Pot beetle (Cryptocephalus primarius)

SizeFemale length: 6-8 mm
Male length: 5-7 mm

Classified as Endangered in the UK.

This rather shiny beetle (one of the larger Cryptocephalus species) has orange wing-cases (elytra), each with five black spots. The head and thorax are shining black. Both sexes have black legs and antennae, which are relatively longer in males.

Although this beetle has been recorded from five sites as far apart as Perthshire and Dorset, its last known haunt was Rodborough Hill, near Dursley in west Gloucestershire. Outside of the British Isles, it is found in central and southern Europe.

The adult beetles are associated with common rock-rose (Helianthemum nummularium), growing on warm, calcareous hillsides. The preferred adult and larval host plant is probably rock-rose.

Very little is known about the life of these beetles. The adults are found between May and July. Larvae develop at the base of the host plant, probably feeding on leaf litter. There is no evidence to suggest a link with ants, which have been shown to pay no attention to Cryptocephalus eggs.

The chief threats to this species are the loss of the calcareous grassland habitat and inappropriate grazing regimes.

This species of leaf beetle is listed in the UK Biodiversity Action Plan (UK BAP) and included in English Nature's Species Recovery Programme. It is important that more information is gathered about this species' habitat requirements and its ecology, as well as the other members of the Cryptocephalus group of leaf beetles.

The rare UK members of the genus Cryptocephalus were subjects of a post-graduate study by Ross Piper of Leeds University.

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact: arkive@wildscreen.org.uk