Westcott, Bucks - the year 2015 in review

The appearance of no less than 653 species of lepidoptera here at Westcott during 2015, a record yearly total for the garden, was certainly unexpected and very much at odds with how the year seemed to be progressing, certainly up to its half way point.  The first six months proved to be exceedingly disappointing for all insects.  While most of the expected species did put in their usual appearances, abundance was hit badly by the poor weather and few butterflies or moths were seen in any significant numbers.  A change to the weather conditions at the very end of June resulted in a significant improvement for much of July, but unfortunately it didn’t last and August proved to be another disappointment.  We did have a relatively mild and pleasant autumn, which in fact persisted throughout November, but by then it was too late and no significant recovery was noticed although there were a few out-of-season appearances from species which had presumably become totally confused by the weather.  It was migrants from across the Channel which provided the main focus of excitement in 2015, with the prevailing winds favouring the movement of insects (moths in particular) from continental Europe into the UK for much of the period between May and November.  Being so far from the coast, Bucks doesn’t usually do all that well even in good migrant years but this time the garden here certainly seemed to get its fair share of interesting species.

Butterflies:   

It was a particularly disappointing year for butterflies.  20 species were seen (down slightly from 22 in 2014) out of a total of 30 which have been recorded in the garden since the millennium.  The only significant records during 2015 were of White-letter Hairstreak Satyrium w-album which appeared again on our elms during the first two weeks of July.  Holly Blue Celastrina argiolus seemed to recover somewhat after its dismal showing the previous year but there wasn’t really any other good news.  The biggest disappointment was the general lack of vanessid species on our buddleias in July and August, with counts of Peacock Inachis io barely getting into double figures at any one time whereas the normal expectation would be a peak of 50-60 individuals.  Despite all the cross-Channel moth activity it didn’t turn out to be a bumper year for butterfly immigrants but there were regular sightings of Painted Lady Vanessa cardui in the garden between the last week of July and the second week of September.

 

Small Whites, 8th April

Painted Lady, 21st August

 

 

Moths:   

As mentioned in the first paragraph, the most noticeable thing about moth activity in the garden during 2015 was reduced counts for many species, especially when one takes into account the extra amount of recording carried out here during the year.  The trap was run on 295 nights, the majority of missed nights occurring during January (25), February (19), November (7) & December (10) because of inclement weather.  As usual the favoured device was a single twin-30wt actinic Robinson trap.  The 125wt MV Robinson replaced it on 42 occasions while, in a departure from previous practice, both the actinic and MV were run together on a further 48 nights (all of them between 13th June and 10th October) with a hedge separating the two light sources.  Using the two different trap types at the same time certainly seemed to pay dividends.  100 or more species were recorded on 16 occasions between 30th June and 22nd August, always on nights when both types of trap were run, with the highest species count (152) being achieved on 3rd July.  That compares to just a dozen 100+ nights in 2014, although those were all just to a single trap.  The highest single-night garden catch in 2015 was 988 moths (on 16th July).  The site total for the year was 33,803 individual moths, that number being only slightly up on what was achieved in 2014 (32,472) even though in excess of 25% more trapping effort was put in this year.  As usual, all catches were released at least half a mile away so the chance of recaptures was practically nil. 

Following a run of poor years here, Large Yellow Underwing Noctua pronuba recovered to become the most numerous moth caught, although its final total of 2,014 for the year seemed to be achieved very stealthily because high counts on a single night were few and far between.  It was as usual present over a long period (9th June to 6th November), the greatest number of individuals recorded being on 8th September when 79 were seen, but most nightly counts were of fewer than 50 even when two traps were employed.  Lunar Underwing Omphaloscelis lunosa achieved second place with 1,644 individuals but that figure was less than half of its 2014 count.  Heart and Dart Agrotis exclamationis took third place with 1,515 recorded, although that was again down considerably from the 2014 total.  Fourth place was again achieved by one of the ‘grass moths’, this time Agriphila tristella with a count of 1,046.  Left out of the tables in this and previous years have been those species for which the majority of sightings are recorded as an aggregate, such as Common Rustic/Lesser Common Rustic and Uncertain/Rustic.  While the Hoplodrina pair probably appear in roughly equal numbers, the same is unlikely to be true of Common Rustic Mesapamea secalis and Lesser Common Rustic Mesapamea didyma.  The combined total for this pair in 2015 was 1,535, the highest figure they’ve ever achieved in the garden, and it seems certain that well over 90% will have been secalis so in reality that species probably took third place in the league table.     

