WART-BITER

Decticus verrucivorus 

Decticus verrucivorus - Wart-biter.jpg

A large dark green cricket with visible dark blotches on the upper body.

  • Rarity: In Great Britain it is extremely localised and restricted to southern England where just five populations are now known.

  • Cause of decline:The animals require a complex mixture of bare ground and long and short turf – either on chalk downland or heathland. Both these habitats, and the forms of management which produce these specific conditions have declined, along with several insects that rely on them.

The Wart-biter Bush-cricket was once used exactly as the name suggests, as a method for removing warts. The cricket would be placed next to the affected area and it would slowly attempt to chew off the wart. This method is in fact ineffective, but was widely practised nevertheless.

Sadly, if we wanted to try this today, we would be seriously constrained by the incredible rarity of the species. It is now found at only six sites in the UK, and in relatively low numbers at each of these sites, which makes it highly vulnerable to extinction. The cricket also has very specific habitat requirements which make it vulnerable to any deterioration in habitat quality.

Wart-biter survey 2015

Surveys conducted in 2015 suggested that Lydden Temple Ewell NNR supported a population of around 100 D. verrucivorus during the early adult period. A review of the status of the species since its re-introduction to the site between 1993 and 1996 puts this result into context. The population size in 2015 was broadly consistent with the numbers that the site (or compartment Ly1, specifically) was expected to support when the reintroduction was being planned, i.e. a “cautious” estimate of 90 adults in an average year. It is also broadly consistent with numbers recorded annually since the re-introduction. 

Although data are limited or unavailable for some years, the early adult population appears most often to have been in a range of around 50-200. However, numbers have varied beyond this range, reaching a peak of around 450 in 2001 and 2002, but falling to a very low level in 2003, when favourable habitat structure failed to develop over most of the area occupied by the species, and again in 2005.