Report of the Wiltshire Sawfly Recorder, 2010
By K. John Grearson
Click here to download a copy of this report
Despite a continuation of the patchy weather in spring and summer which has been a feature of recent years I was able to run my three Malaise traps for a while at Moreleaze Farm, Minety. This farm has recently entered Higher Level Stewardship and the survey was a baseline study of the sawfly fauna plus any other wildlife recorded during my visits. The site consists of four field of neutral pasture which have not been farmed intensively for many years plus a well-established wildlife pond. The result of this survey was a sawfly list of 60 species, including the second county record of Pachynematus lichwardtii Konow , the first having been recorded in 1971 at Wishford. Also present was a colony of the Iris Sawfly, Rhadinoceraea micans (Klug) which, in Wiltshire, is only known currently at four other sites.. Another species, Craesus alniastri (Scharfenberg), found on Alnus glutinosa, in Wiltshire, only recorded at one other site, nearby at Ashton Keynes. The species total at Moreleaze Farm was much higher than expected and further study in better weather conditions should produce a few more as should the planned enhancement of the environmental management at the site.
In total, 260 records were added to the database of which 14 were received from observers other than the county recorder. The county database now holds 4200 records of 301 species.
The notes below show the five species recorded in Wiltshire for the first time, although one of them is a belated entry from 2008.
Amauronematus tunicatus (Zaddach) - On 12th May 2009 a presumed Amauronematus larva was beaten from Salix cinerea at Bentley Wood. It emerged on 5th April 2010 and was identified as a female of this species. Regarded by Benson (1958) as a local species in Britain.
Amauronematus vittatus (Serville) – A male was beaten from Salix at Ashtojn Keynes on 23rd April 2010. Another local species.
Neodiprion sertifer (Geoffroy in Fourcroy) – Steve Covey discovered larvae of this local species on Pinus silvestris at Horse Down, Tilshead on 7th June 2008.
Pachynematus kirbyi (Dahlbom) – Due to a recent taxonomic change this species has been separated from Pachynematus clitellatus (Serville) with which it has been aggregated for many years. The latest record was at Moreleaze Farm but some of the earlier records of P. clitellatus probably refer to this species.
Trichiosoma tibiale Stephens – A Trichiosoma larva was beaten from a Salix hybrid at Somerford Common on 12th June 2009. It fed well in captivity and made a cocoon on 1st July 2010 from which it finally emerged as a male on 25th April 2010. Determination of adult Trichiosoma is especially difficult and Finnish keys were used in this case, There appears to be two types of this species, one with larvae feeding on Crataegus and one on Salix. The adults of both types appear to be indistinguishable but the larvae are different. Larvae of the Salix-feeders have a yellow patch on the face when in the final instar whilst those of the Crataegus-feeders have a reddish face. Because of the similarity of the adults they are treated as a single species for the time being. DNA sequencing could probably resolve any confusion. Distribution of this species in Britain is unknown since it is seldom found.
18th February 2010
