This is the smallest of the British Cryptocephalus species. It is a shiny black in colour, with the legs and base of the antennae yellow. The male's head is also yellow but with a black line down the centre. The female's head is all black.
Adult beetles have been found during the months of June and July. Their larvae live at the edge of damp hollows that dry out in summer. The larvae live in little pots that look like mouse droppings. Its head is a perfect fit to the opening, and when it feels threatened it scurries into its pot and closes itself in.
This species was once much more widespread in England, having been recorded in the Norfolk Broads and north Lincolnshire. However, these might have been widely separated and extremely localised populations. The beetle was not found at any site after 1957 until 1980, when a single male was found at Pashford Poor's Fen near Lakenheath in Suffolk. Several more beetles have been found at the same site.
The Pashford pot beetle is listed in the UK Biodiversity Action Plan (UK BAP), and included in English Nature's Species Recovery Programme. Pashford Poor's Fen is a Site of Special Scientific Interest (SSSI) and managed by the Suffolk Wildlife Trust. In order to limit the loss of water to the fen, the SSSI boundary was extended in 1996 to improve control over the adjacent drainage ditches, and additional bunds have been installed to try and hold water levels higher during the summer months. Issues connected with the control of water resources on the site are to be addressed through the production of a Water Level Management Plan.
The management plan for the site is currently being rewritten with greater emphasis on the vegetation management of the wet fen areas where C. exiguus has been found. This will primarily concentrate on reducing the level of grazing in autumn and early winter. Future information will provide a better indication of the habitat management requirements of this species. Fencing has also been installed to control the grazing more effectively.
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