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Update on the Suffolk Branch Action Plan for Moth Species (Part 2
Update on the Suffolk Branch
Action Plan Moth Species (Part 2)
by Tony Prichard
This article completes the update on the moth species covered in the Suffolk Action Plan. The current status of some species is of major concern whereas others seem to be faring relatively well. The Branch and Suffolk Moth
Group are actively involved in the surveying
and monitoring of some of these species and have some encouraging results as well as some disappointments.
Bordered Gothic Heliophobus reticulata marginosa
Since the regional action plan was written this species has continued its decline. A colony identified in Kent in 200 I returned negative results in 2002 and despite being a National Moth Night (NMN) target species in 2002 it appears no records were made in 2002. In 2003 an individual, apparently of the resident form, was recorded in Norfolk at Honing by Phil Heath, suggesting that the species may still be resident. A singleton was recorded from Landguard in 2000 by Nigel Odin and presumed to be a migrant. A record from Thetford in 1995 by Steve Dudley has come to light and updates the last known year this species was recorded in the Brecks. Not far from the location of this record is Barnhamcross Common and the Branch and the Suffolk Moth Group have been recording at this site in recent years but with no sight of any Bordered Gothic. Just to the south of the common is the RAF Barnham training camp and this his been subject to occasional moth recording but again there has been no sign of Bordered Gothic. The Brecks is not an underrecorded area, with moth recorders from around the country visiting the area, so unless the species is at a very low ebb it would appear strange why this moth is not recorded more often in the area. General moth surveying of the Brecks will continue and visits to previously known sites not recently surveyed will be made over the next year or so.
White-spotted Pinion Cosmia diffinis
This formerly widespread species underwent a severe decline as Dutch Elm disease affected its larval foodplant. Recently some encouraging reports of sightings have been received from nearby counties; Huntingdonshire, Cambridgeshire and Essex. The most recent county reference I have for this species is from the Walberswick area in the late 1990s, although I've still to track down the precise details of the record. David Young and myself searched the site for White-spotted Pinion larvae early on in 2003 but no larvae of the target species were found. A visit to the same site by the moth group with lights later in the year in August failed to attract the adult moth. The Moth Group has targeted occasional moth nights for this species in recent years but with no success. I understand that it has a liking for 'sugar' and better results may be achieved with this than with light so we'll probably try chat technique in the future. Despite the recent negative results I would think that the chance of this moth still residing in Suffolk remains high and surveying for this species will continue.
Marbled Clover Heliothis viriplaca
This species continues to be recorded in low numbers from both the Breckland areas of Suffolk and the Suffolk coastal areas around Aldeburgh, Thorpeness and Sizewell. Numbers of records
received each year remain low although some years prove better than others. This may suggest that the population is relatively stable but at low density. It might also mean that the species may be vulnerable to slight changes in the habitat that might rip the balance against its favour. This year (2003} I carried out targeted searches for this species looking for the moth in the coastal and Breck areas in an attempt to assess its current status. I did not manage to locate it in any of its coastal haunts or in the Brecks. Fortunately, David Young had more success when he recorded it at Maidscross Hill, a known locality for the moth, during the year. Due to the lack of success in finding this species in 2003 searches will continue in 2004.
Four-spotted Tyta luctuosa
A day-flying species that was last recorded in Suffolk in the Brecks during the very early 1990' s (Thetford Forest, 1991, Gerry Haggett}. Various recorders have made visits in recent years to sites where it was known to occur but all have proved negative. Currently in Britain there appear to be three sizeable populations of this moth and these are monitored each year and currently seem stable. A record of this moth in Essex in 2000 opens up the possibilities that colonies of this moth may exist un-discovered in areas of Suffolk. The caterpillar feeds on field bindweed (a rather common plant} and there seems to be a requirement for bindweed that is on open sunny verges or disturbed ground - presumably hot microclimates. This species would be worthwhile keeping· an eye out for around the county wherever the foodplant occurs in a suitable habitat from mid-May to August.
Buttoned Snout Hypena rostralis
Since rhe action plan was written for this species its place on the list has come under some scrutiny. The approach taken is that if the species does not warrant its BAP status then evidence must be provided to produce a case for its removal. The adult moth does not respond to light very well so light trap records have been rather low on the ground. The larva feeds on hop (Humulus) and can be easily found by 'beating' the foodplant. Larval surveys in recent years in sourheastern counties have proved very productive and in 2003 I undertook a survey for this species in Suffolk with the aim of recording it from as many I 0km squares as possible. This proved very successful and along with additional records from Sharon Hearle, Neil Sherman and Andy Musgrove the larva was recorded this year from thirty 10km squares. With previous adult records the moth has now been recorded from forty-one I 0km squares in Suffolk, good evidence that the moth is well distributed in the county. I suspect that most places in Suffolk where the foodplant occurs will be found to support the larvae, my experience was that over most of Suffolk it was nor hard to find larvae if hop was present.
Shaded Fan-foot Henninia tarsicrinalis
From a county viewpoint I suspect that there has been little change in the status of this species since the original plan was produced. The moth remains largely confined to the more easterly areas of the county with a single recent record from the west of the county (Great Cornard, Stuart Reed}. New sires are discovered for this species each year bur I do not think these indicate recent spread and colonisation by the moth. I suspect we are still in the process of discovering the moth at existing haunts where it may well have been present for many years. As this species seems to be in a reasonably healthy state it is not my intention to push for specific surveying for this species as additional records/sires are gained through our normal moth recording activities. This species occurs at a regularly recorded sire and numbers will be monitored over the years. As far as I understand wild larvae have not yet been found and research into the earlier stages of this moth and the species' habitat requirements could prove interesting.
