The Marsh Gibbon RIS Trap

The Rothamsted Insect Survey celebrated its 50th anniversary in 2014.  This nationwide system of light traps was established in the early 1960s in an attempt to better understand moth population changes.  Further information on the origins and development of the survey can be found in an article by Ian Woiwod et al here and in another article on the Biotechnology & Biological Sciences Research Council website here. 

 

Rothamsted light traps are identical fixed traps which use a 200wt clear tungsten bulb.  The nightly catch falls into a collecting jar laced with Tetrachloroethylene which kills the insects.  For consistency, even in these more conservation–conscious days, it is necessary to continue the collection of dead insects using the same type of bulb in order to make sense of the invaluable data provided, but in defence of the network it should be pointed out that the tungsten bulbs pull in samples which are far smaller than the MV or actinic light traps used by enthusiasts today.   

 

The national network currently consists of some 80 or so traps.  Changes in circumstances have meant that few of those running today have been in operation since the very start of the survey.  In Bucks the first trap began operation in Chesham during 1968 but only lasted until the following year.  The 1970s saw several traps set up in the north of the county during the development of Milton Keynes, one in Howe Park Wood providing more than 15,000 records over eight years, but they had all been closed down by the end of that decade.  A light was run at Chalfont St Giles from 1981 until 1985 but thereafter there were no more RIS traps in the county until 2001 when the Burnham Beeches example began collecting data.  It was joined by the trap at Marsh Gibbon in 2006 and these two are still running today.

Location:	Trap:	Grid reference:	Period:
Bletchley Park	144	SP 863337	1970-1974
Bletchley	150	SP 866336	1971-1972
Bradwell Abbey	354	SP 827395	1977-1978
Burnham Beeches	588	SU 945845	2001-current
Chalfont St Giles	435	SU 986935	1981-1985
Chesham	110	SU 960020	1968-1969
Howe Park Wood	170	SP 831342	1970-1977
Marsh Gibbon	629	SP 647210	2006-current
Shenley Brook End I	145	SP 835355	1969-1974
Shenley Brook End II	297	SP 837355	1974
Simpson I	147	SP 878367	1970-1972
Simpson II	155	SP 878366	1975
Stony Stratford	143	SP 792405	1970

Located on the clay of the Vale of Aylesbury in the north-west of the county, trap 629 is sited on a field margin adjacent to a tall mixed hedgerow on a working farm to the south of Marsh Gibbon.  In contrast to the Burnham Beeches trap the habitat at Marsh Gibbon is unremarkable and the species list had reached only 255 moths by the end of 2012 (251 macros but just 4 micros).  The Rothamsted survey concentrates only on the macro-moth species but, co-incident with me taking over identification of each nightly catch during 2013, a greater effort has now been made to sort through the ‘by-catch’ and the list now stands at 430 moth species (263 macros and 167 micros). 

  

 

Although most of the species on the list are common and widespread, the site has produced one or two nice moths.  Garden Tiger Arctia caja still puts in occasional appearances, averaging a sighting every other year which makes this one of the most consistent sites in Bucks for a rapidly-declining species.  Lappet Gastropacha quercifolia and Double Dart Graphiphora augur also turn up regularly.  Twin-spotted Wainscot Archanara geminipuncta and Brown-veined Wainscot Archanara dissoluta have each visited the trap but this is quite a low-lying area and there are plenty of reeds in the roadside ditches south of the farm down towards the River Ray.  The most pleasing finds in 2014 were Cream-bordered Green Pea Earias clorana on 22nd July and Oak Eggar Lasiocampa quercus on 26th July, neither of which had been previously recorded at the site.  No exceptional micro-moths have yet been discovered but at least the list of species is now making decent progress.

 

Cream-bordered Green Pea

 

 

 

Moth surveying in Bernwood Forest, 2009 - 2014

The macro-moths of Aylesbury Vale’s largest tract of woodland, Bernwood Forest, have been reasonably well documented over the years, thanks in part to the site’s closeness to the educational establishments in Oxford.  Indeed, Bernwood and Burnham Beeches are probably the two best recorded moth sites in Buckinghamshire.  However, those individuals who ran light traps in Bernwood regularly over previous decades (including some quite famous names) seem to have ignored the smaller species.  Until 2009 the list of micro-moths known from within each of the main forest compartments was fewer than 100 (and significantly fewer than that for some of them).  It was this dismal coverage of micros which prompted Peter Hall and I to seek permission to visit Bernwood on a regular basis from 2009 onwards and we have the Forestry Commission to thank for allowing us access.

Back in the time of Edward the Confessor, Bernwood was a Royal hunting forest and covered much of present-day north-western Bucks.  By the 16th Century it had lost its Royal status, having been reduced in size significantly through deforestation and by parcels of it being given away by the Monarch to others in return for favours.  What we now know as Bernwood Forest is the largest remaining relict, but at 305 hectares is only a very small portion indeed of the original Royal hunting forest.

