To put
the site into context, these results come from an untidy rural village garden in
grid square SP7117 out on the heavy clay of Aylesbury Vale. Native trees and shrubs within and around the
edge of the garden include virtually all of the common species which are to be
found growing wild in the local area, apart from oak. Adjacent to us are other mature gardens, a churchyard
and sports field as well as farmland (mostly grazing pasture). There are several ponds nearby and a decent
network of ditches along with plenty of ancient hedgerows, a few of which are hacked
to death annually but many others are left nicely unkempt. The closest parts of the former Westcott
airfield, now an industrial park, are turning into secondary woodland and much
of the site’s boundary fence is lined with mature poplars. On the far side of the airfield is a disused
railway cutting with its own unique habitat although this is slowly being lost
to scrub. A mile to the east can be
found the manicured grounds of Waddesdon Manor, while a mile to the north-west
there is mixed deciduous plantation woodland covering an old landfill
site. A small amount of mature oak
woodland lies a mile to the south but there is much more of it within a radius
of five miles. Bernwood Forest is seven
miles away as the crow flies and the scarp slope of the Chiltern Hills is just
under ten miles away at its closest point.
Butterflies
While 2018
was reasonable for butterflies in the garden, it wasn’t a vintage year. 21 species were recorded, the first being a
Small Tortoiseshell Aglais urticae tempted
out of hibernation on 17th February and the last a Red Admiral Vanessa atalanta visiting ivy blossom on
21st October. The only obvious absentees
were Small Skipper Thymelicus sylvestris
and Essex Skipper Thymelicus lineola
and in fact one or other did visit briefly on 15th July but I wasn’t quick
enough to identify it properly. Small
Heath Coenonympha pamphilus appeared again
after an absence of five years, a single second-brood specimen visiting our
cat-mint on 9th September. Although quite
widespread in the local countryside, the species rarely finds its way into the
garden.
 |
| Small Heath, Westcott 9th September 2018 |
Star of the show once again was White-letter Hairstreak Satyrium w-album which was recorded regularly on our surviving garden elms over a four-week period between 23rd June and 19th July. Unusually, on 10th July I had camera in hand when a female landed on the lawn and went walk-about for a few minutes. It was not immediately clear what she was searching for!
 |
| White-letter Hairstreak, Westcott 10th July 2018 |
At least one female Brown Hairstreak Thecla betulae must have come very close once again because on 5th October an egg was found on blackthorn less than 50 metres away in a hedge surrounding the adjacent churchyard, but it is four years now since the last sighting of an adult actually within the garden.
The
buddleias didn’t attract many vanessids during the summer and neither did our ivy
blossom later in the year. While it was good
to see singletons of the migrant Painted Lady Vanessa cardui on half a dozen occasions between July and
September, the resident Red Admirals achieved a high of only six individuals at
any one time, Peacock Aglais io a
maximum of two (present only over three consecutive weeks in July), Small
Tortoiseshell just four and Comma Polygonia
c-album a maximum of three at once.
Those are very disappointing numbers.
Other common summer species such as Meadow Brown Maniola jurtina and Gatekeeper Pyronia
tithonus were around in lower numbers than usual and seemed to finish quite
quickly, the one exception being Speckled Wood Pararge aegeria which for a change was recorded here regularly in
every month between April and September.
The Mothing Year
2017
might have been a fantastic year for moths at Westcott but 2018 proved to
be an even better one! The overall catch
amounted to just over 42,000 individuals, which is half as many again as the
previous year and significantly more than the previous record of 33,941 in
2015. The twin-30wt actinic trap was deployed
in the garden on every suitable night that I was here (295 in all, roughly comparable
to previous years). Most of the missing nights
were due to harsh winter conditions between early January and the end of March
and then holiday absences in May and September.
The difference in 2018 was the number of occasions on which the 125wt Mercury
Vapour trap was run in addition to the actinic (87 nights, as opposed to 32 in
2017). Using the two different types of
light in tandem certainly paid dividends, particularly during the busiest
months of June and July, even though they were placed only ten metres apart (separated
from each other by a fairly thick hedge).
100 species in one night was exceeded on 26 occasions during those two
months and 150 species was exceeded three times, the best catch of the year
being on 4th July when 165 different species turned up to the two lights (660
individual moths of 126 species to the MV, 353 of 93 species to the actinic).
