The Gilkicker Weevil

©Jack Hawnt

Description, ecology and monitoring of an endangered species of weevil secluded to the south-coast

Gilkicker Weevils Pachytychius haematocephalus

The Gilkicker weevil Pachytchius haematocephalus is an endangered species of weevil that is now only found near Gosport at Gilkicker Fort, Stokes Bay Promenade and Browndown ranges for reasons that are relatively unknown. This isolated community makes up many small un-connected colonies along the 5km stretch of coastline.

Records show that colonies were originally found at Charmouth, Dorset with the last specimen being found in 1947. Although recent surveying has shown this species is no longer present in Dorset and therefore extinct in the county. Throughout Europe however populations of the species are found mainly on the Mediterranean coast, northern France and the channel.

In Britain the Gilkicker weevil is classified as a Red Data Book 1-Endangered species, and as a result is listed as a priority in the UK Biodiversity Action Plan, which details proposals to conserve and enhance the Gilkicker weevil for which the Wildlife Trusts are lead partners for the SAP (Species Action Plan).

Description

Adults are small, 3-4 mm long with a distinctive red rostrum and a black or reddish-black body covered in grey and/or yellowish scales. The species has a distinctive shape compared to other weevils, it has a fairly long snout (rostrum), has parallel sides; a wide, rounded thorax; and thick legs. 

Gilkicker weevils found on a survey

©Jack Hawnt

Ecology

In terms of ecology of the Gilcker weevil information is relatively limited. The host plant is known to be Bird's-foot-Trefoil Lotus corniculatus, in which eggs are laid in the pods of the Lotus so that the larvae can then feed on the un-ripened seeds in the summer; although the adults feeding plant is unknown. As an adult the weevil will over-winter, site selection for this is unknown, however due to the construct of the adult weevils body in being tubular with stout strong legs it is thought to be believed that they are a burrowing species.     

Despite Bird's-foot-Trefoil being a common plant, the Gilkicker weevil is only found on the coast, indicating the ecological preferences of the species are specific. The preferred habitat is partially vegetated, exposed coastal grassland and shingle. The species requires hot, frost free micro-climates.

Adults are active from February to June, with peak activity in mid-June. Previous adult surveys found no active adults after August. 

Promenade at Gosport, showing Gilkicker Weevil habitat

 ©Jack Hawnt

Monitoring

The most recent monitoring surveys of Gilkicker weevils at Browndown, Stokes Bay Promenade and Gilkicker Heritage Area have been led by Trainee Ecologist Jack Hawnt of Hampshire & Isle of Wight Wildlife Trust.

The aim of this survey was to determine the ongoing presence of Gilkicker weevils at each of the sites. The surveys were continuing population monitoring conducted in 2002 and 2018. 

The survey method uses a reversed leaf blower with a fabric mesh that safely captures the weevils so that they can then be sorted in a tray. 

Record numbers of the species have been found this year, with the report currently being written; which should be published shortly.  

 

 

The modified leaf blower being used to survey for Gilkicker Weevils

Agatha Thompson - Gilkicker Weevil survey ©Jack Hawnt