 

	Top 20 Highest Counts
20	Setaceous Hebrew Character	360
19	Beaded Chestnut	385
18	Small Square-spot	391
17	Lesser Broad-bordered Yellow Underwing	406
16	Flame Shoulder	443
15	Common Footman	449
14	Agriphila straminella	453
13	Hebrew Character	458
12	Brimstone Moth	540
11	Eudonia mercurella	675
10	Pleuroptya ruralis	703
9	Acentria ephemerella	811
8	Square-spot Rustic	811
7	Smoky Wainscot	835
6	Chrysoteuchia culmella	837
5	Dark Arches	909
4	Agriphila tristella	1046
3	Heart and Dart	1515
2	Lunar Underwing	1644
1	Large Yellow Underwing	2014

 

While by far the majority of species appeared with lower counts in 2015 than in previous years, as usual there were a few good-news stories.  With the exception of Agriphila straminella which dropped back to less than half its 2014 total, the ‘grass moths’ did particularly well, as did Mother of Pearl Pleuroptya ruralis.  Single-dotted Wave Idaea dimidiata (122 individuals) doubled its previous best yearly total, while Small Elephant Hawk-moth Deilephila porcellus (115) also achieved its highest ever count here, beating by a significant margin the 71 seen in 2005.  Some, but by no means all, of the autumn species also did very well and those worthy of particular mention are Red-green Carpet Chloroclysta siterata (91), Dark Chestnut Conistra ligula (86) and Brick Agrochola circellaris (156), all of which achieved their best ever totals.

Macros:  
 

324 different macro-moth species were seen here between January and December 2015.  That count in itself was a big surprise (beating last year’s record of 307 by a significant margin) but the 2015 total included 13 completely new species for the site and takes the garden’s all-time macro list up to 411.  The year’s newcomers were as follows:   

1790	Tissue (Triphosa dubitata)	4 August
1856	Larch Pug (Eupithecia lariciata)	15 June
1894	Latticed Heath (Chiasmia clathrata)	2 August
1993	Silver-striped Hawk-moth (Hippotion celerio)	4 July
2038	Muslin Footman (Nudaria mundana)	10 July
2281	Alder Moth (Acronicta alni)	12 June
2338	Rufous Minor (Oligia versicolor) *	23 July
2408	Small Marbled (Eublemma parva)	3 July
2412	Silver Hook (Deltote uncula)	6 July
2422	Green Silver-lines (Pseudoips prasina)	30 June
2432	Ni Moth (Trichoplusia ni)	9 August
2463	Burnet Companion (Euclidia glyphica)	7 June
2476	Beautiful Snout (Hypena crassalis)	1 July

* confirmed via dissection by Peter Hall 

There are about 20 previous records for Tissue in Bucks and most of them are from the northern half of the county.  Conversely, its stablemate Scarce Tissue Rheumaptera cervinalis, for which there are three times as many records, seems confined mainly to the southern half so that’s perhaps a species unlikely to be seen in the garden here.  Although common wherever the food-plant is available, Larch Pug was a nice find here and was recognisable without the need for dissection, thanks in particular to the markings on its thorax.

Tissue, 4th August

Larch Pug, 15th June

The Silver-striped Hawk-moth, Small Marbled and Ni Moth were undoubtedly migrants from Europe (see later) but there must also have been a good deal of domestic moth dispersal to bring in visitors such as Muslin Footman, Silver Hook and Beautiful Snout, none of which would really be expected around here in a ‘normal’ year.  Muslin Footman, which is rarely encountered in Bucks, was found in the garden twice (on 10th and 19th July) and during the intervening period I recorded it while trapping in two nearby areas of woodland.  It must have undergone quite a significant movement from its usual habitat, remarkable really for what at first sight appears to be a weak flyer.  The Alder Moth on 12th June marked a welcome milestone in that it proved to be the garden’s 400th macro-moth species. 

