Mole cricket (Gryllotalpa gryllotalpa)
|Size||Body length (males): 35-41 mm|
Body length (females): 40-46 mm
Classified as Endangered in the UK, and protected under Schedule 5 of the Wildlife and Countryside Act 1981. There have been only four confirmed records of the mole cricket in Great Britain between 1970 and 2001.
This is our largest native orthopteran and one of our most impressive and unusual looking insects. The scientific name derives from the Latin 'gryllus' meaning cricket and 'talpa', mole, and refers to its similarity to a mole in both looks and subterranean habits. The body is brown in colour and covered with fine velvety hairs, and the forelegs are greatly modified for digging. Only the adult stages are winged, and flight is said to be clumsy, directionless and only performed on rare occasions at night. Males can be distinguished from the females by the open vein area in the forewing known as the 'harp', females lack the external ovipositor of other crickets.
The mole cricket occurs throughout Europe, except Norway and Finland, through to western Asia and North Africa. Historically in Great Britain it has been recorded from most counties. Recent records have come from Dorset, Bedfordshire, Cheshire and Essex. There are still strong populations in Guernsey, Channel Islands.
Ideal habitat appears to be short, thin swards on sandy loam or peaty soils with a fluctuating water table or seepage line and areas of disturbed or cultivated ground.
Eggs are laid in underground chambers from early spring to the end of July. These are tended by the female until they hatch two to four weeks later. Nymphs begin to mature from the following spring onwards; but some may not mature until their third spring. Adults and nymphs can be found throughout the year in extensive tunnel systems that may reach a depth of over one metre. Mole crickets are omnivorous, feeding on a range of soil invertebrates and plant roots; often leaving neat circular holes through the roots of tuberous plants. Males occasionally produce a soft, but far-carrying 'churring' song from within a specially constructed chamber in the burrow system, which acts as an amplifier for the song, which is likely to be used for attracting females. The song is typically produced on warm balmy evenings in early spring between dusk and dawn, and it is similar to the song of the nightjar Caprimulgus europeaeus.
Once widespread throughout Great Britain, the mole cricket may now be close to extinction. Reasons for this dramatic decline include changes in agricultural practices and the widespread use of pesticides, drainage of wetlands and reduction of grazing or conversion to silage on damp meadows. Sites in Surrey and Hampshire were destroyed through building development.
The mole cricket was identified as a priority for conservation under the UK Biodiversity Action Plan (UK BAP). The Action Plan aims to establish 20 self-sustaining populations in the former range by 2005 and establish breeding colonies in captivity. Work as part of the English Nature Species Recovery Programme has appealed for the public to report sightings of the mole cricket, and a captive rearing programme has been in operation since 1996. The Natural History Museum is the lead partner for the conservation of this species, with English Nature. If you see a mole cricket in the UK please contact the Mole Cricket Working Group at the address below. Please provide the following information: Circumstances of the discovery, time of year, location of sighting, habitat present and what has happened to the insect now; if possible take a photograph for confirmation of the record.
Information supplied and authenticated by Bryan Pinchen (independent ecologist). Bryan Pinchen, Co-ordinator, Mole Cricket Working Group. 7 Brookland Close, Pennington, Lymington, Hampshire. SO41 8JE. Email: firstname.lastname@example.org
- Orthopteran: member of the group of insects comprising crickets, grasshoppers and locusts. They typically have large hind-legs modified for jumping.
- Ovipositor: egg-laying organ in female insects consisting of outgrowths of the abdomen (the hind region of the body in insects). The stinging organ and poison sac of worker bees and non-reproductive female wasps is a modified ovipositor.