Category: Science

I helped out at my first public moth event and bioblitz on 1st July at the wonderfully serene Coton Orchard, a couple of clicks west of central Cambridge.

It’s a mature and well-established early twentieth century orchard with great soil and a lot of biodiversity, Anna Gazeley told me at the event. Plenty of wild blackthorn growing on patches that no longer host apple trees and several areas of rewilding and meadow creation underway. There were dozens of Marbled White, Small Skipper, Meadow Brown, and Small Heath butterflies enjoying the meadows while Buzzards circled the thermals overhead.

Coton Orchard is, unfortunately threatened by what can only be described as a wholly inappropriate, costly, and ten-years out-of-date transport-infrastructure project for Cambridge. All in the name of sustaining Cambridge’s purported 15-minute city ethos. It looks like a very misguided busway idea to me and many others, despite what the developers and some members of the council claim. Indeed, the 2020 biological survey of the site suggests that the development would have a very detrimental effect on the ecosystem and the wildlife. Purported offsetting of the harm by planting new trees elsewhere does not and never can compensate for destroying established systems. It’s greenwashing at its worst.

Anyway, there was a good crowd of people of all ages who turned up quite early on a Saturday morning to see the grand unveiling of the moth traps. There were a lot of species, Privet Hawk-moth, Elephant Hawk-moth, Lunar-spotted Pinion, Dark Umber, Heart & Dart, Heart & Club, Dark Umber, Marbled Orchard Tortrix, Small Emerald, Silver Y, Bordered Straw, lots of micros, and many, many more from three actinic and one mercury vapour bulb trap. Those big moths delighted young and old alike!

I, and the proper moth experts there (Adrian Matthews, Ben Greig, Jim Cox, Lois Clarke, and others), talked to members of the public who were curious about various aspects of the moths, especially the names of different species.

I kept an eye on what was being revealed in each trap and was quite surprised, but encouraged, to see that I recognised a lot of the species from my own garden mothing over the last five years. There were dozens of species and hundreds of moths all enjoying their life in and around the orchard, I’m sure. Some were more rare than others, like Small Emerald and Dark Umber, and there may well be rarities at the orchard too that didn’t find the traps but were among the trees and in the undergrowth. Of course, there were lots of Apple Ermine moths. The team there is hoping and waiting to see the super-rare Black Hairstreak butterfly on the wild blackthorn on this site.

Also, there was entomologist Claire Wallace who pointed out that she could see that a sample had been taken for genetic testing from one of the beetles (a Sexton Beetle) found in one of the traps.

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UPDATE: I helped out at a public moth event and bioblitz this morning at the wonderfully serene Coton Orchard, 2-3km west of central Cambridge. It’s a century-old orchard with great soil and a lot of biodiversity, Anna Gazeley told me at the event. It is, unfortunately threatened by what can only be described as a wholly inappropriate, costly, and ten-years out-of-date transport-infrastructure project for Cambridge. All in the name of sustaining Cambridge’s purported 15-minute city ethos.

Anyway, there was a good crowd of people of all ages who turned up quite early on a Saturday morning to see the grand unveiling of the moth traps. There were a lot of species, Privet Hawk-moth, Elephant Hawk-moth, Lunar-spotted Pinion, Dark Umber, Heart & Dart, Heart & Club, Dark Umber, Marbled Orchard Tortrix, Small Emerald, Silver Y, Bordered Straw, lots of micros, and many, many more from three actinic and one mercury vapour bulb trap.

I, and the proper moth experts there (Adrian Matthews, Ben Greig, Jim Cox, Lois Clarke, and others), talked to members of the public who were curious about various aspects of the moths, especially the names of different species.

I kept an eye on what was being revealed in each trap and was quite surprised, but encouraged, to see that I recognised a lot of the species from my own garden mothing over the last five years. There were dozens of species and hundreds of moths all enjoying their life in and around the orchard, I’m sure. Some were more rare than others, like Small Emerald and Dark Umber, and there may well be rarities at the orchard too that didn’t find the traps but were among the trees and in the undergrowth. Of course, there were lots of Apple Ermine moths. The team there is hoping and waiting to see the super-rare Black Hairstreak butterfly on the wild blackthorn on this site.

Also, there was bee expert Claire Wallace who pointed out that a sample had been taken for genetic testing from one of the beetles (a Sexton Beetle) found in one of the traps.