Top 20 Highest Counts, 2018
| ||
| 1 | Setaceous Hebrew Character | 1819 |
| 2 | Acentria ephemerella | 1798 |
| 3 | Heart and Dart | 1571 |
| 4 | Large Yellow Underwing | 1366 |
| 5 | Lunar Underwing | 1190 |
| 6 | Common Footman | 1126 |
| 7 | Square-spot Rustic | 1077 |
| 8 | Flame Shoulder | 1060 |
| 9 | Patania (Pleuroptya) ruralis | 975 |
| 10 | Smoky Wainscot | 874 |
| 11 | Yponomeuta evonymella | 856 |
| 12 | Dark Arches | 789 |
| 13 | Agriphila straminella | 722 |
| 14 | Straw Dot | 719 |
| 15 | Agriphila tristella | 694 |
| 16 | Brimstone Moth | 684 |
| 17 | Vine's Rustic | 639 |
| 18 | Beaded Chestnut | 496 |
| 19 | Chrysoteuchia culmella | 462 |
| 20 | Black Rustic | 421 |
For a change it was Setaceous Hebrew Character Xestia c-nigrum which topped the leader board with 1,819 individuals caught between 20th May and 6th November. As expected, Heart and Dart Agrotis exclamationis (1,571) and Large Yellow Underwing Noctua pronuba (1,366) also performed well but they were unexpectedly relegated to third and fourth place behind the aquatic micro-moth Acentria ephemerella (1,798) which came second. A further five micros achieved a spot in the top 20, including Mother of Pearl Patania (Pleuroptya) ruralis which at 975 only just failed to break the thousand barrier and Bird-cherry Ermine Yponomeuta evonymella which did exceptionally well to reach 856.
Of the
aggregate species shown below, Common Rustic Mesapamea secalis, Uncertain Hoplodrina
alsines and Rustic Hoplodrina blanda
would certainly have gained a place somewhere in the top 20 if they had all
been identified to species.
Aggregate Counts, 2018
| ||
| 1 | Oligia species (Minors) | 439 |
| 2 | Hoplodrina species (Uncertain & Rustic) | 1313 |
| 3 | Mesapamea species (Common/Lesser Common Rustic) | 1476 |
As far as
individual moth species are concerned the total achieved over the year came to 685
(345 micros and 340 macros - the full species list can be viewed here), better even than the 662 recorded in 2017 and must
be just about on the limit of what is possible here in a single year. The all-time garden lepidoptera list,
accumulated post-millennium, now stands at 1002 species (971 moths, 31
butterflies) with the following 35 new additions for 2018:
4.053
|
Stigmella incognitella (mine on Apple)
|
20 Oct
|
4.058
|
Stigmella basiguttella *
|
2 Aug
|
4.078
|
Ectoedemia septembrella *
|
9 July
|
4.090
|
Ectoedemia subbimaculella *
|
11 June
|
16.022
|
Cedestis subfasciella *
|
1 July
|
32.021
|
Agonopterix assimilella *
|
22 Aug
|
35.019
|
Anarsia innoxiella *
|
3 July
|
35.101
|
Gelechia sororculella *
|
21 June
|
37.036
|
Coleophora conyzae *
|
4 July
|
37.104
|
Coleophora adspersella *
|
1 July
|
38.025
|
Elachista atricomella *
|
21 July
|
45.011
|
Amblyptilia punctidactyla *
|
23 June
|
45.028
|
Capperia britanniodactylus *
|
28 June
|
49.014
|
Archips crataegana *
|
17 June
|
49.087
|
Acleris literana
|
11 Mar
|
49.108
|
Gynnidomorpha alismana *
|
14 July
|
49.162
|
Celypha rosaceana *
|
3 July
|
49.195
|
Bactra furfurana *
|
19 July
|
49.318
|
Dichrorampha vancouverana *
|
23 July
|
49.347
|
Grapholita compositella
|
21 July
|
49.356
|
Grapholita lobarzewskii *
|
11 June
|
49.358
|
Grapholita tenebrosana *
|
26 June
|
62.053
|
Ancylosis oblitella *
|
4 Aug
|
63.047
|
Spoladea recurvalis
|
15 Oct
|
63.118
|
Nymphula nitidulata *
|
6 July
|
63.120
|
Chilo phragmitella *
|
4 July
|
70.174
|
Pinion-spotted Pug Eupithecia insigniata *
|
7 May
|
71.001
|
Oak Processionary Thaumetopoea processionea
|
19 July
|
72.030
|
Jersey Tiger Euplagia quadripunctaria
|
31 July
|
72.041
|
Four-spotted Footman Lithosia quadra
|
14 July
|
73.072
|
Marbled Clover Heliothis viriplaca
|
26 July
|
73.137
|
Fen Wainscot Arenostola phragmitidis
|
4 July
|
73.302
|
Obscure Wainscot Leucania obsoleta
|
25 Jun
|
73.332
|
Purple Clay Diarsia brunnea
|
13 Jun
|
74.011
|
Cream-bordered Green Pea Earias clorana
|
9 July
|
* confirmed via dissection, with grateful thanks to Peter Hall.
