This species can be distinguished from other similar Fan-foot moths by its pale hindwings and ochreous grey forewings (1). The forewings are crossed by three slightly darker lines (4). Young caterpillars cannot be reliably identified from other similar Fan-foot moth species, but medium and larger sized caterpillars can easily be identified. They have orangeish-brown heads and warm brown bodies with a fine black dorsal line across all body segments. The bodies of older caterpillars are even more obviously orange coloured, while similar species have greyer heads and greyish-brown bodies with black dorsal line at most only along abdominal segments (3).
Adults fly after dusk (usually very late in the night) between late May and early July (3). Caterpillars occur from July to April (1), feeding on wilted oak leaves (3). The caterpillars usually overwinter when almost fully grown (1). Snapping one metre long oak branches at head height in late May / early June and leaving them hanging on the tree to wilt creates ideal habitat to search for the caterpillars in August and September (3).
Unfortunately, this species is no longer common, as the English name suggests. It was once known throughout southern England north to Cumbria and Wales (3), but at present persists in just a handful of oak woodlands in south-central England and the Midlands. Elsewhere the range extends eastwards throughout most of Europe to Russia and Japan, but the precise status of the species is not known (2).
Inhabits broadleaved woodlands. All remaining populations occur in oak woodlands on both clay and sandy soils. Ideal habitat appears to be humid ancient semi-natural woodland with under-storey or mature coppice (aged 15 to 70 years) (3).
The causes of the precipitous decline of this species are not known (2), although the unusual wilted oak leaf habitat for caterpillars could be vulnerable. Variations in climate, with damp and particularly dry / windy conditions may threaten the survival of caterpillars (reductions in areas of mature coppice in woods may also affect this). Furthermore, parasitism of caterpillars by parasitic wasps may be an important factor (3).
The Common Fan-foot moth has been identified as a priority species by the UK Biodiversity Action Plan; the Species Action Plan aims to maintain and enhance all current populations and reintroduce five new populations within the historic range before the year 2010 (2). Proposed measures to help the species include suitable habitat management and increasing the area of suitable habitat available (2). Research is currently underway in order to discover more details about this species; this should hopefully guide conservation management (3).
The UK Biodiversity Action Plan for this species is available at UK BAP.
Coppicing is a traditional form of woodland management in which trees are cut close to the base of the trunk. Re-growth occurs in the form of many thin poles. Coppiced woodlands are cut in this way on rotation, producing a mosaic of different stages of re-growth.
Interaction in which one organism derives its food from, and lives in or on, another living organism (the host) at the host's expense.
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