapper, I joined to learn more about moths. From my experience collecting ladybirds using sweep nets and beating trays I often find they mate in my specimen tubes before I release them. I wonder if this happens in moth traps?

Alan S: Yes it does. Sounds like [mating in moths traps] might be a beneficial side effect then. Add to that the huge benefits gained for ecology from recording the moth distribution and population trends and I’d say you’re on to a winner.

Jerry S: Also, more male species seem to be attracted to light.

Alan S: In the grand scheme of things it doesn’t make much difference unless people are constantly trapping the honeypot sites for scarce species and even then as long as it’s catch and release it should be OK. We survey lots of sites and these don’t get done as regularly as we’d like. The sites are huge and we only cover a tiny fraction each time we survey so impact is negligible.

Shaun P: If trappers are doing the right thing and sending in records, it should be easy to find out the number. I’m in Cornwall and I suspect the number of regulars is quite low judging by records and talking to others.

Sean O: Cars are a bigger problem…a drive in the countryside at night, moths continually in the headlights with several hitting, then multiply that by the number of cars on the roads around the country…that’s a lot of moths in a year!

Giles K-S: My experience (in rural Herefordshire) is that I actually see very few moths in the headlights – so few that you can almost count them individually. I think it’s just a symptom of the wider decline in insect numbers.

Mark G: I hardly see any. I remember the moth snowstorms of old in the 1960s.

Sciencebase: Yes, been discussing this for a while, 15-20 years ago, driving anywhere meant cleaning the windscreen regularly, not so these days.

Giles K-S: Moth traps only attract moths passing within a very short distance of the trap – in the range of 3 to 10 metres. Of much greater concern is the large number of other artificial light sources disrupting the activity of moths, bats and other nocturnal species.

Mark S: There are certainly [fewer] than 150 trappers in VC55 Leics & Rutland, and I’m sure there are many VCs with many fewer. Responsible catch & release, and recording does far more good than damage.

Leonard C: Static traps run all the time all around the country and provide valuable data. The only way we can help decline is to actually record numbers and then act upon such data by increasing habitat and foodplants.

Summer de G: [Moth-trapping] probably has no more impact than leaving outside lights on all night or garden lights.

Ben S: Moths are at more danger from birds, the bat roost at the bottom of my garden, artificial lights at night, and our clearing land, driving our cars etc.

Derek C: [Simply] mowing the lawn probably [kills] quite a few!

Kiera C: I think moth people are likely to be far less of a problem than the broadcast application of pesticides by industrial agriculture, the destruction of habitat, and the effects of climate change. If trapping and freeing moths just gets people to think about those bigger issues, to join environmental groups, to change their patterns of consumption, and to see the beauty in nature so that they want to look after it and protect it, then that possibly outweighs harms.

Lee T-W: I find that numbers in my garden increase slightly year on year (for common species). I wonder if attracting them brings them together to create greater breeding opportunities, also trappers are likely to manage their mini-habitat more beneficially?

Pete M: As long as people are sensible with holding off if you’re attracting predators, do all you can to prevent casualties, don’t trap every single night, and always send records in so your data has some use, I can’t see any real ethical issues.

Privet Hawk-moth, Sphinx ligustri

It’s always a delight to spot a big lep in the scientific trap when you approach it each morning. This morning’s treat was a Privet Hawk-moth (Sphinx ligustri), but once I’d lifted the lid I realised there were two. This is a big moth (55 mm from the nose to wing-tip, with startling pink and black markings on its body and hindwings, which are revealed when it opens its wings.

This is the largest resident moth species in the British Isles. It flies June to July in a single breeding season. I had previously seen and phone-photographed a pair roosting on a concrete bollard in the village (14 Jun 2019, 21h20, Wilkin Walk, Cottenham, to be precise). But, not seen any since.

Two Privet Hawk-moths, drawn to actinic light trap
Two Privet Hawk-moths, drawn to an actinic light trap
Side view of the Privet Hawk-moth

In repose, the Privet Hawk-moth is, like many other species, well camouflaged against natural backgrounds, such as leaves and bark. Its startling colours when it opens its wings are presumably an anti-predator adaptation like those of many other species, but not latching on to the “eyes or face” type of the Eyed Hawk-moth or the Emperor Moth. Black and pink stripes are more likely to be perceived as venomous or otherwise poisoning, bad-tasting, or stinging.

Face-on view of the Privet Hawk-moth

Industrial evolution and the Peppered Moth

A Peppered Moth, Biston betularia, was drawn to my scientific moth trap last night. This species is probably the most important moth, scientifically speaking. It’s something of a Victorian scientific hero, in fact, and a speckly example of how evolution doesn’t always need millions of years to happen, but can take place within a decade or so if not faster.

