Westcott, Bucks - the year 2019 in review

While perhaps not quite as exciting as the previous year in the garden, 2019 still had its moments and there was plenty of activity from our lepidoptera.  The number of moths caught in the garden traps was certainly way up on previous years and new species kept on being found.          

Butterflies

 

2019 saw an improvement over 2018 in that more species were recorded in the garden (24 as opposed to 21) and, like a lot of other people, we had a truly remarkable number of Painted Ladies Vanessa cardui.  The first garden record here of this migrant butterfly was on 28th July and within three weeks we were regularly having counts of eight or nine at any one time on our buddleias, the peak being ten on 23rd August.    

Painted Lady, Westcott 9th August

 

The other nymphalids had an OK year, with peak counts of twelve for Red Admiral Vanessa atalanta on 23rd August, eight for Small Tortoiseshell Aglais urticae on 22nd August, nineteen for Peacock Aglais io on 1st August and three for Comma Polygonia c-album on 15th September.  Peacock numbers were actually considerably higher than in 2018 when there seemed to be few of them about and they disappeared into hibernation very quickly.

A Grizzled Skipper Pyrgus malvae on 30th May was perhaps the best butterfly sighting of all, although it has been recorded in the garden once previously back in 2011.  I look forward to Dingy Skipper Erynnis tages making a similar appearance one day because both are to be found in a field less than 100 metres from our house.  The other surprise, although again not of a first-timer, was the all-too-brief visit on 7th July of a female Silver-washed Fritillary Argynnis paphia.  Luckily I did have camera in hand for a record shot when she rested for a short while on the stump of a recently felled Portuguese Laurel.  I’ve had a handful of previous records in the garden but this was the first since 2013.   

Silver-washed Fritillary, Westcott 7th July

 

Our surviving elms produced sightings of adult White-letter Hairstreak Satyrium w-album again between 21st June and 16th July but two more of the trees have now succumbed to dutch elm disease and will need to be felled this winter.  An interesting find on 9th May was a caterpillar of this species climbing up the side of our water butt, having presumably been washed or blown off one of the nearby elms.  I kept it indoors where it continued to feed for another week before pupating. 

White-letter Hairstreak larva, Westcott 9th May

White-letter Hairstreak pupa, Westcott 18th May

 

Butterflies appearing in moth traps is not an unheard-of phenomenon and I’ve actually had 13 different species to light at night over the years although mostly away from Westcott.  However, there was a remarkable number of them in the garden during 2019, with the MV bulb bringing in a Red Admiral on 3rd August while the actinic managed Green-veined White Pieris napi (21st August), Painted Lady (21st & 25th August), Red Admiral (24th August & 5th October) and Meadow Brown Maniola jurtina (13th July). 

 

The Mothing Year

 

Two significant statistics emerged from the 2019 records at Westcott.  The first was that the list of moths recorded within the confines of the garden has now exceeded 1,000 species, all seen post-millennium and comprising almost two-thirds of the approximately 1,600 species known from Bucks.  The second was a significant increase in the number of individual moths caught in the traps here.  Those species which traditionally appear in substantial quantities anyway - moths such as Heart and Dart Agrotis exclamationis, Large Yellow Underwing Noctua pronuba, Dark Arches Apamea monoglypha and the like - did so in enormous numbers this year, most of them achieving record counts.  This gave a massive boost to the overall number of moths caught, which reached 54,400 individuals over the year for only a moderate increase in trapping effort (117 nights using the MV and actinic lights in tandem and a further 207 nights using the actinic alone, leaving 41 nights on which no trap was run).  Prior to 2019 the highest annual garden counts had been in 2015 (33,941) and 2018 (in 42,063). 

The weather wasn’t quite as spectacular during the main summer months when compared to 2018 and that seemed to have a bit of an effect on species diversity.  100 species in one night was exceeded on only 19 occasions (as opposed to 26 in 2018), the first being on 23rd June and the last on 1st August.  150 species in one night was exceeded just the once (as opposed to three times in 2018).  That best night of the year was on 23rd July 2019 when 1,217 moths of 158 species were shared between the two traps, 768 moths of 137 species coming to the MV and 449 of 97 to the actinic.  Despite the reduction in nights with very high species counts, the overall species tally for the year actually came to 699 which exceeded the previous record of 684 in 2018.  The full list of species for 2019 can be seen on a Google Sheets spreadsheet here.

