Mothy Mutterings – April 2015

In England there are concerns for the population of Dark Bordered Beauty vespertaria at its sole extant site near York. Terry Crawford and others have been monitoring the population for a number of years, walking transects on a regular basis during the flight period. Counts have seen a year-by-year decline since 2009. An MSc student at the University of York has been able to compare data on creeping , the larval foodplant, collected by students working on the in 2005 and 2013. Analysis of this has detected a three-fold reduction in the plant density across the whole transect with the reduction increasing to nine- to 14-fold in areas of highest plant density in 2005 which included “hotspots” for the moth at that time. Principal component analysis has shown that in 2005 plants with larvae were significantly larger than random plants, and that the average size of plants has significantly declined so that in 2013 no plant was as large as the median plant on which larvae were found in 2005. One possibility is that changes in shepherding practice in the late 2000s may have led to increased grazing pressure on the Creeping Willow, but other factors including climate and disease may also have a role. Butterfly Conservation, in conjunction with Natural England, have been suggesting that a number of cages should be placed on the site to protect selected areas supporting the foodplant from grazing, and these could be supplemented with plug plants that have been grown from Strensall seed. If within the exclosures there is no improvement in the Creeping Willow, then this would weaken the case for grazing being the issue. The Ministry of Defence has supplied these cages (nine) and they were put in place in late April by Landmarc, with assistance from Butterfly Conservation staff, Terry and Penny Relf, ahead of the start of this year’s sheep grazing. It is hoped that a student from the University of York will undertake a baseline vegetation survey both inside and outside these cages in the coming summer. In addition, some discoloration of Creeping Willow leaves was noted last autumn, possibly indicating an infection but too late in the season for investigation; plant pathologists are on stand-by in case of a recurrence this year.

Last year we secured funding from Veolia, through a landfill tax credit, with matched funding coming for other sources, including the Patsy Wood Trust, for work on the Striped Lychnis Cucullia lychnitis around Winchester, Hampshire. This has included a significant amount of scrub removal and disturbance of the soil to expose the chalk on well-known sites for the moth along the A31. Unfortunately, in recent years both the moth and the larval foodplant have declined in these areas as scrub has encroached and taken over. Just a single larva was found on one of these sites on a visit in late July 2014. The aim of this project is to restart the vegetation succession and to promote the growth of Dark Mullein, whilst knowing that the moth is still in the general area. Some plug planting of Dark Mullein will also be carried out to give the foodplant a helping hand. Much of the winters’ management work has been completed, and although some of these areas look quite bleak currently, being large expanses of bare chalk, it is hoped that within a few years the moth will re-colonise, along with some of the downland butterflies that used to occur here. Several volunteer work parties undertaking a variety of tasks are being planned for later this year to further this initiative.

Various additional site visits have taken place during April, these have included the annual monitoring of Scythris siccella at its sole UK site. Disappointingly only two larval tubes were located. It could be that the season for this species is a late one this year, rather than reflecting worryingly low numbers (following the low minimum counts of six and seven in 2013 and 2014 respectively). A second count is now planned for early May. The Forester Adscita statices is a species that we are trying to more accurately determine its habitat requirements. Whilst the adults are relatively straightforward to find where they occur, the larvae are a different matter altogether. Indeed if you have found larvae of the Forester in the wild we would like to hear from you! Last year a single visit to a wet grassland site known to support the species failed to locate the larva. This year a calcareous grassland site, a Butterfly Conservation reserve, was searched, and after 15 minutes a single larva was found in the early morning. This was almost fully grown, sitting almost fully exposed in a slight depression on the south facing slope of an ant hill in an area of rough grassland. Despite sunny conditions no more were found during two hours of searching. Unfortunately with a sample of one, this does not take us much further forward on habitat requirements, although we now have a photograph of the larva! A site visit was made to a locality for Agonopterix atomella to determine the state of the season for that species and its foodplant, Dyer’s Greenweed. During the visit it was clear that invading scrub is becoming an issue on a couple of the fields, this fed back to the site managers. Searches for the Sloe Carpet Aleucis distinctata have been undertaken in Surrey by Butterfly Conservation staff, with the species being found at a well-known location. Butterfly Conservation staff accompanied by others (seven people in total) also undertook a search for the larvae of the Silurian Eriopygodes imbecilla, building on previous years’ survey work. The search was very successful, with over 80 larvae found, including records from a new 1km square, locating the most northerly breeding site in the country and also finding a very few larvae feeding on Crowberry, this a new foodplant for the species in this country. Finally, we have also been asked to find a very local species of moth for the forthcoming BBC Springwatch, and at the time of writing we have only been able to find two, whether that will be enough for filming remains to be seen.

Several of the above sightings mentioned, along with many additional observations are reported in the Priority Email Newsletter. This newsletter reports on the various Priority moth species that have been found at around the time of production, based on actual observations. We are very reliant on you, the recorder, to make us aware of sightings of Priority species a list of UK Biodiversity Species - this spreadsheet also covers those species listed on Section 41 and 42 of the NERC Act (2006), the Scottish Biodiversity List and the Northern Ireland Priority Species list, can be found here. It excludes the so- called widespread and common but rapidly declining ‘Research only’ species. By compiling these sightings and producing this newsletter regularly we aim to encourage survey for these Priority moths, thereby enabling a better understanding of their status. If you find any of the Priority species then please let us know as soon as possible – contact [email protected]. Over 250 editions of this newsletter have now been circulated.

Cooler nights have again continued over much of the month, although there have been some milder evenings. Because of the cool conditions there have been many continued reports of low numbers. However, many late spring/early summer species are beginning to put in an appearance, with reports of Small Chocolate-tip Clostera pigra, several of the Prominents, Lime Hawk Mimas tiliae, Grey Aethalura punctulata, Maiden’s Blush Cyclophora punctaria and White Ermine Spilosoma lubricipeda, amongst others, all being reported. During March it seemed as though the Red Sword-grass Xylena vetusta was having a good year, at least in parts of the south. In April it would appear to be the turn of the Brindled Beauty Lycia hirtaria, with numbers being seen at several sites, and even the second only sighting for Portland, Dorset being made, details can be seen on the Portland Bird Observatory blogspot. Time will tell if these first impressions are true!

The larval cases of Coleophora lineolea can be relatively easy to find in May. This species is associated with black horehound and hedge woundwort, and occasionally other labiates. In gardens it can often be found on lamb’s-ear. The feeding damage is often large and obvious on the upperside of a leaf, with the distinctive larval case being found on the underside. Images can be seen on UK moths and UK fly mines.

The Moth Team