Occurrence of the Tissue Moth in chalk tunnels at Bury St Edmunds Observations have been made for 76 winters since 1947/48 mainly searching for bats but taking note of other wildlife on each occasion. Apart from bats there were spiders, mosquitos and other flies such as the drone fly, Eristalis tenax and most conspicuously, Herald moths, Scoliopteryx libatrix. These colourful moths were mostly found in the cooler outer areas of the adits where dim light penetrated. Numbers were never counted but historically on occasion there were perhaps up to 100 or more, although the number found in the last twenty years have noticeably reduced.
On four surveys in winters, 29 January 2005, 31 December 2007, 5 January 2014 and 30 January 2016 single specimens of the Tissue moth, Triphosa dubitata, were found hibernating in the chalk adits. These were found generally deeper in the tunnels, more or less in areas of complete darkness. Because in each winter the surveys are conducted around the New Year (either before or after) and at the end of January, it was evident that either on the first or second search the moths were not present. This shows the moths enter or leave the tunnels in January.
In Britain, these moths tend to be mostly found in areas with chalk or limestone substrates, predominately in southern Britain. Extensive research in limestone mines by this author particularly working in Wiltshire, showed often hundreds of specimens, sometimes gathered in clusters of up to 20 moths. In addition, at the Ketton Cement works in Rutland where one of the principal rocks is limestone, a large 90m long ‘cave’ was constructed specially for bats in the 2001. From the first winter after completion, numerous Tissue moths were found in hibernation together with some herald moths. Bury St Edmunds is about 90 km south east of Ketton.
The caterpillars feed on buckthorn (Rhamnus catharticus) and alder buckthorn (Frangula alnus). The former prefers alkaline soils but the latter is often found in wetlands with neutral or even acid substrates.
Note there is a lot of variation in the colour of this moth but in these photographs taken in Wiltshire limestone mines, the one on the right is covered in condensation so appears much lighter than if it was dry.
Martin Sanford kindly reminded me there has been a campaign to plant buckthorn in east Suffolk to aid the Brimstone butterfly. In time, this may help the Tissue moth as
Suffolk Records
Clearly the Tissue moth appears uncommon throughout Suffolk; most of the recent records are post-2000 (6) and nine up to 1999 plotted on a 2km square scale (map above from Suffolk Moths website Sept. 2023). This is slightly surprising as it is a large moth and easily identified. At rest, it is about 40mm across. The fact most records are in the extreme east, may reflect the amount of light trapping carried out in that area.
[Neil Sherman adds: The Tissue moth is known to be weakly attracted to light hence why there are few records as that is the most common recording method people use. I've never found any larvae myself on Buckthorn in West Suffolk despite doing larval survey work out in that part of the county, so I would say it is genuinely rare. VC25 is, and always has been better recorded than VC26, with more recorders. There has been more survey work done in VC26 more recently, but the Tissue hasn't been found. Looking at the distribution across East Anglia, there are more records in Cambridgeshire than in the other two counties so perhaps the hibernating moths are wandering in from over the border.]
Robert Stebbings
Willowbrook House, Kings Cliffe , Peterborough , PE8 6XN