Micro-moths
Not a lot
of effort was put into searching for leaf-mines during 2018 and only 30
different species were recorded in the garden at that stage of their life
cycle. Just the one was new, a single
mine of Stigmella incognitella found on our domestic apple during October. Considering how widespread its food-plant is,
especially in gardens, this seems to be a genuinely uncommon moth in
Bucks. In the photo below the fully-grown
larva (orange-yellow body, brown head) can be seen feeding in the central
blotch. Ignore the thinner corridor mine
with broken frass running from bottom to top on the left side as that is the
ubiquitous Lyonetia clerkella mining
the same leaf.
 |
| Mine of Stigmella incognitella, Westcott 20th October 2018 |
On the
other hand, an adult Stigmella
basiguttella in the garden was a big surprise because, despite being a
relatively common species, oak is in short supply locally and I can’t imagine
such a tiny moth flying all that far from its foodplant.
The two Coleophorids take the number of species from that family recorded in the garden to 41, all confirmed by dissection. Coleophora conyzae (whose larvae feed on Hemp-agrimony, Ploughman’s-spikenard and Common Fleabane) is only the second record for Bucks. Until 2018 there were only four county records of Agonopterix assimilella, all from the greensand ridge on the Bedfordshire border where the larval foodplant Broom is fairly widespread. The moth is probably under-recorded in the county because I had it in some numbers in Rowley Wood near Black Park during 2018, where there is also a large amount of Broom, but the plant isn’t at all common on the clay so the garden sighting at Westcott will probably have been associated with cultivated varieties. The Gelechid Anarsia innoxiella seems to be a species on the move because in 2018 I had three individuals in the garden between 3rd and 8th July. It is a fairly recent split from the pest species Peach Twig Borer Anarsia lineatella. Adding two more Plume species to the garden list was also very pleasing. Capperia britanniodactylus is uncommon in Bucks with only five previous records, four from Burnham Beeches and the other from Stoke Common. Its larval foodplant is Wood Sage, for which the on-line BSBI distribution maps show no records at all for my 10km square SP71, but this perennial is widespread throughout the UK and is sometimes grown in gardens. The other moth, Amblyptilia punctidactyla, doesn’t come as a surprise because its larvae feed on Hedge Woundwort of which we have plenty in the garden.
 |
| Capperia britanniodactylus, Westcott 28th June 2018 |
The
tortricoid moths Gynnidomorpha alismana,
Celypha rosaceana, Bactra furfurana & Grapholita compositella have been
recorded previously in this general area (C.
rosaceana closest of all, from the disused railway cutting west of
Westcott) so they’re not unexpected in the garden. However, the other two Grapholita species, lobarzewskii
and tenebrosana, are both rare in
Bucks with only three previous county records for each of them, while Dichrorampha vancouverana is supposedly
a widespread moth but in VC24 there have been only two previous sightings, both
in the same lay-by on the A41 east of Aston Clinton, right on the
border with Herts. Ancylosis oblitella is a migrant which became established in
south-east England in the 1950s and has been slowly spreading northwards. There is one previous Bucks record (in 2003 from
Milton Keynes) but it looks as though the moth may now be here to stay as four
were trapped in the garden during August 2018.
Beautiful China-mark Nymphula
nitidulata is the least common of the China-mark moths and finally “completes
the set” for the garden, two being recorded on 6th July and a third following
on 22nd August.
 |
| Gynnidomorpha alismana, Westcott 14th July 2018 |
 |
| Grapholita compositella, Westcott 21st July 2018 |
 |
| Grapholita lobarzewskii, Westcott 11th June 2018 |
 |
| Ancylosis oblitella, Westcott 4th August 2018 |
Of the
micros which weren’t first timers it was particularly good to see Eana incanana once again (26th June),
the first garden example for ten years of this moth which is associated with
bluebells. In addition, Sorhagenia rhamniella (1st July) and Epinotia nanana (11th June & 7th
July) have each been recorded here only once previously.