 
Heart and Dart was this year’s overall winner with 4,975 individuals coming to light, although perhaps surprisingly this was only its second best garden total (6,447 visited in 2011).  It was given a good run for its money by Dark Arches which achieved the remarkable total of 3,936 on the first occasion that it has ever scored above 1,000 here.  Large Yellow Underwing (2,313), Lunar Underwing (2,312) & Setaceous Hebrew Character (2,233) were relegated to also-rans despite achieving what might have been winning scores in any other year.    Two ‘grass moth’ micro species producing almost 4,000 individuals between them was also unprecedented.  Common Wainscot, Black Rustic, Vine’s Rustic, Common Quaker and Treble Lines also put in their best ever totals here.  By co-incidence, the last spike in numbers for Treble Lines occurred in 2007 after a similarly good summer the previous year.  The top 20 species for 2019 by overall count are tabulated below:

1	Heart & Dart	4,975
2	Dark Arches	3,936
3	Large Yellow Underwing	2,313
4	Lunar Underwing	2,312
5	Setaceous Hebrew Character	2,233
6	Agriphila tristella	1,996
7	Chrysoteuchia culmella	1,925
8	Common Footman	1,032
9	Square-spot Rustic	1,011
10	Common Wainscot	963
11	Acentria ephemerella	945
12	Black Rustic	934
13	Vine’s Rustic	900
14	Common Quaker	844
15	Smoky Wainscot	683
16	Agriphila straminella	640
17	Treble Lines	635
18	Eudonia lacustrata	589
19	Scarce Footman	555
20	Patania ruralis	540

Of the aggregated species which mostly require dissection to separate, Common Rustic Mesapamea secalis, Uncertain Hoplodrina octogenaria and Rustic Hoplodrina blanda would certainly have gained a place somewhere in the top 20 if they had all been identified to species:

1	Uncertain/Rustic (Hoplodrina species)	2,884
2	Common/Lesser Common Rustic (Mesapamea species)	1,371
3	Minors (Oligia species)	373

As detailed in the table below, a further 32 moths were new to the site list during 2019 and the all-time count has now reached 1,002 (559 micros, 443 macros).  The prize for being the 1,000th moth species recorded in the garden at Westcott went to this individual:

 

Phyllonorycter klemannella, mine on alder 17th September,
adult emerged 2nd October 2019

 

4.023	Stigmella crataegella (mine on hawthorn)	11 Aug
4.062	Stigmella samiatella *	30 May
4.071	Bohemannia pulverosella (mine on apple)	17 Oct
4.088	Ectoedemia heringella *	23 Jun
10.001	Tischeria ekebladella *	24 Jun
15.082	Phyllonorycter klemannella (mine on alder)	17 Sep
17.008	Ypsolopha alpella *	27 Aug
35.116	Scrobipalpa obsoletella *	29 May
35.117	Scrobipalpa atriplicella *	21 Apr
35.149	Carpatolechia alburnella	10 July
37.009	Coleophora milvipennis *	8 July
37.077	Coleophora lassella *	29 July
38.022	Elachista gleichenella *	29 Jun
38.048	Elachista consortella *	24 Jun
38.049	Elachista stabilella *	24 Jun
49.017	Choristoneura diversana *	23 Jun
49.133	Cochylis nana	30 May
49.256	Epinotia cinereana *	26 July
49.343	Cydia amplana	25 Aug
63.017	Anania lancealis	12 July
63.109	Pediasia contaminella	29 July
52.008	Red-tipped Clearwing Synanthedon formicaeformis	22 May
70.032	Birch Mocha Cyclophora albipunctata	26 July
70.046	Oblique Carpet Orthonama vittata	25 Aug
70.155	Netted Pug Eupithecia venosata	27 May
70.276	Bordered White Bupalus piniaria	19 June
70.284	Barred Red Hylaea fasciaria	8 July
73.010	Dewick’s Plusia Macdunnoughia confusa	14 Sep
73.119	Crescent Helotropha leucostigma	3 Aug
73.139	Twin-spotted Wainscot Lenisa geminipuncta	29 July
73.221	Suspected Parastichtis suspecta	10 Jul
73.223	Oak Rustic Dryobota labecula	24 Nov

* confirmed via dissection, with grateful thanks to Peter Hall.

Micro-moths

 

There were three additions to the garden list as leaf-mines, of which Bohemmania pulverosella on apple was probably the most interesting discovery (there are only two or three previous Bucks records).  An active mine of Phyllonorycter klemannella on our alder was also a nice find and, reared indoors, the adult emerged on 2nd October.  I've also got another alder-feeding species to look out for next year:  a single vacated mine of either Stigmella alnetella or Stigmella glutinosae was found on 17th September but unfortunately the presence of a larva is required to separate those two species.  For once I remembered to search for mines of the relatively common Stigmella crataegella on hawthorn at the correct time of year and found the two illustrated below.  It is active as a larva during the summer while Stigmella oxyacanthella (whose larvae and mines look identical) is active during the autumn.   