Muslin Footman, 10th July

Alder Moth, 12th June

Silver Hook is a moth of marshy areas and has been recorded on six previous occasions in Bucks, all of them prior to the millennium.  The most recent sighting (in 1993 at the Prestwood Picnic Site) was similarly out of its normal habitat.  The regal-looking Beautiful Snout is understood to feed on bilberry and heathers so, of the 13 previous records for Bucks, those from Aspley Heath, Black Park and Stoke Common should come as no great surprise.  However, finding it at Westcott (and in Bernwood Forest, where I had another to light on 10th July) is difficult to explain other than by dispersal.

Silver Hook, 6th July

Beautiful Snout, 1st July

 

Latticed Heath is mainly a daytime flyer and, unlike Common Heath Ematurga atomaria, is a moth not seen all that often locally, so getting two examples to light at night (on 2nd & 14th August) was perhaps a little unexpected.  The other first-timers, including Burnet Companion which was a daytime visitor found inspecting the garden’s small patch of bird’s-foot trefoil, are well known from the local area and could reasonably be expected to turn up here sooner or later.     

Latticed Heath, 2nd August

 

Although not first-timers, other nice records during the course of 2015 of species which don’t appear here every year included Lappet Gastropacha quercifolia (2), Chevron Eulithis testata (1), Brown-tail Euproctis chrysorrhoea (1), White Satin Leucoma salicis (which bounced back with 16 individuals after last year’s complete absence), Hoary Footman Eilema caniola (1, confirmed via dissection), Kent Black Arches Meganola albula (1), Dotted Rustic Rhyacia simulans (2), Double Dart Graphiphora augur (5), Tawny Pinion Lithophane semibrunnea (4), Small Rufous Coenobia rufa (1) and Dotted Fan-foot Macrochilo cribrumalis (3).    

Lappet, 8th July

Chevron, 26th July

Brown-tail, 3rd July

Hoary Footman, 19th August

Kent Black Arches, 3rd July

 

Micros:   
 

The micro-moth species count for 2015 reached 309.  Of that total 28 were new to the site, taking the number of micros on the garden list to 463 and the overall moth total to 874.  Newcomers to the list during 2015 comprised:

 

0075	Stigmella floslactella (mine on hornbeam)	25 Oct
0113	Stigmella sakhalinella (mine on birch)	3 Nov
0152	Adela rufimitrella	27 May
0274	Bucculatrix ulmella	22 Aug
0276	Bucculatrix demaryella (mine on birch)	14 Oct
0364	Phyllonorycter geniculella (mine on sycamore)	25 Sept
0491	Coleophora gryphipennella (case on rose)	25 Oct
0501	Coleophora siccifolia *	23 June
0502	Coleophora trigeminella *	1 July
0530	Coleophora lixella *	30 June
0536	Coleophora betulella *	4 July
0642a	Metalampra italica *	10 July
0718	Ethmia dodecea	9 July
0830	Caryocolum fraternella *	9 Aug
0870	Oegoconia quadripuncta *	23 July
0880	Mompha langiella *	24 Aug
0921	Phtheochroa inopiana	1 July
0951	Aethes beatricella *	3 July
1088	Pseudosciaphila branderiana	30 June
1097	Endothenia gentianaeana  (larva inside teasel) *	31 Mar
1104	Endothenia quadrimaculana	9 Aug
1157	Crocidosema plebejana	29 Aug
1234	Pammene regiana	24 June
1272	Pammene aurana	9 Aug
1414	Synaphe punctalis	16 July
1426	Achroia grisella	16 Aug
1433	Cryptoblabes bistriga	3 June
1461	Assara terebrella *	4 July

* adult confirmed via dissection by Peter Hall

 

The record for Adela rufimitrella was of a pair found ‘in cop’ on a daisy growing in our lawn.  The tiny Cocksfoot Moth Glyphipterix simpliciella was also active here on daisies during May so provided a good reason not to mow the lawn that month!  The autumn leaf-mining season brought evidence of five species new to the garden list, including two on birch.  We have three mature birch trees but until this year little invertebrate activity has been found on them apart from saw-fly larvae, but that’s mainly because relatively few leaves are accessible without resorting to the use of a ladder – something I might try in 2016.  Four active larval cases of Coleophora gryphipennella discovered on a cultivated plant proved to be the only miners found on rosa species in the garden this year. 

