Wart-biter

The wart-biter (Decticus verrucivorus)[1] is a bush-cricket in the family Tettigoniidae. Its common and scientific names derive from the eighteenth-century Swedish practice of allowing the crickets to nibble at warts to remove them.[2]

Wart-biter
Adult female of the green morph
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Orthoptera
Suborder: Ensifera
Family: Tettigoniidae
Subfamily: Tettigoniinae
Tribe: Decticini
Genus: Decticus
Species:
D. verrucivorus
Binomial name
Decticus verrucivorus

Description

Adult wart-biters are 31–37 millimetres (1.2–1.5 in), with females being significantly larger than males. They are typically dark green in colour, usually with dark brown blotches on the pronotum and wings (a dark brown morphotype also occurs). The female has a long and slightly upcurved ovipositor.[3]

The wart-biter has a song consisting of a rapidly repeated series of short bursts of clicks, sometimes lasting for several minutes.

Wart-biters normally move about by walking; they rarely fly, except when frightened. Most can only fly 3 to 4 metres (10 to 13 ft) at a time.

Subspecies

The Orthoptera Species File[4] lists:

  • D. verrucivorus assiduus Ingrisch, Willemse & Heller, 1992
  • D. verrucivorus brevipennis Götz, 1970
  • D. verrucivorus crassus Götz, 1970
  • D. verrucivorus gracilis Uvarov, 1930
  • D. verrucivorus longipennis Nedelkov, 1907
  • D. verrucivorus mithati Ramme, 1939
  • D. verrucivorus monspeliensis Rambur, 1838
  • D. verrucivorus stoljarovi Götz, 1970
  • D. verrucivorus verrucivorus (Linnaeus, 1758) - nominate subspecies, to which the 'wart-biter' belongs.

Habitat

The species is found in calcareous grassland and heathland habitats.[3]

Wart-biters need a mosaic of vegetation, including bare ground/short turf, grass tussocks, and a sward rich in flowering forbs. They prefer areas that are not heavily grazed. The species is thermophilous, and tends to occur on sites with a southerly aspect.[5]

Diet

The species is omnivorous. Plants eaten include knapweed, nettles, bedstraws; the species also eats insects, including other grasshoppers.

Life cycle

The wart-biter lays its eggs in the soil; these eggs normally hatch after two winters. It then passes through seven instar stages between April and June. The adult stage is reached in the beginning of July. Wart-biter populations peak in late July and early August.[3] Newly hatched Decticus are encased in a sheath to facilitate their trip to the soil surface, the sheath holding the legs and antennae safely against the body while burrowing upwards. A neck which can in turn be inflated and deflated, enlarges the top of its tunnel, easing its passage upwards.[6]

Status and distribution

This species occurs throughout continental Europe, except the extreme south, ranging from southern Scandinavia to Spain, Italy, and Greece. It is also found in temperate Asia, as far east as China. Geographic features such as mountains have fragmented the species, leading to a wide range of forms and numerous subspecies.[7]

In Britain, the wart-biter is confined to five sites, two in East Sussex, and one each in Wiltshire, Essex, Dorset and Kent.[3]

Conservation

The population of wart-biters has declined in many areas of northern Europe. In Britain, it is threatened with extirpation.[8] The species is the subject of a United Kingdom Biodiversity Action Plan.[9]

References
  1. "Wart-biter bush-cricket | Buglife". www.buglife.org.uk.
  2. "Rare wart-biter cricket's powers put to the test". BBC News. Retrieved 9 August 2020.
  3. Judith A. Marshall & E. C. M. Hayes (1988). Grasshopper and allied insects of Great Britain and Ireland. Harley Books. ISBN 0-946589-36-4.
  4. Orthoptera Species File: species Decticus verrucivorus (Linnaeus, 1758) (Version 5.0/5.0 retrieved 30 May 2020)
  5. Dag Øystein Hjermann & Rolf Anker Ims (1996). "Landscape ecology of the wart-biter Decticus verrucivorus in a patchy landscape". Journal of Animal Ecology. British Ecological Society. 65 (6): 768–780. doi:10.2307/5675. JSTOR 5675.
  6. Jean-Henri Fabre - "Book of Insects"
  7. M. J. Samways & K. Harz (1982). "Biogeography of intraspecific morphological variation in the bush crickets Decticus verrucivorus (L.) and D. albifrons (F.) (Orthoptera: Tettigoniidae)". Journal of Biogeography. Blackwell Publishing. 9 (3): 243–254. doi:10.2307/2844667. JSTOR 2844667.
  8. Andrew A. Cunningham; J. Mick Frank; Pat Croft; Dave Clarke & Paul Pearce-Kelly (1997). "Mortality of captive British wartbiter crickets: implications for reintroduction programs" (PDF). Journal of Wildlife Diseases. 33 (3): 673–676. doi:10.7589/0090-3558-33.3.673. PMID 9249724.
  9. "United Kingdom Biodiversity Action Plan for the Wart-biter". Archived from the original on 2006-06-21. Retrieved 2006-07-22.
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