The Joys of Moth Trapping
A Heath trap, the smallest and most convenient of the three most widely available trap types and suitable for back gardens.
Insects and creepy crawlers are not universally liked, spiders typically bearing the brunt of most peoples’ ire. There’s always been a great exception to this – butterflies (and caterpillars), though their close relations - moths, don’t seem to get such good press. Afterall many people associate them with eating holes in gran’s old clothes stuffed at the back of the wardrobe. But did you know that whilst there are only around fifty species of butterfly in the UK there are actually more than two thousand species of moth with a staggering amount of diversity.
The largest resident hawkmoth in the UK - the Privet Hawkmoth (Sphinx ligustri) makes for an impressive catch in the trap and are actually quite common. 105mm 1/160s F11 ISO 320 (Nikon D7200).
It isn’t surprising if you don’t because the vast amount of them fly at night, not during the day, and some are very small. The best way to get to see them is by using a moth trap, the topic of today’s blog, a simple UV light emitting device which can be setup in your garden or a local field. There are three types of moth trap widely used: Robinson, Skinner & Heath. The Robinson & Skinner traps use a more powerful light so typically catch more moths but will almost always be run off mains power. The Heath trap which I use (a picture of which you can see heading this blog) is the smallest and most convenient and can even be run off battery power (though mine still uses mains electric).
The inside contents of a moth trap. Egg boxes give the moths inside something to settle on and pieces of kitchen roll help absorb any excess water.
The funnel through which the moths come down from the light into the trap. Sometimes a few moths rest on here instead of the egg boxes.
A Garden carpet (Xanthorhoe fluctuata) rests on an egg box. 105mm 1/200s F8 ISO 64.
No one knows exactly why moths are attracted to light at night (I am sure you’ve all seen moths flying around the lamppost outside your house) but drawn in by the light they tumble down the funnel into the small openings of the box where they eventually rest in the empty egg boxes left inside. In the morning you can then open it up and see what you’ve caught. Warm, humid nights with cloud cover are always the best as dry, cold and cloudless nights lead to lower levels of activity or in the case of a bright moon, more distractions from your trap. In fact, I would say there isn’t much point in trapping on a night that drops below 10°C, though putting it out during a heavy thunderstorm is obviously not advised either.
A Red-green carpet (Chloroclysta siterata) on a suitably red-green background. 55mm 1/4s F11 ISO 100 (Nikon D3200).
The best way I can describe moth trapping is as lucky dip for adults. Though you mostly get what you would expect for that time of year there’s always surprises that pop up and catching your first hawkmoth in the spring is always exciting. June is perhaps the best month as you get a wide variety of species but lower numbers per species. July is the peak, but you can get vast numbers of a single species like the Large Yellow Underwing (Noctua pronuba) which at times can be a real nuisance. May, August & September are also good months but late autumn through to early spring often has low numbers and many fewer suitable nights for trapping. That’s not to say there isn’t anything to catch however, as unlike butterflies, moths can be found all year round. Whilst on the face of it this seems odd, when you consider their main predators are bats which hibernate in the winter it’s a clever evolutionary strategy to emerge when they do not.
The Merveille de Jour (Dichonia aprilina) is an autumnal moth that has fantastic camouflage that makes it hard to spot on the lichen. 25mm 13s F11 ISO 100 (Nikon D3200).
Up close you can really appreciate it’s patterned beauty. 55mm 15s F11 ISO 100 (Nikon D3200).
Sadly 2021 has not been a particularly good year for moth trapping so far. Much like the flowers & plants I talked about in last week’s blog, the very dry April, wet May, and persistent frosts up until the start of the latter has really set back numbers. Thankfully though with the consistently better weather we have recently had a lot more has been emerging and it looks like we are back up to the kinds of numbers we would expect in June. Fingers crossed this continues throughout the year.
This Beautiful Plume Moth (Amblyptilia acanthadactyla) gives an idea of the diversity of forms that moths can take and is one of the more easy identifiable micro moths. 46mm 1/200s F8 ISO 400 (Nikon D3200).
Moths are a great ecological indicator which can tell you a lot about both the types of plants in your local vicinity as well as the quality of the air. Some species, such as the Silver Y (Autographa gamma), are migrants that get blown over from the continent, so they can even tell you a bit about recent weather patterns. Above all though it’s just a bit of fun and gives you a chance to marvel at a part of nature that is so often overlooked or that flies under the radar (come on, it’s been a while since I’ve made a bad joke you can give me that one!).
It isn’t just moths that can turn up in the trap beetles like this Cockchafer (Melolontha melolontha) also make an appearance during certain times in the year.
If you fancy having a go at trapping in your own garden or outside space, then I do recommend checking out this website linked here: https://www.angleps.com/. They are a UK based company and one of the best, as it sells everything you could possibly need and more. In addition, it also has free downloadable guides on how to start moth trapping. The go to books for moth identification are:
Field Guide to the Moths of Great Britain and Ireland (3rd Edition): https://tinyurl.com/bsbprcjv
Field Guide to the Micro-Moths of Great Britain and Ireland: https://tinyurl.com/2eh8exd3
Concise Guide to the Moths of Great Britain & Ireland (2nd Edition): https://tinyurl.com/7fvzpcpw
The concise guide is a shorter version of the first book but still contains drawings of every moth by the fantastic Richard Lewington. In addition to the books, I recommend you check out the many Facebook groups for moth identification as it can be very daunting starting out without any prior knowledge. Otherwise, happy trapping and let me know if you have any questions or thoughts in the comments section below.
A Pine Hawkmoth (Sphinx pinastri), I caught these for the first time in 2020. 105mm 1/125s F8 ISO 250 (multi-image focus stack).
One of my favourites and one I have only ever caught one of so far - a Lime Hawkmoth (Mimas tiliae). 105mm 1/80s F11 ISO 64 (multi-image focus stack).
Moths like other insects make great subject for macro photography with all their interesting fine details - Mottled Umber (Erannis defoliaria). 105mm 1/20s F11 ISO 64 (multi-image focus stack).
One of the prettiest moths you can catch, the brightly coloured Small Elephant hawkmoth (Deilephila porcellus). 105mm 1/50s F5.6 ISO 250 (multi-image focus stack).
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