 

All of present-day Bernwood Forest has Site of Special Scientific Interest (SSSI) status.  The majority of it lies in Bucks where it is known by Natural England as the ‘Shabbington Woods Complex’.  The forested areas comprise Oakley Wood, York’s Wood, Shabbington Wood and Hell Coppice.  Adjacent to the west are Bernwood Meadows, two Wildlife Trust-owned ridge and furrow meadows which are also included within the SSSI.  Adjacent to the east lies the M40 Compensation Area, an area of grassland and scrub designed for the Black Hairstreak butterfly which is owned by the Highways Agency.  To the south, on the Oxfordshire side of the county boundary, is Waterperry Wood.  All of the woodland areas are owned by the Forestry Commission and were designated as a Forest Nature Reserve in 1981, mainly for their butterfly and moth interest.  Unfortunately, like many similar sites in England, much of the interior had been given over to conifers during the 1950s and 1960s although a few compartments were replanted with oak.  Aerial spraying was employed up until the late-1960s, including the use of DDT to control pine weevil.  However, against the odds, many broadleaved trees and shrubs from the original ancient woodland still survive along the ride margins of each compartment and the conifers are now gradually being removed.

Between 2009 and 2014 the site received 110 survey visits with between two and four 125w Mercury Vapour light-traps run each time, so an average of 18 visits per annum.  There were no overnight sessions, the trapping being carried out from dusk for up to four hours.  The catch from each trap was then identified and released.  Most of the visits took place between April and September although in some years, when the weather was suitable, there were additional sessions earlier in the spring as well as through the autumn into December.  All of the main areas of woodland were worked quite thoroughly apart from Waterperry Wood (Oxon) which only received attention on a couple of occasions and even then only from a 15w battery-powered actinic trap.  Each of the trap sites employed is indicated by a red ‘x’ on the map below:

 

In the first two years of trapping in Bernwood Forest we recorded 520 species, just over half of them (267) being micro-moths.  By the end of 2014 that total had risen to 734 (of which 404 were micro-moth species).  There are historic records of a further 116 (5 micro and 111 macro species) which were not recorded during the survey.  Some of them may still be waiting to be found but, because the majority haven’t been seen since the 1960s, the chances are that most are no longer present. 
 

The two most significant micro-moth discoveries were both species new to the United Kingdom.  The nepticulid Ectoedemia longicaudella (Klimesch, 1953) was first found on 12th July 2009 in Shabbington Wood and has subsequently been recorded from other areas of the forest.  Its larval stage mines the bark of young oak trees in similar fashion to Ectoedemia atrifrontella and the adults of these two species are in fact indistinguishable without examination of their genitalia.  As luck would have it, both species were confirmed in Bernwood during 2010.  The tortricoid moth Cydia indivisa (Danilevsky, 1963) was trapped on 4th June 2010 in Oakley Wood.  The single example that was found came to an MV light placed along the boundary between two forest compartments (one of oak, the other of spruce), both of which were planted in 1965.  The moth’s larvae feed under the bark of Norway Spruce so it could have been present unnoticed in Bernwood for over 40 years.  However, the spruce compartment has subsequently undergone significant thinning and, despite attempts in the same area over several years, the species has not been re-found.

Listed below are the more significant micro-moth finds at Bernwood.  Most are nationally scarce while others are uncommon at the county level.  Some of them are simply a result of under-recording in the county and have subsequently been found elsewhere in appropriate habitat (for example Ectoedemia angulifasciella, Phtheochroa inopiana, Gypsonoma oppressana and Pammene giganteana), while others are actually quite rare (for example Grapholita lobarzewskii and Cydia illutana):
 