Lunar Yellow Underwing Noctua orbona
A moth that has previously undergone a national decline leaving occasional scattered colonies across rhe country with its main stronghold being in the Brecks. Records of the moth at light in the late
l 990's have suggested that populations may exist in the Sandlings. In the last few years Gerry Haggett has been leading work into the larval habitat requirements of this moth in the Brecks. Some interesting findings have come out of this work especially in relation to the potentially adverse effects of sheep grazing in habitat management and the larvae utilising a transitory habitat in conifer plantations on Wavy Hair Grass (Deschampsia flexuosa). Over the winter of 2002/2003 some of the branch and moth group members carried out similar survey work in the Sandlings following some promising results from initial surveying in early 2002. This work showed that sizeable populations of the moth occur at most suitable locations in the Sandlings and would appear to utilise additional variations on acidgrassland habitat in comparison to the Brecks populations. I am unsure whether the discovery of the extent of the Sandlings populations is indicative of an upturn in the species fortunes. This species would appear to come to light infrequently and can be confused with the commoner Lesser Yellow Underwing (Noctua comes). I suspect that the moth could well have been overlooked in the past, especially as the Sandlings is probably under-recorded in comparison to the Brecks. Larval survey work is expected to continue this winter.
Square-spotted Clay Xestia rhomboid.ea
This widespread but local species seems to occur most frequently in the southeastern areas of the country. In Suffolk the coarse distribution would appear to align with that of the Lunar Yellow Underwing - another species where the stronghold populations are thought to occur in the Brecks with additional populations in the Sandlings. It is only in recent years that the larvae have been found feeding in the wild and initial findings seemed to indicate chat there was a preference for nettles growing under elm trees. Earlier this year some surveying was done by the moth group at sites where the adult has previously been recorded where there was nettle under elm trees. This met with some success and four larvae were found feeding on nettle and red campion. Additional foodplants have been noted elsewhere in the country this year and given the behaviour of closely related moths it would not be a surprise if this species turned out to eat a wide variety of lowgrowing plants. Unlike the Lunar Yellow Underwing it is not easy to narrow down on suitable habitats to survey for this species (nettle and elm being· rather common). Unless our understanding of its habitat requirements improve, recording of the adult at light will remain the main means of searching for this species. In the lase 6-7 years records of this species have increased (at least based on the records in the database) and possibly of more relevance is the increase in the number of locations at which it is recorded each year under 5 locations per year in the early nineties up to 13 sites in 2001 and 12 sites in 2002.
Pale Shining Brown Polia bombycina
This species seems to be suffering similar fortunes to the Bordered Gothic. There have been no records of this species in the county since the regional action plan for this species was put together and there only appears to have been one record nationally in 2002. Our ignorance of the life history and particular habitat requirements for this moth makes targeted searching and managing for this species extremely awkward. Currently I do not feel very optimistic over the fate of this species in the country.
Cokophora tricolor
The only micro-lepidoptera with BAP status and apparently restricted to the Brecks in Britain. This is one of a group of micro-lepidoptera where the larva forms a case that encloses its body, presumably providing a level of protection. This species initially uses a detached floret of Basil Thyme as its first case and later on switches to cases made from pieces of grass. Surveying and monitoring of this species continues to be undertaken by Gerry Haggett in the Brecks with four areas being found to support the moth. The foodplant, Basil Thyme, appears to be subject to fluctuations in its population but the moth has been found on quite small colonies of the plant. Habitat management proposals have been put into
effect to hopefully benefit the plant and this species.
References
Davis, T., Green, D.G., Parsons, M. S., Bourn, N.A.D. (Eds.) 2003. Lepidoptera Conservation Bulletin: Number 4: April 2002 - March 2003. Butterfly Conservation.
Haggett, G.M., 2002. Lunar Yellow Underwing, Noctua orbona (Hufnagel), larval survey in Norfolk and Suffolk Breckland. Butterfly Conservation.
Joy, J. 2000. Regional Action Plan for East Anglia. Butterfly Conservation.
Mann, J & Prichard, T. 1998. Suffolk Action Plan. The Suffolk Branch of Butterfly Conservation.
Parsons, M. S., Green, D.G., Bourn, N.A.D. & Waring, P. (Eds.) 2000. Lepidoptera Conservation Bulletin: Number 1: April 1999 - March 2000. Butterfly Conservation.
Parsons, M. S., Green, D.G., Bourn, N.A.D. (Eds.) 2001. Lepidoptera Conservation Bulletin: Number 2: April 2000 - March 2001. Butterfly Conservation.
Parsons, M. S., Green, D.G., Bourn, N.A.D. (Eds.) 2002. Lepidoptera Conservation Bulletin: Number 3: April 2001 - March 2002. Butterfly Conservation.
Distribution Maps
Bordered Gothic
White-spotted Pinion
Marbled Clover
Distribution Maps
Four-spotted Lunar Yellow Underwing
Buttoned Snout Square-spotted Clay