During the sooty days of the Mancunian branch of Britain’s Industrial Revolution, this creamy white moth with black peppery speckles evolved to an almost black form (Biston betularia betularia morpha carbonaria). Originally, the light form had been well camouflaged on lichen, which meant it was hard for birds to see and so safe from becoming avian lunch. But a lot of the lichen was killed off by the smoke and smog of the industrial revolution and coated with soot. Those mainly white Peppered Moths were no longer well camouflaged and were easy pickings for birds.

However, a mutation arose in this species that for all intents and purposes gave rise to a melanic, dark, form of the moth. No more bright white but a sooty black moth that was now camouflaged on the dark surfaces of the industrial era. Now, the dark moths that evaded detection by birds could live to breed and pass on their genes for this melanism. It seems that the mutation arose around 1819 as the carbonaria form was not noted by naturalists before this date.

The rapid change from a bright to a dark, melanic form, industrial melanism as it is now known, provided evidence of survival of the fittest, natural selection, and evolution in action. By the end of the century, 95 per cent of the Peppered Moths in Great Britain were carbonaria.

The melanic form began to decline in Britain after the Clean Air Act of 1956 when smokeless fuels came to the fore and uncapped pollution was no longer acceptable. I am yet to see the melanic form, hence the lack of photos, but it certainly still exists in the wild. This reversal of the adaptation lends additional support to the evidence for the original industrial evolution.

Peppered Moth
The Peppered Moth is a classic example of industrial evolution

There was some concern in the 1990s that the original research proved nothing as it didn’t take into account the moth’s natural resting places and that moth migration might skew the actual results and may have led to some of the effect. However, interesting research by the late Michael Majerus discussed and followed-up here in the journal Biology Letters provides strong evidence that reinvigorates the original hypothesis of industrial melanism in the context of predation by birds.

The authors talk of how “caveats about the predation experiments discussed in Majerus’s book, critiques by other biologists, as well as points made particularly forcefully in a review of the Majerus book, were soon exploited by non-scientists to promote an anti-evolution agenda and to denigrate the predation explanation”. They add that “both the public in general and even evolutionary biologists began to doubt the bird predation story.”

Their paper also debunks the creationist ideas that arose when doubt was first cast on the idea of this rapid evolution of an animal as its surroundings changed through industrialisation and into the post-industrial world of the North of England. Moreover, industrial melanism is seen in other types of moth and provides parallel evidence for the changes observed in the industrial evolution of the Peppered Moth.

Poplar Hawk-moth, Laothoe populi

UPDATE: 25 Jun 2019 – Another Poplar turned up overnight along with two Privets, an Eyed, six Elephants, and a Small Elephant! And 150 other miscellaneous specimens.

My first taste of mothing proper was in a friend’s garden, where I turned up at about 8am the night after he’d “lit up” his 40W actinic, homemade, collapsable Robinson trap. I mentioned it on the blog at the time, you may recall – The Nouveau Mottephile. Regular readers will have noticed I’ve blogged about moths quite a lot since that fateful July morning. Anyway, on that morning I was startled by to be introduced to the diversity of the Lepidoptera, there were a few dozen moths in my friend’s trap, almost all of which I had never seen before. I only had a phone with me so, the photos I got were of poor quality. One of the most startling and beautiful moths in the trap is the subject of this post, the Poplar Hawk-moth (Laothoe populi).

The description on the UK Moths website about the Poplar Hawk-moth reads as follows:

“Probably the commonest of our hawk-moths, it has a strange attitude when at rest, with the hindwings held forward of the forewings, and the abdomen curved upwards at the rear. If disturbed it can flash the hindwings, which have a contrasting rufous patch, normally hidden.”

This specimen was in the trap this morning, the same trap, which I bought from my friend in the autumn of last year, having become hooked on mothing. It’s the first time I’ve seen this species since July 2018. I photographed it but obviously didn’t irritate it at all as it never flashed its underwings.

Other Hawk-moths that have featured on the blog:

Lime Hawk-moth, Mimas tiliae

Elephant Hawk-moth, Deilephila elpenor

Eyed Hawk-moth, Privet Hawk-moth, Small Elephant, Pine Hawk-moth, and Hummingbird Hawk-moth are in my Mothematics gallery.

As of 10 May 2022 yet to see or photograph: Death’s Head, White-lined, Convolvulus, Oleander, Willowherb, Spurge, Bedstraw, Striped, Silver-striped, Broad-bordered Bee, and Narrow-bordered Bee Hawk-moth.