2	Micropterix mansuetella	18th May 2012	Nb, 2nd record for VC 24
28	Ectoedemia angulifasciella	7th Jul 2010	4th record for VC 24
37	Ectoedemia albifasciella	4th Jun 2010	4th record for VC 24
41	Ectoedemia atrifrontella	16th Aug 2010	1st record for VC 24
41b	Ectoedemia longicaudella	12th Jul 2009	1st record for UK
86	Stigmella roborella	16th Aug 2010	2nd record for VC 24
113	Stigmella sakhalinella	4th Jun 2010	3rd record for VC 24
135	Lampronia luzella	21st Jun 2013	Nb, 2nd record for VC 24
335	Phyllonorycter salicicolella	16th Aug 2010	4th record for VC 24
336	Phyllonorycter dubitella	23rd Apr 2011	Nb, 2nd record for VC 24
403	Argyresthia glabratella	17th Jun 2010	Nb, 2nd record for VC 24
494a	Coleophora prunifoliae	9th Jul 2013	Nb
501	Coleophora siccifolia	28th Jun 2013	Nb, 3rd record for VC 24
511	Coleophora orbitella	23rd Jun 2010	Nb, 2nd record for VC 24
620	Elachista gangabella	17th Jun 2010	2nd record for VC 24
622	Elachista adscitella	16th Aug 2010	Nb
625	Biselachista cinereopunctella	1st Jun 2011	Nb, 2nd record for VC 24
633	Cosmiotes stabilella	17th Jun 2014	Nb (in Waterperry Wood)
661	Pseudatemelia flavifrontella	15th Jun 2011	Nb, 3rd record for VC 24
718	Ethmia dodecea	7th Jul 2010	1st record for VC 24
755	Stenolechia gemmella	24th Aug 2010	3rd record for VC 24
764	Pseudotelphusa scalella	4th June 2010	Nb
806	Gelechia nigra	11th Jul 2010	Na, 2nd record for VC 24
879	Batrachedra pinicolella	7th Jul 2010	Nb
921	Phtheochroa inopiana	11th Jul 2010	4th record for VC 24
952	Commophila aeneana	30th May 2012	Nb (in M40 Comp. Area)
982	Choristoneura diversana	17th Jun 2014	Na (in Waterperry Wood)
1088	Pseudosciaphila branderiana	22nd Jun 2009	Nb
1121	Ancylis upupana	4th Jun 2010	Nb, 2nd record for VC 24
1125	Ancylis unculana	22nd May 2009	Nb
1143	Epinotia fraternana	17th Jun 2010	Nb, 1st record for VC 24
1145	Epinotia nanana	15th Jun 2011	Nb
1152	Epinotia maculana	3rd Oct 2011	Nb
1170	Gypsonoma oppressana	23rd Jun 2010	Nb,
1180	Epiblema tetragonana	3rd Jun 2014	Na, 2nd record for VC 24
1217	Eucosmomorpha albersana	4th Jun 2010	3rd record for VC 24
1227	Pammene giganteana	6th Apr 2010	Nb, 1st record for VC 24
1249	Grapholita lobarzewskii	1st Jul 2011	Na, 1st record for VC 24
1266a	Cydia illutana	1st Jun 2011	RDB, 2nd record for VC 24
1266b	Cydia indivisa	4th Jun 2010	1st record for UK

 

The status codes in the right-hand column are explained as follows:

Nb = Nationally Scarce ‘B’ List (known from 31-100 10km squares in the UK)

Na = Nationally Scarce ‘A’ List (known from 16-30 10km squares)
RDB = Red Data Book species (known from 15 or fewer 10km squares)

Micropterix mansuetella

Lampronia luzella

Grapholita lobarzewskii

Cydia indivisa

 

Moving on to the larger moths, the following macros were of significant interest:

174	Triangle	Heterogenea asella	7th July 2010	RDB
1678	Blair’s Mocha	Cyclophora puppillaria	4th Oct 2011	Migrant
1751	Devon Carpet	Lampropteryx otregiata	17th Aug 2009	Nb
1821	Valerian Pug	Eupithecia valerianata	1st July 2010	Nb
1822	Marsh Pug	Eupithecia pygmaeata	20th May 2011	Nb
2039	Red-necked Footman	Atolmis rubricollis	28th June 2013
2067	Jersey Tiger	Euplagia quadripunctaria	29th Aug 2013
2075	Small Black Arches	Meganola strigula	7th July 2010	Na
2191	Double Line	Mythimna turca	7th July 2010	Nb, Migrant
2488	Common Fan-foot	Pechipogo strigilata	20th May 2009	Na

Triangle

Common Fan-foot

The Red Data Book species Triangle was seen three times during 2010, twice in Oakley Wood (7th July and 20th July) and once in Hell Coppice (20th July).  There is only one previous record of the moth in Bucks, dating from 1956, so this must go down as one of the most important finds to date during the survey.  The moth is associated with oak and is believed to be a canopy dweller, making it difficult to record.  Devon Carpet is a species that is spreading from the south-west.  The individual trapped in Shabbington Wood on 17th August 2009 was the second record for Bucks (the first having been caught in the grounds of Waddesdon Manor four days earlier).  The species is presumably now resident in Bernwood because another was found on 15th August 2013, this time in Oakley Wood.  The record of Valerian Pug was only the third for Bucks and it was found again at the same site in Oakley Wood in 2011 and in Hell Coppice in 2013, while the record of Marsh Pug was actually a day-time find in Bernwood Meadows.  Red-necked Footman and Jersey Tiger are two moths currently expanding their range northwards.

Small Black Arches seems to be well established throughout the forest and was recorded again in 2011, 2013 & 2014, the highest count achieved being six individuals in Oakley Wood on 18th July 2013.  Common Fan-foot was already well known from Bernwood, the first Bucks database record dating back to 1940 in Shabbington Wood by A. Maitland Emmet.  It was recorded each year during the survey from most parts of the forest and the maximum count for one night was 26 individuals in Oakley Wood on 9th July 2013.  In 2014 the moth was confirmed as a resident in Waterperry Wood with three caught on 30th May and another singleton on 17th June.