Macro-moths
To get nine
new macro-moth species was unexpected, especially having had the exact same
number of new ones in 2017. The garden
macro list now stands at 432 and you would have thought that, by now, getting
new ones would be a rare event. However,
the Bucks all-time macro-moth list is hovering around the 630 mark (albeit
including some 60 or so which haven’t been recorded since the millennium and
may well now be extinct in the county), so there is certainly still the
potential for further species to turn up.
In particular there are a number of moths known to be on the move in our
region which hopefully might reach the garden within a few years, Dewick’s
Plusia Macdunnoughia confusa,
Toadflax Brocade Calophasia lunula,
Black-spotted Chestnut Conistra
rubiginosa, Oak Rustic Dryobota
labecula, Clancy’s Rustic Caradrina
kadenii and L-album Wainscot Mythimna
l-album to name but a few.
The nationally
scarce Pinion-spotted Pug visited twice, the second example coming to light on
21st May and that is the one illustrated below because the first wasn’t in
pristine condition. There are 20
previous sightings for Bucks, many from the area around Milton Keynes, but only
seven are post-millennium and those at Westcott are the first records since
2010 which seems to fit with the literature in that the moth is “seldom
seen”. Males of the potential pest
species Oak Processionary appeared in the trap three times over the period of a
week in July and I’m sure the moth must now be here to stay no matter how hard
the Forestry Commission is trying to eradicate it.
 |
| Pinion-striped Pug, Westcott 21st May 2018 |
 |
| Oak Processionary, Westcott 19th July 2018 |
The smart
Jersey Tiger was of the form lutescens
with yellow rather than red hind-wings and was expected at Westcott sooner or
later. However, Marbled Clover (a first
for Bucks) certainly wasn’t expected and it is unclear where that moth will
have come from. A Red Data Book species
resident mainly in the breckland area of East Anglia, it is also known to have
strong migratory tendencies.
 |
| Jersey Tiger f. lutescens, Westcott 31st July 2018 |
 |
| Marbled Clover, Westcott 14th July 2018 |
Garden
Tiger Arctia caja put in five
appearances, the third year in a row that this fast declining but formerly
widespread species has graced the trap, so there must still be a small residual
population locally. Red-necked Footman Atolmis rubricollis made only its second
appearance after the first in 2013, while Clifden Nonpareil Catocala fraxini visited once again
after joining the garden list in 2017. Gold
Spot Plusia festucae had a fantastic
season with 88 of them recorded in the garden between 10th June and 10th
October. I’ve never before had a double-digit
annual count nor seen any daytime activity from the species.
 |
| Gold Spot, Westcott 4th August 2018 |
A single Bordered Sallow Pyrrhia umbra was trapped on 29th June, making its first visit to the garden since 2007. Rosy Minor Litoligia literosa, presumably a stray from the Chilterns, put in another appearance on 4th August, the first to be seen here for five years. The elm-feeding Lesser-spotted Pinion Cosmia affinis was first recorded in the garden during 2016 but sadly none appeared the following year. However, in 2018 I had no less than ten of them between 12th July and 5th August, so hopefully it has re-established itself locally. Finally, on 15th September I was pleased to find Large Ranunculus Polymixis flavicincta in the trap once again, the first garden record since 2011.
Finding
moths that didn’t do well in 2018 has been a challenge. There were just two unexpected absentees from
the traps, Nutmeg Anarta trifolii and
Shears Hada plebeja. They are two closely-related species which can
normally be relied upon to make a handful of visits each year. Both are double-brooded locally which makes
their complete absence even more surprising.
Common Swift Korscheltellus
lupulina had a relatively poor season and I was disappointed not to see Dotted
Fan-foot Macrochilo cribrumalis after
a run of five consecutive years of garden records.
During the second half of 2018 some noticeably smaller-than-usual moths began to appear in the trap, illustrated well by the normal and pint-sized Lime-speck Pugs in the picture below. In some cases this may well have been caused by the dessication of their food-plant materiel during the very hot summer, resulting in larvae being forced to attempt pupation before they would normally have done so.