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If you’ve been visiting Sciencebase for a while, you will know that in July 2018, I acquired a moth trap, became quickly fixated on this other world of nocturnal Lepidoptera, and have logged and photographed the species that turn up in my garden and that I see elsewhere ever since. Almost fanatically, Mrs Sciencebase would say…

I did an audit of my logs at the end of June ahead of my five-year anniversary as a moth-er on 24th July. So, I’m writing this post on the 30th June and will update as July gets underway.

At the time of writing, I have recorded 448 moths in my South Cambridgeshire garden, mainly drawn to a 40W actinic light over the years, but occasionally and regularly for a month or so to a (cheaper-to-run) 20W Wemlite, an even-cheaper-to-run LepiLED, or to various pheromone lures. There has been the occasional moth that turned up without my having done anything, The Vapourer and the Lilac Beauty, for instance. The former on our bedroom window one afternoon (spotted by Mrs Sciencebase), the latter perched at the front door (spotted by me).

I have also recorded 34 species elsewhere, either random sightings on nature reserves, in woodlands, or in holiday house gardens. I have also photographed 38 species of British butterfly (butterflies are moths) and ten species outside the UK. So, in total, well over 500 species of Lepidoptera.

It’s the garden moth list that I focus on, however, I was hoping to reach 500 species of moth in the garden for my fifth anniversary, that seems unlikely unless there’s a big change in conditions and wind and weather in the next three weeks that brings some newbies in.

In my first year (2018), I saw approximately 127 species new to me. I had obviously seen a few moths in my life before that. In 2019, the NFM list was 125, in 2020, when we had a run of very warm days and cold March nights, I only ticked 30 new species in the garden. For 2021, that number was 38. Things picked up considerably in 2022 and despite that fact that I was basically seeing mostly the same moths year after year, I recorded more diligently the micro moths and the macros too and had 64 new species, with Convolvulus Hawk-moth (attracted to my Nicotiana flowers) and the wonderful December Moth (also in late September) being the highlights of that season.

At the time of writing, I’ve recorded 19 new species in the garden and one elsewhere, Brindled Twist, which was in the local Les King Wood sitting next to a fairly rare Pyramidal Orchid.

So, as of 30th June, 482 (non-butterfly) moths and just 34 of those not in the garden. Incidentally, I have ticked only one new butterfly species so far this year, Dingy Skipper at Devil’s Dyke. In the previous two years, I’ve seen 6 new species each year. I am hoping to add one or two more to that short list in 2023, but it may not happen.

As I approach my fifth anniversary as a mother, my tally shows that I have recorded and photographed almost 500 species. The most recent was new to my garden – The Leopard Moth, Zeuzera pyrina.

There are several things of interest about this moth aside from the fact that it’s fairly large and white with spots of black (almost metallic blue, in some cases). First is that the adults, the flying creatures, as opposed to the larvae (caterpillars) have no working mouth parts and so cannot eat. There are several other species, such as the Emperor, which are in a similar predicament, as it were. They are to all intents and purposes flying sex machines and nothing else, to be frank.

A second point of interest to me, is that with a quick glance you can see that the males have feathered sensory antennae, they resemble those of the Willow Beauty males. But there is an important difference in structure. Where the Willow Beauty antennae resembles a feather along its length, the Leopard’s antennae are feathered half-way along their length and seem to end in a bare spine.

Now, the really interesting thing about the Leopard Moth, as pointed out to me by uber-mother Leonard Cooper, is its lifecycle. Once mated, the female lays clutches of eggs in damaged areas of bark in the larval foodplants (deciduous trees). The larvae hatch from the eggs and begin burrowing deeper into the wood, they tunnel out feeding galleries, eating wood (they’re xyophagous) and leaving frass (poo) in their wake. If the adults are flying sex machines, then the larvae are burrowing food machines.

Once they’ve had their fill and by some conditional trigger, the larvae burrow through the wood and then pupate just under the bark. Presumably, they find a damaged patch so that once they have completed their metamorphosis within the pupal form and are ready to emerge as adults, they can spread their wings and fly off to find a mate. To do so they will use up the food reserves built up during the time they were very hungry caterpillars. In the UK, you might see adults in flight from June to July.

Oh, when I said “very hungry caterpillars, they can spend two or three years feeding in the galleries they create within the stems and branches of the tree before pupating. Now, several moths overwinter as larvae or pupa. The Leopard is not quite exceptional in that it lives so long as a larvae, perhaps up to four years rather than just 2-3 years, the Goat Moth, too spends a long period within the trees, I am sure there are others.

As to my mothing for five years, do you seriously think I am looking for a new pastime? Do Leopards ever change their spots?

