Basil-thyme case-bearer moth  (Coleophora tricolor)

Classified as Endangered in Great Britain (3).

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 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).

Inhabits unimproved grasslands of light grasses, forest tracks and wartime hard-standings (2).

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).

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).

Further reading on moths:
Leverton, R. (2001) Enjoying moths. Poyser, London.
Emmet, A. M. (1996) The moths and Butterflies of Great Britain and Ireland, 3. Harley Books, Colchester.

Information authenticated by Gerry Haggett.

• Pupating: the process of forming a pupa, the stage in an insect's development, when huge changes occur that reorganise the larval form into the adult form. In butterflies the pupa is also called a chrysalis.
• Pupation: the process of becoming a pupa, the stage of an insect's development, when huge changes occur that reorganise the larval form into the adult form. In butterflies the pupa is also called a chrysalis.

1. National Biodiversity Network Species Dictionary (September 2002) http://www.nhm.ac.uk/nbn/
2. Haggett, G. M. (2002) Pers. comm.
3. UK BAP Species Action Plan (September 2002): http://www.ukbap.org.uk
4. Parsons, M. (2001) The European status of the UK Biodiversity Action Plan moths. The Entomologist's Record and Journal of Variation. 113: 49-62.
5. 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.
6. English Nature Habitat Associations. (September 2002): http://www.english-nature.org.uk/baps/species/overview.asp?Id=233&Habitat_Key=14&sType=C&PrevPage=habitat