Weevil

Very little is currently known about the ecology of this species. The adults are associated with bracken (Pteridium aquilinum), and feed on climbing corydalis (Ceratocapnos claviculata), leaving distinctive 'half-moon' feeding damage on the leaves (5). Studies have shown that in captivity, the adults are usually nocturnal, and hide in bracken litter during the day (5). Adults have been found in the wild between March and August and December and January. Highest numbers occur from late April to the end of June. This suggests that this species breeds in summer, and the new generation of adults overwinters after emerging in August. However, more research is needed to determine if this is the case (2). Larvae belonging to this group of weevils live inside plant roots, however, the larvae of this weevil have not yet been found in the wild, and so the details of its life cycle are a mystery. The roots of climbing corydalis are too thin to accommodate them, and it is thought they may live inside bracken rhizomes, although searches have so far proven unsuccessful (2).

Procas granulicollis was selected as a priority species under the UK Biodiversity Action Plan (UK BAP), mainly as a result of its believed endemic status. Even though the species has now been found in Europe, the UK still holds internationally important populations, and therefore has an obligation to conserve it (2). The conservation of this weevil is co-ordinated by the Countryside Council for Wales. The Species Action Plan aims to maintain all known populations; most sites are designated Sites of Special Scientific Interest (SSSIs), or National Nature Reserves (NNRs), and therefore receive a degree of protection (3). Research is needed into the life-cycle of this weevil and into optimum management techniques of the adult food-plant, climbing corydalis (2).

This distinctive weevil is dullish black in colour. It has a dappled appearance due to the presence of patches of white hair-like bristles known as setae (2). Like all weevils, it has a prominent elongated snout (rostrum). This weevil was first discovered and described 1848, but was then considered to be a form of the similar weevil Procas armillatus. It was recognised as a distinct species in 1990 (6).

This weevil is typically found in clearings in broadleaved woodlands, where bracken (Pteridium aquilinum) grows. It has also been recorded under birch (Betula) and alder (Alnus) on a riverbank and in conifer plantations (2). In all cases, a supply of the foodplant climbing corydalis (Ceratocapnos claviculata) is required (2).

This species was, until recently, believed to be endemic to Britain (found no-where else in the world). It has, however been found in northern Spain, and it is thought that it may also occur in other countries of western Europe (2). Procas granulicollis has a scattered UK range that extends from southern England to south-western Scotland (2). It has been found in eighteen localities, and it is expected that it is more widespread than previously thought (2).

Classified as Indeterminate in Great Britain (3).

The threats currently facing this species are not known for certain (2), although clear-felling and land-use changes may be problems (4). Climbing corydalis is very prone to grazing damage, and scrub growth in clearings could create too much shade for the species (2).

In Great Britain and/or Ireland:
Foodplant / feeds on
Procas granulicollis feeds on Ceratocapnos claviculata
Remarks: Other: uncertain

Foodplant / feeds on
Procas granulicollis feeds on Pteridium aquilinum
Remarks: Other: uncertain

Wikispecies has information related to Procas granulicollis.

Procas granulicollis (sometimes known as the climbing corydalis weevil) is a beetle in the family Curculionidae, the true weevils. It was first described in 1848 from a specimen collected in Cumbria and has since been found at a number of other sites in Britain, mainly in the west. It was thought to be endemic to the island but is now also known to occur in Spain.

It is about 4-7mm long and black with white bristles giving it a mottled appearance. For many years it was considered to be a variant of the related species Procas armillatus which is very similar.

It is usually found in woodland clearings at sites where its only known foodplant climbing corydalis (Ceratocapnos claviculata) can be found. The larvae have not yet been discovered but may feed inside bracken stems.