Moths In My Garden

by Bill Welch.

Swallow-tailed Moth, Ourapteryx sambucaria.
Garden trap in Hayes, July 2012.

A few years ago I started going along to natural history walks and events run by Bromley Council. I was lucky to start when I did, because soon after that the council stopped running their events following government-imposed cutbacks. But a couple of the events I went to were to do with moths. One was a night trapping event on Keston common. After that, I realised I had become intrigued.

Moths turned out to be many and varied, and invisible until they came to the bright light of the moth traps. It seemed half-magical, like drawing out the night's secrets. I sought out some other moth trapping events, at Farthing Downs and Sevenoaks Wildlife Reserve, and eventually decided that I would get my own moth trap and see what could be enticed out of the darkness in my own garden.

This sounded like fun. And what's more, I like photographing insects (and other things) and this way I would not even have to search them out; they would come to me! All the moths are released after photography, so this type of trapping is not destructive.

Now, my garden is a tiny thing on the edge of suburbia, near the railway station in Hayes, Kent. There are woods not far away, but not near enough for wood moths to come to my trap. And I could not put out a really bright trap, because I had the neighbours to think of. So I got hold of a Skinner trap with a 15 watt actinic light. The trap is little more than a square box about 16 inches on a side, with some egg boxes for moths to shelter in, and the light is not much brighter than those decorative garden lights you sometimes see; at least, not to the human eye. But it also puts out ultraviolet light, which attracts at least some moths.

Beautiful Plume, Amblyptilia acanthadactyla.
Computer room in Hayes, August 2012.

Brimstone Moth, Episthograpta luteolata.
Above garden trap in Hayes, September 2012.

So this is not exactly the arrangement most likely to deliver a healthy array of moths. Yet, over 2012, my first full year of garden trapping, I saw 109 different species of moth, more or less evenly split between macromoths and micromoths, plus a few I couldn't identify.

I put my trap out two or three times a week when the weather was suitable; at least a few degrees above zero, and not actually raining. You can probably imagine that in 2012, the wettest year on record in England, that was not always achievable! At the start of the year, there were very few moths, mostly winter specialists, but as soon as the weather warmed up they started to arrive in greater numbers. I found I was also able to identify moths I found in the house, and those that flew into my computer room on warm summer nights.

The commonest species to come to my trap will be well known even to beginners. Large Yellow Underwing, Pale Mottled Willow, Willow Beauty, Lesser Yellow Underwing, Flounced Rustic. But I also saw some prettier ones; Brimstone Moth, Least Carpet, Treble Lines. And there were occasional specimens of greater interest or beauty. Not rare, but perhaps unusual in suburbia.

Jersey Tiger, Euplagia quadripunctaria.
Garden trap in Hayes, August 2012.

Tree-lichen Beauty, Cryphia algae.
Garden trap in Hayes, August 2012.

These included a Blue-bordered Carpet, a Buff Ermine, a Black Rustic, a Tree-lichen Beauty, a Swallow-tailed Moth and two specimens of the Jersey Tiger, a vividly coloured moth that has only recently begun to spread in this area.

Those are all so-called macromoths, species which are mostly among our larger moths. Macros are relatively easy to identify. There are about 800 British species, and of these, only a few groups are hard to tell apart with the naked eye. And I had a lot of help at the start from Gill Peachey, a volunteer at Farthing Downs. Then, part way through the year I got hold of a new book, a field guide to micromoths.

That opened up a whole new area of knowledge, though how good that knowledge was is a little suspect. There are about 1600 British species of micromoth. Many of these are hard to tell apart, yet it is very tempting to "identify" a micromoth from appearance alone that actually looks a lot like several other species, so that the identification is not solid. I know that many of my micromoth identifications are good, but equally, many are still shaky. I was lucky to discover the Open University's iSpot site, from which I got a lot of help with my micro identifications.

Mother of Pearl, Pleuroptya ruralis.
Garden trap in Hayes, September 2012.

The so-called micromoths actually include some species that are larger than some macromoths. For example, the iridescent Mother-of-pearl and several of the Plume Moths. I was entranced by one Beautiful Plume that flew into my computer room one night, rather like a flimsy microlight in comparison with the stukas and jet planes of some of the macros. It was so slow that I was able to catch it directly in a specimen tube from mid-air, and photograph it on my measuring paper.

The trap also pulled in quite a few other sorts of insects. Wasps quite like the light, and need to be watched out for; some mothers find hornets in their traps, even more dangerous. Some flying beetles will come to the trap, including big cockchafers in season. There were plenty of caddis flies, easily confused with moths by beginners. Also various other flies, and spiders and harvestmen, some of them probably just finding decent shelter and not affected one way or the other by the light, and some probably predating on the insects.

I am told that 2012 was a poor year for moths, too wet for many of the larvae to thrive. 2013 is not shaping up to be a good year either. But even in a bad year, there is plenty of interest and learning to be had from a simple moth trap.

The cross-hatched background to some of my photos is measuring paper with squares 5mm across, indicating the actual and relative size of the moths. For example, by counting the squares you can see that the Jersey Tiger is 3 cm from head to wing-tip and is twice as big as the Beautiful Plume and the Tree-lichen Beauty.

Scientific names of the moths mentioned above: Large Yellow Underwing, Noctua pronuba. Pale Mottled Willow, Paradrina clavipalpis. Willow Beauty, Peribatodes rhomboidarea. Lesser Yellow Underwing, Noctua comes. Flounced Rustic, Luperina testacea. Brimstone Moth, Opisthograptis luteolata. Least Carpet, Idaea rusticaria ssp. atrosignaria. Treble Lines, Charanyca trigrammica. Blue-bordered Carpet, Plemyria rubiginata. Buff Ermine, Spilosoma lutea. Black Rustic, Aporophyla nigra. Tree-lichen Beauty, Cryphia algae. Swallow-tailed Moth, Ourapteryx sambucaria. Jersey Tiger, Euplagia quadripunctaria. Mother-of-pearl, Pleuroptya ruralis. Beautiful Plume, Amblyptilia acanthadactyla.

The best books for field identifications of moths: for macromoths, "Field Guide to the Moths of Great Britain and Ireland," by Paul Waring and Martin Townsend, illustrated by Richard Lewington. British Wildlife Publishing, Revised (second) edition, 2009. For micromoths, "Field Guide to the Micromoths of Great Britain and Ireland," by Phil Sterling and Mark Parsons, illustrated by Richard Lewington. British Wildlife Publishing, 2012.