Adela rufimitrella, 27th May

Coleophora gryphipennella, 25th October

 

The smart Metalampra italica is a post-millennium arrival from the Continent and seems to be working its way slowly northwards through the UK.  The sighting here on 10th July would appear to be the first record for vc24, but it is already known from Berkshire and Oxfordshire as well as counties to the east of Bucks.  This specimen was dissected because of concerns that the rather similar Metalampra cinnamomea might also find its way to the UK although it has not been recorded here yet. Despite being quite a widespread species throughout England, the gelechid Caryocolum fraternella doesn’t rate a mention in the micro-moth field guide, perhaps because it is not all that common anywhere.  There are about a dozen records for Bucks spread over quite a wide area and I’ve seen it previously at a couple of local sites so a garden record is not entirely unexpected.  Mompha langiella was not added to the Bucks list until 2013 when larval mines were found on Enchanter’s Nightshade in Burnham Beeches.  The moth is probably under-recorded.  The Westcott sighting would appear to be the county’s first light-trapped adult and around here its food-plant is more likely to be one of the various willow-herb species which it uses in addition to Enchanter’s Nightshade.

 

Metalampra italica, 10th July

Caryocolum fraternella, 9th August

Mompha langiella, 24th August

 

 

At the end of March some 20 teasel heads from plants growing alongside our property were brought indoors to be opened and 15 of them were found to contain single larvae of an Endothenia species.  Close inspection confirmed the caterpillars to be Endothenia gentianaeana due to the lack of an anal comb (rather than Endothenia marginana which also feeds on teasels and is already known from the garden), but the first adult moth to emerge on 10th June was retained and dissected by Peter Hall just to make doubly sure.  Another adult of the species came to the garden light-trap on 21st July.  Endothenia quadrimaculana, which appeared in the trap on 9th August, is a far less common species in Bucks and is in fact missing altogether from vc24 according to the distribution map which appears on the Moths Count website (link).  However, that would appear to be an oversight because there are actually five previous records for Bucks with the earliest dating back to 1993.

Endothenia gentianaeana, 31st March

Endothenia quadrimaculana, 9th August

 

Crocidosema plebejana was a nice find in the trap at the end of August, possibly a migrant but more likely dispersing inland from one of its coastal strongholds.  It is already known from some of our surrounding counties but this was a first for Bucks.  The smart pyrale Synaphe punctalis was also a first for Bucks.  It is again found mainly along coastal areas of southern England and East Anglia but there are a few records of vagrants from our surrounding counties (Bedfordshire, Hertfordshire, Berkshire & Oxfordshire) so this was presumably another moth undergoing dispersal in the warm weather.

Crocidosema plebejana, 29th August

Synaphe punctalis, 16th July

 

Migrants:

 

Finally, the table below lists the numbers of recognized migrant moth species seen at Westcott during the year, along with their first and last sighting dates. 

Plutella xylostella	5	13th June	22nd August
Udea ferrugalis	7	16th July	16th November
Nomophila noctuella	29	8th June	12th November
Vestal	2	12th September	13th September
Silver-striped Hawk-moth	1	4th July	-
Hummingbird Hawk-moth	31	6th June	7th September
Dark Sword-grass	6	6th August	6th October
Small Mottled Willow	9	3rd June	19th August
Bordered Straw	9	13th June	27th August
Small Marbled	1	3rd July	-
Ni Moth	2	9th August	29th August
Silver Y	93	3rd June	27th December

 

Silver-striped Hawk-moth, 4th July

Small Marbled, 3rd July

Ni Moth, 9th August

 

The first thing to note is that totals for some of the ‘regulars’ which appear here just about every year (the three micro-moths, Dark Sword-grass and Silver Y) were only average at best.  However, it was the appearance of the other species, some of them more than once, which helped to make 2015 so special.  There can have been few if any regular moth-trappers in Bucks who didn’t get to see Small Mottled Willow or Bordered Straw, which with Striped Hawk-moth Hyles livornica (sadly not recorded in the garden here!) invaded the UK on a massive scale.  However, the star item at Westcott has to have been the Silver-striped Hawk-moth, of which only a handful were recorded in the country.  
 

Small Mottled Willow, 3rd June 

Dark Sword-grass & Bordered Straw, 17th August