Emperors, Admirals, and Chimney Sweepers

After much anticipation, Peter Marren’s new book – Emperors, Admirals & Chimney Sweepers (The weird and wonderful names of butterflies and moths) recently landed on my desk for review. One of the things I find most fascinating about the lepidoptera is their nomenclature, both the common names – such as Angle Shades, Lime-speck Pug, and Red Admiral, but also the scientific binomials including Aglais io, Autographa gamma, and Polygonia c-album.

Indeed, so fascinated was I that I put together a book proposal to write about how the butterflies and moths all got their names…but Marren had already beaten me to it and has done a far better job in writing about them than I ever could.

He explains the origins of almost every species you’re likely to come across in the UK. He tells us why the pug moths are called pugs (yes, it is to do with their resemblance in some characteristics to the flat-faced dogs). He explains that The Sprawler moth has a “star-gazing” caterpillar names after the Italian astronomer, Cassini. There’s also proof as to why the Common Wainscot is so named and it is indeed for the plain wooden panelling, as Mrs Sciencebase suspected when I presented that very moth in a pot a few days ago!

The infamous Death’s Head Hawk-moth, once a harbinger of doom, is in there as is the Jersey Tiger, the Emperor, and the Brimstone (both butterfly and moth). There are plenty of carpets too…which was never an insult as back in the day when these leps were named, having a carpet was a luxury, naming a patterned animal that recalls an elaborate carpet was therefore a compliment.

An excellent book for moth-ers and butterfly enthusiasts in the Little Toller Field Guide series. Highly detailed index makes it easy to look up the latest species that appears in one’s trap or is spotted in the garden our elsewhere – Cinnabar, White Ermine, Light Brocade, Garden Pebble, Waved Umber, Mottled Rustic and so on. There are well over 2500 species of lepidoptera in the UK and a few migrants and vagrants. Keep up to date with my own personal sightings and their names in my Mothematical Gallery.

Incidentally, there was a rumour that the proper name of the Red Admiral butterfly, Vanessa atalanta, is the Red Admirable. Even novelist and lepidopterist Nabokov insisted on this point. Marren discusses the etymology and in an update for the paperback, suggests that both words were probably in use very early.

Lime Hawk-moth, Mimas tiliae

The Lime Hawk-moth, Mimas tiliae, is fairly common in Southern England, especially where there are avenues of lime trees, in London, for instance. However, the species has headed north, extending its range in recent years. This specimen was drawn to actinic light in our garden on the night of 17th May 2019. Specimens have been found in North Yorkshire, according to UK Moths.

Lime Hawk-moth

Beautiful colours of greens and pinkish hues. although colour can vary considerably with a ruddier, rustier brown form out there too. The Lime Hawk-moth is a member of the Sphingidae, the Sphinx Moth family, which also includes the Hummingbird, Convolvulus, Privet, Elephant, Small Elephant, and Poplar Hawk-moths. Photos of specimens of Hummingbird, Elephant, Small Elephant (new 10th June 2019), Privet, and Poplar are in my Mothematical Gallery. 171 specimens as of 21st May 2019, with the addition of a new noctuid, Pale-shouldered Brocade, and a geometer, Oak Hook-tip, today.

I am hoping for Convolvulus, Eyed, and Deaths-head this year. In the British Isles, we have almost 20 species of Hawk-moth, also known as hornworms (because of the appearance of their larvae/caterpillars).

Counting on garden diversity, mothematically speaking

The range of moth species and the total number in and around the trap is picking up. Best night so far this year – 36 specimens of 21 species. There were a couple of species new for the year and at least one new to me.

Common Marbled Carpet
Common Marbled Carpet (Dysstroma truncata), new for the year
The Shears (Hada plebeja)
The Shears (Hada plebeja), new to me
Rustic Shoulder Knot (Apamea sordens)
Rustic Shoulder Knot (Apamea sordens)
Common Wainscot (Mythimna pallens)
Common Wainscot (Mythimna pallens), new for the year

The Shears (new to me, checking), Rustic Shoulder Knot, checking, Common Wainscot (NFY), Bee moth, Common marbled carpet (NFY), Garden carpet, SSD (4x), Common Pug, LBAM (3x), Brimstone, Muslin, Heart & Dart (2x), Turnip (4x), Twenty plume, Broad-bordered Yellow Underwing, Vine’s Rustic (5x), Common swift.

There were also three tiny, micro moths in the night two I have no photos and no clue, but one of them was very small and was perhaps this species: Apotomis betuletana, checking.

My Mothematics Gallery on Imaging Storm will have the latest lep stars with some details and their scientific names.