This is a female Box-tree Moth. They were inadvertently brought into the UK in 2007 on imported, exotic Box plants. They are spreading rapidly and I see lots in Cottenham. I don’t think they’ve got as far north as Ely yet, but it’s only a matter of time.

The female lays her eggs on Box plants and her larvae will ravage the plant, you’ll see the damage pretty quickly. In their native environment the moths are kept in check somewhat by the ecosystem itself, but that doesn’t happen here. I have warned people not to plant Box here any more…it will be eaten…even established hedges will succumb. Please don’t spray pesticides around, pesticides are nasty, and I say that as a chemist. If you really want to try and save the hedge pick the caterpillars off by hand and “relocate” them…

You can buy a pheromone trap, a plastic flask, often green and yellow, and you put a little rubber bung in the top. The bung carries a tiny quantity of the female sex pheromone. You hang it near your beloved Box hedge and it attracts the males who are suckered into going into the trap thinking a female awaits…they can be drawn in from up to about ten miles away.

Sounds like a cunning plan, doesn’t it? But, think about it. The females are all over the place, and most likely on your hedge, to which they’re drawn because it’s their larval food plant (hence the name!). There may well not have been males in your street, but you’ve just put out a big chemical communication and invited them to the orgy…even if you catch a handful in the trap before they mate, chances are you won’t catch them all, and it only takes one for your local female to have a clutch of fertilised eggs ready to lay on your hedge. Her very hungry caterpillars will feast on it soon enough…

You can distinguish between the male and female moth, because the males have a tuft at the end of their body known as a hair pencil, it’s basically a diffuser for their own pheromones. There is also a melanic form of this species, which is dark brown-purple where this one is white.

I acquired another moth trap to go alongside my old second-hand, home-made Robinson with the 40W actinic UV fluorescent U-tube, the portable 20W UV fluorescent Heath, the LepiLED, and, of course, the pheromone trap for the Emperor moth and the clearwings.

I crammed it with the usual stock of roosting options for the moths, a load of empty cardboard egg cartons, and lit up.

It was 11 Celsius last night, a degree cooler than a recent lighting-up session, but the new trap brought a fairly good haul, 28 moths of 18 species, with several new for the year (NFY), although no new for me or new for the garden (NFM or NFG). These are the highest numbers of the year so far, although the good numbers on nights of a similar temperature recently have not been far short.

The Skinner trap is basically a box with slots in which two Perspex sheets are slid to form a groove with a narrow gap. A UV light is held above. Moths (and a few other nocturnal insects) are attracted by the light and with luck fall through the slot and on to the pile of egg cartons where they settle for the night. In the morning, preferably before dawn when insectivorous birds awaken, the diligent mother-er will check the contents of the trap. Not species and number, perhaps take photos, and then later in the day release the moths safely, off-site into the new dusk. Records are shared with one’s County Moth Recorder (CMR) for scientific purposes.

The Heath and the Robinson traps are similar, but have a funnel instead of a slot, which purportedly leads to fewer escapees. The Heath is usually small collapsible, and so more portable than a Robinson.

This is the quite diverse list from last night’s haul, one each of each moth unless otherwise stated: Bee Moth, Brimstone, Celypha striana NFY, Common Pug, Garden Rose Tortrix NFY, Heart & Dart 4, Large Nutmeg, Light Brown Apple Moth, Light Arches NFY, Light Brocade 2, Light Emerald 1, Minor agg 2, Shuttle-shaped Dart 2(M), The Shears NFY, Toadflax Brocade NFY, Vine’s Rustic 3, White Point 3, Willow Beauty 1.

There are some who argue that this hobby, albeit a scientific one, is somehow cruel. That we are depriving creatures that live only a short life of one night of their season. And, that we should leave them to themselves. Well, far more cruel is the wanton destruction of the habitats in which these creatures live and the often shameless use of pesticides.

However, without people monitoring species, keeping records, collating them, and studying the trends, we would not have a clue as to what we need to protect from the destruction, and how we might do that. We know from these mothing records that many species have declined considerably over the last half century or more. But, we also know that some species once thought extinct have thankfully risen from the scorched fields to grace our gardens and other habitats again. We also now know more about how some moths migrate and where from. In addition, we also know, often from the pheromone trapping, that some moths, the clearwings and various micro moths, once thought absent in particular areas are present there after all and perhaps more widespread than we ever imagined.

Oh, and one more thing. A bat will consume 300 or so flying insects every night, so the impact of even the most efficient and effective moth trap in the garden is negligible in comparison. Indeed, one might say, they are saved from predation if they find those egg cartons before the bats find them!