Slender Scotch Burnet Moths on Ulva

Slender Scotch Burnet Moths

Ulva is home to many species of wildlife, but one of the rarest is the small and stunning Slender Scotch Burnet Moth. This day-flying moth is now only found on a handful of sites, all of which are on Mull and Ulva.

Adults: the red and black adults are on the wing from mid June to early July. Their wings are thinly scaled which makes them appear translucent.  The males are more prominent, and can be seen congregating on food plants such as milkwort in good weather. The females are less active and can be spotted on bird’s-foot trefoils. The adults are not very active and rarely stray from their colony. Other food plants are cat’s ear and wild thyme.

Caterpillars: The larvae are a dark grey-green, with yellow and black spots along their side. They avoid areas of long grass and feed on bird’s-foot trefoil where it is growing abundantly in short grass. The caterpillars can be seen basking on stones, bare soil or mossy outcrops.

Habitat: The moths inhabit grassy banks and small cliffs on sunny, south-facing coasts where bird’s-foot trefoil grows. As the species prefers low vegetation it establishes breeding colonies where rock and soil slides are likely. This short herb-rich grassland is often associated with basalt rocks, as on Ulva. This instability prevents the vegetation from getting well established. Grazing also benefits the creation of suitable habitat. Threats to the species include bracken invasion causing by under-grazing, and the spread of Cotoneaster species.

Butterfly Conservation Scotland has carried out conservation work over the last few years to halt the decline of the species, and to educate people locally about the importance of these species and many others that can be found in the area.

Similar Species: the Slender Scotch Burnet can be confused with other members of the Burnet family, as well as Cinnabar moths.

Further Information: Butterfly Conservation Scotland’s website has a profile of the species plus a leaflet on Scotland’s Burnet and Forester Moths.