Slender Scotch burnet (Zygaena loti scotica)
|Size||Adult wingspan: 24-30 mm (2)|
Classified as Rare in Britain (3).
The Slender Scotch Burnet is a striking red and black moth that can be distinguished from other burnet moths by its hairy abdomen, the presence of a kidney-shaped black mark in the outer area of the forewing and the narrower black border on the hindwings (3) (2). Burnet caterpillars are typically stout and strongly patterned with green yellow and black (4). In this species they are dark grey-green, with indistinct, small yellow and black spots along the side (2).
Although Zygaena loti is found throughout central Europe, the subspeciesscotica is endemic to Scotland (5). It has an extremely restricted distribution in Scotland, and is classified as rare. It is at currently found only on the Hebridean islands of Mull and Ulva (3). Colonies in the north of Mull and on the mainland at Morven (Argyllshire) have become extinct (5) (3).
Inhabits south or south-west facing grassy banks and low cliffs close to the sea where the larval foodplant bird’s foot trefoil (Lotus corniculatus) is found (1) (5). The short vegetation on these slopes is maintained by grazing and erosion (5).
The moth is single-brooded. Adults are present from June to early July. They fly during the day in sunshine and visit the flowers of the foodplant, bird’s foot trefoil. The caterpillars are present from August to early may of the following year (3). They spend the winter in diapause and some caterpillars re-enter diapause immediately after emerging. It is unclear how many successive years caterpillars may do this, and it is thought that this phenomenon may partly explain why the populations of adult moths fluctuate greatly from year to year (5).
In some areas a lack of grazing may lead to vegetation succession and eventually to bracken growth, which removes suitable habitat for this species (2). Other threats include the increasing isolation of remaining colonies and collecting of adults and caterpillars (5) (2).
The Slender Scotch Burnet is listed as a priority species under the UK Biodiversity Action Plan, and a Species Action Plan has been produced to coordinate conservation efforts aimed at this moth (5). One of the aims of the Action Plan is to maintain all current known populations of the Slender Scotch Burnet. Targeted habitat management is already in place in some areas. Most of the current populations occur within Sites of Special Scientific Interest (SSSIs), and National Trust for Scotland owned land, and so the needs of the species are considered at these sites (5). Nevertheless, it is continuing to decline (2).
- Abdomen: in arthropods (crustaceans, insects and arachnids) the abdomen is the hind region of the body, which is usually segmented to a degree (but not visibly in most spiders). In crustacea (e.g. crabs) some of the limbs attach to the abdomen; in insects the limbs are attached to the thorax (the part of the body nearest to the head) and not the abdomen. In vertebrates the abdomen is the part of the body that contains the internal organs (except the heart and lungs).
- Diapause: in insects, a temporary pause in development and growth with a definite physiological basis. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Hibernating: a winter survival strategy characteristic of some mammals in which an animal’s metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is ‘diapause’, a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
- Larval: of the stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but are unable to reproduce.
- Single-brooded: (also known as ‘univoltine’). Insect life cycle that takes 12 months to be complete, and involves a single generation. The egg, larva, pupa or adult over winters as a dormant stage.
- Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
- Succession: the progressive sequence of changes in vegetation types and animal life within a community that, if allowed to continue, result in the formation of a ‘climax community’ (the last stage in a succession where the vegetation reaches equilibrium with the environment).
- NBN Species Dictionary. (Feb 2003). Available on-line from: / http://nbn.nhm.ac.uk/nhm/
- Young, M (2004) Pers. comm.
- Skinner, B. (1984) Colour identification guide to the moths of the British Isles. Penguin Books, Harmondsworth
- Carter, D. J. (1986) A field guide to caterpillars of butterflies and moths in Britain and Europe. Collins, London.
- UK BAP Species Action Plan for Zygaena loti scotica. (November 2003): www.ukbap.org.uk