Pale tussock, Calliteara pudibunda

Long before I adopted mothing as one of the slightly weirder of my various hobbies (one that combines biology and photography with a bit of citizen science though), I still occasionally snapped lepidoptera if they turned up somewhere I had my camera. Back in May 2004, I caught sight of a huge, hairy moth in our conservatory. Got a snap and then spent ages trying to find out what species it was. Turned out to be Pale Tussock (Calliteara pudibunda).

The second time I saw one was 15 years later, on the corner of the actinic trap in the middle of May. As you can probably guess, it being the same month was no coincidence, the adults of this species fly May-June.

They’re a fairly common species in England and Wales, sexually dimorphic (the females are bigger and not so distinctively marked, but both have the forward facing hairy legs). According to the UK Moths site, the larvae feed on a range of deciduous shrubs and trees as well hops.

As ever you can keep up with the latest additions to my list either on my Moth Records spreadsheet or in the Mothematics Gallery on Imaging Storm.

Puss Moth, Cerura vinula

Last night was a very different night  of mothing. It had been up to 20 degrees Celsius during the day but got down as low as 7 degrees Celsius in the night, it was still and dry, with a waxing gibbous moon. The haul one gets to an actinic light moth trap can never be predicted, but numbers were the highest they had been since the warm patch in April 2019, it’s now mid-May 2019.

Puss Moth (Cerura vinula)
Puss Moth (Cerura vinula)

I was very pleased to see one of the larger British moths sitting on the outside of the trap this morning, the very furry Puss Moth, Cerura vinula. This specimen was an impressive 4.5 centimetres long from front leg to wingtip and has the most striking patterning.

As you can see from my photos it is very furry, has broad white wings. The forewings have very dark concentric lines that look like indentations, there are dark cross veins on the wings and bronze lines radiating down the thorax. This specimen also has a greenish hue to its heads and black spots. Gently coaxing it from the trap into an examination pot was quite an eerie feeling, the large size and furriness make you think you’re handling a small, alien-looking mammal, rather than an insect.

Puss Moth (Cerura vinula)

Also new for me, potted as it approached the trap last night was a Coxcomb Prominent, Ptilodon capucina, a species common from Ireland to Japan in the Palearctic ecological zone.

Coxcomb Prominent (Ptilodon capucina)
Coxcomb Prominent (Ptilodon capucina)

It was the busiest night for moths in the garden last night for a month or so, also ticked this morning and last night, 12 species, 20 specimens:

Puss Moth, Red Twin-spot Carpet, Hebrew Character, male Muslin (2x), Shuttle-shaped Dart (6x), Turnip Moth (2x), The Streamer, Double-striped Pug, Common Pug, Heart & Dart (2x), Light-brown Apple Moth.

Incidentally, I remember seeing photos of the Puss Moth caterpillar in books when I was a child, it was often the cover star of a wildlife book, for instance. You may recognise it too. Incidentally, don’t annoy this larva, it can spray formic acid at you…

Cerura vinula1

Heart & Dart, Agrotis exclamationis

Just added another new moth species to the mothematical list, the Heart & Dart (Agrotis exclamationis). Here’s a focus-stacked shot looking down on the moth so you can see its “darts” and its “hearts”.

Heart & Dart (Agrotis exclamationis)
Heart & Dart (Agrotis exclamationis)

Here’s a face-on closeup, also focus stacked using digiCamControl to capture a sequence of six photos at different focus positions, front to back, and then aligning and stacking together with CombineZP. The stacking has not worked brilliantly in this shot, the antennae have artefacts, but at least you can see this species’ distinctive black band visible only when looking at the front of the thorax head-on.

Heart & Dart (Agrotis exclamationis)
Head-on view of Heart & Dart (Agrotis exclamationis)

Apparently, the Heart & Dart is one of the most common of the so-called owlets, the Noctuid moths, common in Europe and widespread in the UK, attracted to light and its larvae (known as cutworms in this genus of moths). The larvae eat all sorts of garden and wild plants, turnip, potatoes, maize, spinach, strawberries, lettuce, beetroot, as well as oak leaves and brambles.

The moth’s common name is perhaps obvious, but so too, in some sense, is the scientific binomial: Agrotis from the Greek for farmer, exclamationis meaning an exclamation! A farmer’s exclamation. Not a species to be encouraged in one’s new #AllotmentLife.

Of course, some cultures get their own back on the plant-eating moths, by eating the moths themselves. The related Bogong moth (Agrotis infusa) is an icon of Australian wildlife due to its historical role as a food source for Aboriginal people of Southeastern Australia, Its gathering led to inter-tribal feasting. The moths are roasted to remove wings and scales and often made into moth meat paste, which apparently has a nice, nutty taste.