The Wart-biter cricket (Decticus verrucivorus) is a large bush-cricket in the family Tettigoniidae. Adults measure between 31 and 37mm and the ovipositor (egg-laying organ) of the females can measure up to 21mm. It has large, dark eyes and is typically dark green, often with dark brown or black blotches on the body and wings. Its large and powerful hind legs give this species a frog-like appearance. Like all crickets, the Wart-biter cricket ‘sings’ by rubbing its wings together (grasshoppers sing by rubbing their long legs against their wings). Its fairly loud and distinctive song consists of a series of rapidly repeated clicks in short bursts and often lasts for several minutes. Despite having wings, the Wart-biter cricket is usually flightless, although it has been known to fly up to 3 or 4 metres when frightened.
 (c) Mats Carnmarker small.jpg) |
| Wart-biter cricket (Decticus verrucivorus) © Mats Carnmarker |
See the Wart-biter cricket in action!
This intriguing short video by Dr. Simon Robinson, senior keeper at London Zoo, shows the Wart-biter chewing away at a wart on his finger.
A cure for warts?
The Wart-biter cricket derives its name from the age-old practice by Swedish peasants of using the cricket to bite warts from the skin. Its Latin name Decticus verrucivorus, given by the Swedish naturalist Linnaeus, comes from the Latin ‘verruca’ meaning ‘wart’, and ‘vorous’ meaning ‘to devour’. For those readers hoping for a novel cure for their pesky warts, you may be disappointed to learn that it appears that this treatment is not particularly effective!
Unsurprisingly enough, warts are not a big part of this cricket’s diet. The Wart-biter is omnivorous, feeding on a range of herbs and insects, including other grasshoppers.
Life cycle of a Wart-biter
Wart-biter crickets are elusive creatures. The adults are active mainly during the day and males only sing during hot, sunny and still weather. Adults lay single eggs in bare soil close to clumps of grass and these remain dormant for at least two years before eventually hatching in mid-Spring. Several nymphal (immature) stages are passed before the adult stage is reached at the beginning of July. Most adults only survive until September. To provide the right conditions throughout its lifecycle, the Wart-biter cricket requires a mosaic of vegetation structures including bare ground and short turf for egg-laying and early nymphal stages, while taller tussocks of grasses and flowering plants are required for the larger nymphs and adults. Sunny, well-sheltered calcareous grasslands can provide this mosaic and this is typically where Wart-biter crickets can be found, although one population in Britain inhabits rough heathland adjacent to improved grassland.
 Harold Supfle .jpg) |
| A female Wart-biter cricket (Decticus verrucivorus) © Harold Supfle |
On the edge
The Wart-biter is found throughout Europe, except in the extreme south, and in temperate Asia as far east as China. The species has been in Britain for more than 10,000 years and is thought to have been rare since at least the early 1800s. Unfortunately, environmental changes due to unsuitable grazing systems and other destruction of grassland habitats have caused a significant decline of D. verrucivorus crickets. Now just five small populations in southern England remain, one of which resulted from a reintroduction. Although the species is more common in Europe, numbers are also declining due to changes in agricultural practices.
This fascinating species is considered one of Britain’s most endangered insects and it continues to face the threat of extinction from unsuitable site management and also from predation by birds. Thankfully, the Wart-biter cricket is protected under the Wildlife and Countryside Act 1981 and the UK Biodiversity Action Plan (UKBAP). It is also listed as Vulnerable in the Red Data Book. London Zoo, in partnership with Natural England’s Species Recovery Programme, has been working to save this beautiful cricket from oblivion. The species has been bred in captivity and some of these were successfully reintroduced into restored habitat at former Wart-biter sites in Kent. Further reintroductions are likely to happen in the future, giving hope for the survival of the wonderful Wart-biter.
Find out about the vital conservation work carried out by London Zoo.
Find out more about the crickets and grasshoppers of Britain and get involved with recording these fascinating creatures with the Orthoptera Recording Scheme.
