Field cricket (Gryllus campestris)
|Size||Female length: 17 - 22 mm|
Ovipositor length: 8 - 12 mm
Male length: 19 - 23 mm
Classified as Endangered in the UK.
The field cricket is an impressive insect with a black body and wings that resemble intricate wrought iron work. The wing colour is dark black/brown, with a yellow base and black raised veins. A modified area of veins on the male's wings, known as the 'harp', enables it to produce the 'song' or stridulation that he uses to attract a female.
Most of Europe except in the north. It has never been common in the UK and most of its historical sites have now disappeared. By the 1980s, the field cricket's UK range was limited to one site in West Sussex.
Field crickets need close-cropped turf on warm, dry, porous soil. The sites should be sheltered and in full sun.
Gilbert White, in his book 'The natural history of Selbourne', describes how field crickets could be lured out of their burrows by the insertion of a twig or grass stalk. White studied the cricket in some detail and observed that the males clear a small platform in front of their burrows from which they broadcast their 'love songs'. Field crickets are flightless, and the females locate singing males by crawling across the ground to them. After mating, either inside or outside the burrow, the female lays her eggs in areas of disturbed soil in full sunlight. Young cricket nymphs hatch in July and August, and grow rapidly. In early autumn a hibernation burrow is dug and the nymph spends the winter here.
Although never more than locally common, the field cricket has declined through loss of habitat. The Hampshire site where Gilbert White conducted his research is now covered by a mature beech wood. Another lies buried under an oil refinery and many others have been turned over to agriculture or forestry.
Because of its endangered status the field cricket was included in English Nature's Species Recovery Project (SRP) in 1991. Initial work concentrated on ascertaining the status of the only UK population, determining habitat requirements and provision of advice on habitat management. The next step was to initiate a captive breeding programme. The Invertebrate Conservation Centre based at London Zoo obtained a number of adults in 1991 and began to establish a viable breeding population. On the ground, preparations were made to restore some of the crickets' former sites back to suitable condition ready for release of the captive-bred stock. This re-introduction began the following year, appropriately, near Arundel Castle Cricket Ground. Since then re-introductions have continued and some have been the subject of keen media interest with a BBC documentary following the progress of the captive crickets at London Zoo.
Information supplied and authenticated by Bryan Pinchen (independent ecologist).
- Hibernation: a winter survival strategy characteristic of some mammals in which an animal's metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is 'diapause', a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
- Nymphs: stage of insect development, similar in appearance to the adult but sexually immature.