Category: Moths and Butterflies
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I started recording moths at our home, Bryn Llinos near Carmel (SN589164), in the spring of 2007, having been inspired by tales of a bumper year for moths in 2006 and a friend who set up his moth trap in my garden in May. The existence of a relatively cheap, really excellent, moth book (Waring, Townsend and Lewington, (2003)‐ Field Guide to the Moths of Great Britain and Ireland) was an added spur. Finally, there came a growing realisation, following the purchase of my first pair of spectacles, that if I didn’t start pretty soon, some of the finer detail of a moth’s plumage might soon begin to escape me! The book arrived a couple of weeks before the package containing my first moth trap, so I spent several evenings in mid‐June watching the kitchen window or the porch light, ready to pounce on an unsuspecting specimen and bear it triumphantly indoors to be identified. I added the first half a dozen species to a fledgling ‘garden list’ in this way. I realise now I should also have been out there searching any flowers I could find with a torch and perhaps even trying a little 'sugaring'. The trap (a Skinner‐type with mercury vapour [MV] bulb) duly arrived and, after a rather poor start on 21st June (six species), it 'came up trumps' three days later with 30 species. This proved to be the most species‐rich catch in a year when things soon started to go downhill fast as the weather deteriorated. By the end of the year I’d caught 110 species, the highlight being a Fern Horisme tersata, a moth with only a handful of records for Carmarthenshire. The larval food plant is wild clematis and this individual had perhaps drifted across from the mass of this plant some half a mile away in one of the old limestone quarries in Carmel Woods. Although the caterpillars are thought to feed on cultivated clematis too, the scarcity of records might suggest that this isn’t a very common occurrence.

Unrealistically confident that 2008 couldn’t possibly be as poor a year for moths as 2007, I started trapping at Bryn Llinos in March. Trapping with my MV trap is restricted to places within the 50m range of a mains extension cable but by borrowing a Heath trap, along with its rechargeable battery, I ventured further afield, particularly over the fence at the bottom of the garden and into the adjacent Carmel NNR. Without any planned programme, I simply put a trap out once or twice a week at Bryn Llinos or in the NNR whenever I had the time to check the catch in the morning and the weather looked promising for moths.

At Bryn Llinos, 2008 was a significantly better year for scarce moths. Pretty Chalk Carpet Melanthia procellata, another moth that feeds only on clematis, turned up a couple of times. The Tissue is extremely scarce in Carmarthenshire – almost certainly the one I caught had spent its early life munching on one of the buckthorn bushes in Carmel Woods. Another moth whose food plant has a restricted range is the Scorched Carpet Ligdia adustata – again it seems likely that the three I caught had made their way across from the spindle bushes in Carmel Woods. Scarce Umber Agriopis aurantiaria, Bordered White Bupalus piniaria and White‐marked Cerastis leucographa are all far more catholic in their choice of food plant, but all are scarce in the county.

Across in Carmel NNR, I trapped at four sites in the Garn area of the Reserve, an area of ancient woodland with sheltered fields and glades, plenty of woodland edge and several disused limestone quarries. Three of the trapping sites were either just inside the woodland or on the edges of glades. The fourth was in the centre of one of the large disused limestone quarries, now with a good range of grassland species after 100 years without quarrying. It was this trap site that turned up the two highlights of 2008: another Tissue and an Annulet Charissa obscurata, along with a Gold Spangle Autographa bractea. Having caught Scorched Carpet at home I wasn’t surprised to catch several closer to their food plant in the NNR. Blomer’s Rivulet Discoloxia blomeri is nationally scarce but may be increasing now that wych elm, its food plant, is making a comeback in Carmel Woods and elsewhere: two were caught. Scarce Umber was caught here too, as was a Grey Shoulder‐knot Lithophane ornithopus.

It’s interesting to make some further comparisons between the two years at Bryn Llinos; and between Bryn Llinos and the NNR.

At Bryn Llinos I caught 110 species of macro moth in 2007, between June and November, and 186 in 2008, between March and November. Looking only at the June to November period in each year gives a better comparison of moth activity: the figure for 2008 falls to 128 species. Trapping effort was similar over the June to November period in both years: the MV trap was used 33 times in 2007; in 2008 the MV was used 23 times, the Heath trap 8 times. Heath traps, which use an actinic light tube, generally attract significantly fewer moths but are recognised to be better than the more powerful MV lights at attracting some species. At least as good an indication of the health of moth populations is found by looking at the actual number of moths caught. For the June to November period this was 652 in 2007 and 892 in 2008. I make no claims for the rigorous application of ecological monitoring procedures but suggest that, considering species numbers too, 2008 was the better of these two poor years.

You might imagine that an ancient woodland NNR would easily out‐perform a hectare of secondary woodland, scrub, patches of wild flower meadow and garden, albeit one that I manage with a view to maximising structural and species diversity. The centres of my two trapping areas are only some 250m apart but there are several major differences. The NNR is on Carboniferous limestone, Bryn Llinos is on Old Red Sandstone (the boundary runs roughly through the middle of our garden). Differences in vegetation are, as you would expect, marked. Ash and hazel dominate the NNR, with calcicole shrubs and limestone grassland species including thyme. Bryn Llinos has a greater range of tree species (native and non‐native) including several conifers, wet areas and even a few patches of bilberry and heather.

Comparing numbers of individuals and species caught at Bryn Llinos and the NNR in 2008 is difficult: the period of trapping was a month longer at Bryn Llinos, the trapping effort at Bryn Llinos was greater than it was in the NNR and different traps were used. However it’s worth mentioning that 997 individuals were caught in the NNR (mostly in the Heath trap) and, with exactly twice the number of trapping sessions, 2191 moths were caught at Bryn Llinos (mostly in the MV trap). This suggests either that the Heath trap was performing better than might be expected alongside the MV, or that there were more moths to be caught in the NNR. The number of species recorded were: 186 at Bryn Llinos and 137 in the NNR. Perhaps next year a better comparison could be made by following a better planned trapping programme. One thing does stand out however: the top 5 most numerous species are all different for the two sites. At Bryn Llinos the two years combined give a total of 206 species with the top five commonest being Hebrew Character (325 individuals), Brimstone Moth (138), Clouded Drab (116), Common Quaker (106) and Common Marbled Carpet (97). In the NNR in 2008 it was Brindled Beauty (63), Small Phoenix (62), Large Yellow Underwing (52), Ingrailed Clay (42), Mottled Beauty (40). Some of this variation could be due to the different trap type but most seems likely to be down to the difference in habitat.

Clearly it’s far too early to make any meaningful comparisons between the two sites but I hope over the next few years to build up far more data, monitor in particular the scarcer resident species and perhaps begin to see what effect management of both sites has on moth populations.

Thanks to The Grasslands Trust for permission to trap in the area of Carmel NNR which they manage, to Jon Baker, County Moth Recorder, for checking some of the rarities from my rather poor digital photos and to Ian Morgan for much encouragement.