Adults of the endangered Basil-thyme Case bearer have dusky ochreous forewings with delicate silvery-white streaks (2). Both the fore- and hindwings have long silky hairs, the long white antennae are chequered with black (2). The caterpillars of this extremely rare species live inside cases attached to vegetation (1).
In early autumn, the caterpillars initially feed within the seedheads of basil-thyme (Acinos arvensis). As they age, they move to feed on grasses, where they spend the winter, still protected inside their cases. They feed again during the following spring when they construct a new case from the cuticles of blades of grass (5), before pupating. Adults fly during July and early August (3).
In Great Britain, this moth has only ever been recorded in modern times from the Brecklands of Suffolk and Norfolk. Until recently, caterpillars had been found at just two sites, and adults at a third (3). However, recent research and survey work has discovered strong populations and a number of smaller sites (2). At one of the sites in Suffolk, the habitat has become unsuitable for the species, and it has not been seen there since the 1970s (3). Elsewhere, the Basil-thyme Case-bearer has only been recorded from one site in Switzerland (3), and from two locations in Estonia (4).
The foodplant has declined with the loss of unimproved heathlands in the Brecklands (3). The major centres for this species are today free from sheep grazing, but sheep grazing remains the major threat in the Brecks outside Thetford Forest (2).
The Basil-thyme Case-bearer is a priority species under the UK Biodiversity Action Plan (UK BAP). The Species Action Plan that has been produced for this moth aims to maintain current populations, with the establishment of at least 10 viable populations by 2010, using introductions where needed (3). This rare moth is also included in English Nature's Species Recovery Programme (6).
Parsons, M. (2001) The European status of the UK Biodiversity Action Plan moths. The Entomologist's Record and Journal of Variation. 113: 49-62.
Haggett, G. M. (2000) The early stages of Coleophora tricolor Walsingham 1899 (Lep. Coleophoridae) on the Norfolk Breck and their significance for conservation management. Entomologist's Gazette51: 215-234.
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