During the second half of 2018 some noticeably smaller-than-usual moths began to appear in the trap, illustrated well by the normal and pint-sized Lime-speck Pugs in the picture below. In some cases this may well have been caused by the dessication of their food-plant materiel during the very hot summer, resulting in larvae being forced to attempt pupation before they would normally have done so.
 |
| Lime-speck Pugs, Westcott 23rd July 2018 |
Migrant Moths
It was a reasonable year for migrants at Westcott and two or three notable species did visit the garden, although the usually common Rusty-dot Pearl Udea ferrugalis and Rush Veneer Nomophila noctuella made only a single visit each. Pride of place must go to the smart Crambid Spoladea recurvalis on 15th October which was not only a first timer here but was also a first for Bucks. It is not a common migrant, rarely getting beyond the coast, but in October 2018 many examples were seen inland and they included first county records for Beds and Herts as well as Bucks. Four-spotted Footman was another first-time visitor to the garden, while Palpita vitrealis was the second of that species to appear after one the previous year. Dark Sword-grass Agrotis ipsilon had its best year ever here (and produced my first December records of the species) but one wonders if some may actually have been home-grown individuals rather than migrants. The same is true of Dark Spectacle Abrostola triplasia which is appearing more often in the county nowadays and may be in the process of becoming established. On the other hand, the resident Turnip Moth Agrotis segetum did unexpectedly well with 117 individuals recorded in the garden between May and November (38 was the previous highest annual count here). During 2018 its numbers will almost certainly have been boosted by immigration, especially during the autumn.
It was a reasonable year for migrants at Westcott and two or three notable species did visit the garden, although the usually common Rusty-dot Pearl Udea ferrugalis and Rush Veneer Nomophila noctuella made only a single visit each. Pride of place must go to the smart Crambid Spoladea recurvalis on 15th October which was not only a first timer here but was also a first for Bucks. It is not a common migrant, rarely getting beyond the coast, but in October 2018 many examples were seen inland and they included first county records for Beds and Herts as well as Bucks. Four-spotted Footman was another first-time visitor to the garden, while Palpita vitrealis was the second of that species to appear after one the previous year. Dark Sword-grass Agrotis ipsilon had its best year ever here (and produced my first December records of the species) but one wonders if some may actually have been home-grown individuals rather than migrants. The same is true of Dark Spectacle Abrostola triplasia which is appearing more often in the county nowadays and may be in the process of becoming established. On the other hand, the resident Turnip Moth Agrotis segetum did unexpectedly well with 117 individuals recorded in the garden between May and November (38 was the previous highest annual count here). During 2018 its numbers will almost certainly have been boosted by immigration, especially during the autumn.
 |
| Spoladea recurvalis, Westcott 15th October 2018 |
 |
| Four-spotted Footman, Westcott 14th July 2018 |
One thing
of particular note in 2018 was the record number of visits from the enchanting
Hummingbird Hawk-moth Macroglossum
stellatarum which had its best ever year here. There were many occasions when two appeared
at the same time on the buddleia outside our kitchen window and three were seen
together there on three separate dates in August. It was one species which the rest of the
family showed some interest in and those extra pairs of eyes certainly helped
the records to accumulate. Silver Y Autographa gamma also did well during
the year but didn’t beat the totals achieved here in 2006 or 2013. To conclude, the table below gives totals along with first and last sighting dates for the migrants recorded at Westcott in 2018:
Plutella xylostella
|
48
|
25th
May
|
21st
Dec
|
Udea ferrugalis
|
1
|
15th
Nov
|
-
|
Spoladea recurvalis
|
1
|
15th
Oct
|
-
|
Palpita vitrealis
|
1
|
12th
Oct
|
-
|
Nomophila noctuella
|
1
|
7th
Aug
|
-
|
Vestal
|
2
|
13th
Oct
|
16th
Oct
|
Hummingbird
Hawk-moth
|
75
|
11th
Jul
|
29th
Sep
|
Four-spotted
Footman
|
1
|
14th
Jul
|
-
|
Dark
Sword-grass
|
29
|
9th
Jul
|
6th
Dec
|
Scarce
Bordered Straw
|
1
|
13th
Aug
|
-
|
Silver Y
|
226
|
24th
May
|
22nd
Dec
|
Dark
Spectacle
|
3
|
4th
July
|
20th
July
|
