Scotland’s mountains are famed for their wonderful landscapes and iconic wildlife. However, to many this conjures up thoughts of majestic Golden Eagles, approachable Ptarmigan or bounding Mountain Hares. However, Scotland’s mountains are also home to many species of scarce and specialised moths that have adapted to live in this hostile environment. Most of these are very under-recorded as few lepidopterists regularly venture onto the high tops, whist many hillwalkers are mostly oblivious to their presence, soaking in the wonderful panoramas unaware of fluttering or crawling moths around their boots.
Remarkably several of these species are day-flying, for instance, the very aptly named Broad-bordered White Underwing. On the wing in May and June, and confined to Scotland in the UK, it has a very swift and darting flight and is almost impossible to follow. When it lands, usually on bare ground and rocks, its greyish brown wings provide excellent camouflage and therefore it is most often encountered as it flies off rapidly from beneath your feet, hopefully giving the observer the chance to glimpse the white patches on the upper side of its hindwings.
Similarly, the Black Mountain Moth, that is on the wing about a month later, in June and July, is similarly confined in the UK to Scotland’s mountains. In poor weather this moth tends to creep about, almost spider like as it crawls rather than flies, over the vegetation.
Many people will be familiar with the Six-Spot Burnet found commonly south of the border but having a more coastal distribution in Scotland with their characteristic six crimson spots on their very dark bluey black wings. However, the Six-spot has a very rare upland cousin the Mountain Burnet that is only known from around six colonies all within a handful of kilometres of Braemar. The Mountain Burnet has five rather than six crimson spots on its wings.
These species are all found above around 600m an elevation when the heather becomes shorter, less dominant reflecting the harsher conditions at these higher altitudes. This results in more of a mosaic habitat with the wind-clipped heather growing amongst mosses, rocks, lichens and other upland plants especially Crowberry. One adaptation these moths have is having hairier, better insulated bodies, and a two-year life-cycle as they overwinter twice as a caterpillar being in this feeding stage for at least eighteen months reflecting the colder and harsher conditions and therefore the need for a longer feeding period.
There is also a suite of much smaller micro-moths that inhabit Scotland’s higher hills. These tend to be far more elusive due to their size making them easily overlooked unless being specifically sought after. They are also far less studied so less is known about their exacting habitat requirements or larval foodplants or even have fully adopted and recognised common names. These include species such as Catoptria furcatellus (Northern Grass-veneer), Udea uliginosalis (Mountain Pearl) and Ethmia pyrausta (Mountain Ermel). Their elusiveness is highlighted by the latter species. It was formerly only known from a single specimen taken in the 19th century until it was discovered in 1996 in the Cairngorms. It has subsequently been found in the last few years at a couple of sites in Easter Ross and the caterpillars found feeding on Alpine Meadow-rue.
So the next time you are lucky enough to be out in the Scottish hills, bagging Munros or simply enjoying the views and tranquillity, especially but not necessarily on those few yet wonderful sunny and warm days, take a little time to look around you for some of Scotland’s iconic montane insects.
Please report any sightings to Butterfly Conservation Scotland Scotland@butterfly-conservation.org or use the wildlife recording app irecord, so that we can get a better and more accurate understanding of their distribution. Most species will be identifiable from a half-decent photograph or description.
To find out more about Scotland’s upland butterflies and moths check out Butterfly Conservation’s Upland Butterfly and Moth leaflet on our website.
On Thursday 3rd June, and again on Saturday 5th June (10-11am) you can attend Butterfly Conservation Scotland’s Munro Mountain Moths virtual workshop, hosted via Zoom. You can book a place using our online Virtual Priority Butterfly and Moth Workshops 2021 booking form which can be found here