 

Mine of Stigmella crataegella, Westcott 11th August

 

Another nice find on 8th August was a single vacated mine of Stigmella tiliae on our lime, the first here since 2013 and only the third record for Bucks.  It was also interesting to see how quickly Stigmella aceris has established itself in the garden.  This northwards-spreading species was first recorded on our Norway Maple in 2016 and a search of the accessible lower leaves on 11th August 2019 produced 33 vacated mines in no time at all, so I’m sure there will have been many more.  Rather strangely, three adult nepticulids were recorded in and around the house during the course of what turned out to be an unexpectedly warm February (very early indeed for any of these species) and they are also likely to have been Stigmella aceris although only one was confirmed via dissection.  An adult of Stigmella incognitella (19th May) also had its genitalia checked, that species having only been added to the garden list in 2018 when an active mine was found on our apple.  Adults of Stigmella samiatella (30th May) and Ectoedemia heringella (two males on 23rd June and one female on 31st July, all dissected) were unexpected because we have only one deciduous oak in the immediate vicinity and no evergreen oaks at all.  The evergreen Holm Oak Quercus ilex is an introduced Mediterranean tree species and although I’m not aware of any in Westcott there are actually a few dotted around within a radius of ten miles, mostly in churchyards and parkland or gardens.  All seem to have been “found” by Ectoedemia heringella, so these tiny moths must be very good indeed at dispersal, very much like Phyllonorycter platani (on London Plane) and Cameraria ohridella (on Horse Chestnut) which are similarly both recent invaders from continental Europe.    

Ypsolopha alpella was presumably a stray from one of the local oak woods in which I’ve seen it in the past.  Carpatolechia alburnella was a nice find because most of my records in Bucks have been from heathland sites with a good deal of birch, mainly in the south of the county.  Proving the wisdom of keeping back small, dark and obscurely marked gelechids for dissection, Scrobipalpa obsoletella and Scrobipalpa atriplicella were welcome sightings of uncommon species in Bucks.

Ypsolopha alpella, Westcott 27th Augus

Scrobipalpa atriplicella, Westcott 21st April

 

Carpatolechia alburnella, Westcott 10th July

Neither Choristoneura diversana nor Epinotia cinereana are common in Bucks and these were each the third county records.  The latter was originally considered to be a form of Epinotia nisella but is now a full species in its own right although it needs dissection to confirm.  Cochylis nana is rather more widespread in VC24 and it appeared in the garden five times between 30th May and 11th July so must now be resident somewhere quite close by.

 

Epinotia cinereana, Westcott 26th July 2019

 

Cochylis nana, Westcott 30th May

 

Cydia amplana was probably a migrant here but it does seem to be established now in some southern counties so it will be interesting to see if it appears again.  The grass moth Pediasia contaminella, with its distinctive nose-down resting posture, seemed to have a good year and turned up in other places within the county for the first time too.  It seems to be quite thinly spread and may well be under-recorded.      

 

Pediasia contaminella, Westcott 29th July

 

 

Macro-moths

 

For a further eleven macro species to be added to the site list in 2019 was nothing short of amazing.  Red-tipped Clearwing became the fifth member of this day-flying family to be tempted into the garden using pheromone lures, with single specimens appearing on two occasions (22nd May & 5th July) both to the FOR lure.  In fact it was my most successful year ever using pheromones and all of the other Clearwing species already known from Westcott turned up as well:  Red-belted Clearwing Synanthedon myopaeformis to the MYO lure (23rd & 29th June), Currant Clearwing S.tipuliformis to the TIP lure (17th & 23rd June, 5th July), Yellow-legged Clearwing S.vespiformis to the VES lure (16th July) and Orange-tailed Clearwing S.andrenaeformis also to the VES lure (22nd & 29th June, 5th July).  All came as singletons apart from Orange-tailed Clearwing, of which no less than 16 appeared on 29th June then three more on 5th July.  

 

Red-tipped Clearwing, Westcott 22nd May

 

Birch Mocha, Bordered White and Barred Red are reasonably widespread and have all been found previously in the local area so it didn’t come as a complete surprise to see them in the trap.  However, the Oblique Carpet record was the fourth for Bucks since the millennium and only the tenth ever.  It seems to be restricted to the damper areas of the clay vale and this was the first sighting since it was found on BBOWT’s River Ray Reserves during 2010.  Although seemingly in decline, Netted Pug is still fairly widespread in the southern half of the county but very rare north of the Chilterns so this was a very welcome sighting of a very smart-looking species.   

