Wall Monograph

The Suffolk Argus

The fifth in a series of monographs on Suffolk’s seven BAP butterflies

Wall

Lasiommata megera

Status The Wall, or Wall Brown, has been allocated to the BAP category of “Research Only ” , in recognition of the inadequately understood decline of this formerly common resident. Over the past 30 years, it has lost 38% of its UK distribution, following a similar pattern to the Grayling, and becoming more coastal. In Suffolk, it is no longer found as a garden butterfly in the centre of the county.

Distribution The Wall has become lost from central Suffolk in the same way as the Grayling. It still flourishes on coastal wilderness sites like Orfordness, and is still found in small numbers in the northwest of the county, along embankments beside the Lark and Little Ouse, for example. However, it is now becoming an unusual sight for most people. The maps below contrast the 5 years of the Millennium survey with the most recent 5year period (in which 997 squares were surveyed).

Ecology The Wall is becoming rather choosy in its habitat preference, and is now unlikely to breed on areas of scruffy grass along fence lines and in unkempt gardens. Its favoured larval host grasses include Tor grass, False Brome and Wavy Hair-grass, species that grow in the wild, open places where it lives. It will not tolerate mown lawns or fertilized pasture.The adult butterflies bask on bare soil embankments in the sun, and individuals are short-lived, typically just a week or ten days. It has two generations, flying in May and again in August. The progeny of this second generation pass the winter as tiny larvae.

Monitoring The Wall has all but disappeared from the transects at Minsmere and the Fynn Valley, so only North Warren remains as a regular measure of the health of our populations. Sadly, the omens do not look good, as the recent decline has been abrupt. Counts of casual and garden sightings merely serve to confirm the deteriorating situation. The 2010 distribution map shows Wall in only 4% of the tetrads surveyed. The Suffolk Naturalists’ Society is running a single species survey in 2011. Selected tetrads will be checked at the margins of where the Wall has been fading away.

Conservation Butterfly Conservation has sponsored a postgraduate study of the causes of the decline of the Wall. No practical conservation measures are being taken in Suffolk, but safeguarding the sites where it is still found seems important. Given the progressive declines at protected sites like Minsmere and North Warren, it is clear that effective measures will not be easy.

Tailpiece The Wall is a sun-loving butterfly that likes to bask on rocks or south-facing walls. Thus it often lives up to its name.

Rob Parker Conservation Officer (Butterflies) and County Recorder

The Wall from an unusual angle by Douglas Hammersley

Archaeologist’s trench Forage harvesting heather

George Millins builds an animal refuge