 

Oblique Carpet, Westcott 25th August

 

Netted Pug, Westcott 27th May

Dewick’s Plusia and Oak Rustic were both on my radar as species to be expected here sooner or later.  The other noctuids new to the garden list were again moths found reasonably locally, Crescent and Twin-spotted Wainscot being wetland species known from the reed-beds at nearby Calvert amongst other places, while Suspected is a birch-feeder more associated with the heathland areas of Bucks although I have found it in a couple of nearby woods on the clay.  Suspected appeared in the garden on three different occasions over the period of a week and the second example, more typically marked than the first, is illustrated below.

Crescent, Westcott 3rd August

Suspected, Westcott 14th July

Oak Rustic, Westcott 24th November

Many moths did really well in 2019 but a couple which stand out from the crowd are Mallow Larentia clavaria (32 visited in 2019, the previous highest annual total being 3 individuals) and Light Emerald Campaea margaritaria (221 recorded, more than twice the previous highest annual total).  There were only 12 sightings of Old Lady Mormo maura here, but that was double what I’ve ever had before of a species which isn’t even a guaranteed annual visitor.  In 2019 a caterpillar of the species was found in the garden for the first time.  

Old Lady caterpillar, Westcott 27th April

 Of the moths which are currently expanding their range locally, Cypress Pug Eupithecia phoeniceata (10), Oak Processionary Thaumetopoea processionea (4), Scarlet Tiger Callimorpha dominula (10), Jersey Tiger Euplagia quadripunctaria (3), Tree-lichen Beauty Cryphia algae (72), Clifden Nonpareil Catocala fraxini (2), White-point Mythimna albipuncta (119) & Kent Black Arches Meganola albula (11) appeared again as expected and all achieved their highest yet annual totals – and it was certainly a significant jump in the case of Tree-lichen Beauty and White-point.  A male Gypsy Moth Lymantria dispar also visited for the third year in a row.   

Other macro species which it was really good to see again included Narrow-bordered Five-spot Burnet Zygaena lonicerae (the first since 2005), Buttoned Snout Hypena rostralis (two appearances in the autumn, one found by torchlight on ivy blossom and the other found indoors), Garden Dart Euxoa nigricans (the first here since 2011) and two examples of Dotted Rustic Rhyacia simulans (making it six years with sightings here out of the last nine of this rather enigmatic species).
 

Narrow-bordered Five-spot Burnet, Westcott 7th July

Buttoned Snout, Westcott 25th September

 

Garden Dart, Westcott 14th July

Westcott specialities included Fox Moth Macrothylacia rubi (1 visit), Lappet Gastropacha quercifolia (4 visits), Garden Tiger Arctia caja (2 visits) & Double Dart Graphiphora augur (1 visit).  A final-instar Fox Moth caterpillar was also found walking across the lawn towards the light trap in October, quite possibly the progeny of the adult female which visited on 24th May.    

 

Fox Moth caterpillar, Westcott 10th October

 

As in most years there were a few unexpected absentees but in 2019 they were species which only ever appear here in small numbers at best.  In 2019 they included Small Rivulet Perizoma alchemillata, Poplar Kitten Furcula bifida (whereas close relative Sallow Kitten Furcula furcula had its best ever year), Pale-shouldered Brocade Lacanobia thalassina, Cabbage Moth Mamestra brassicae and Ingrailed Clay Diarsia mendica.

 

Migrant Moths

 

It was a reasonable year for migrants at Westcott and they are tabulated below with first and last noted dates.  As mentioned earlier, Cydia amplana was a first timer for the garden, otherwise the most interesting visitors were Pearly Underwing Peridroma saucia and Delicate Mythimna vitellina (last noted here in 2006 and 2013 respectively).

 

Plutella xylostella	191	10th June	24th Nov
Cydia amplana	1	25th August	-
Udea ferrugalis	25	29th July	26th Nov
Nomophila noctuella	5	5th July	3rd Oct
Hummingbird Hawk-moth	26	3rd July	12th Oct
Vestal	1	3rd October	-
Dark Spectacle	1	23rd Sep	-
Silver Y	83	7th January	25th Nov
Bordered Straw	1	4th July	-
Scarce Bordered Straw	2	25th Sep	30th Sep
Pearly Underwing	1	23rd Oct	-
Delicate	1	30th July	-
Dark Sword-grass	6	6th April	29th Sep

 

Cydia amplana, Westcott 25th August

 

Pearly Underwing, Westcott 23rd October

 

Delicate, Westcott 30th July