Evidence from the latest study into the conservation status of Britain’s grasshoppers, crickets and allied species reveals an “extraordinary change in the fortunes” of many species of these insects since 1997.
The new publication from the UK’s Species Status Project – A review of the Orthoptera (grasshoppers and crickets) and allied species of Great Britain – charts the fortunes of a fascinating but little known group of insects, that are more often heard than seen. It has been published by Natural England in collaboration with the invertebrate conservation charity, Buglife.
These species of invertebrates are considered important indicators of the state of the natural environment. Many species are showing signs of range change in response to climatic change. They are also often highly specialised in their habitat requirements and are useful indicators of changes in habitat quality. Insects are also the essential foundation of many food chains and are vital to healthy ecosystems.
The review has revealed that some once rare species have become considerably more widespread and abundant; while other species have declined dramatically in their former strongholds. Targeted conservation action supported by both Natural England and the voluntary sector is underway to try to prevent further declines in the rarest species.
Natural England project manager, Jon Curson, said: “Invertebrates are integral to our natural environment, fundamental to the food chain and excellent indicators of the health of our natural habitats. Natural England supports the production of this kind of review to help share our data and improve the understanding of our rarest species and how best to conserve them and the habitats they live in for the future.”
Sarah Henshall, Lead Ecologist at Buglife, said: “Orthoptera contains some of our most charismatic and spectacular species, from the impressive Wart-biter bush-cricket to the elusive Mole cricket. They are a valuable indicator of the state of our environment, responding to changes in habitat quality and climate. The review highlights the importance of recording and conservation efforts undertaken by Buglife and other organisations.”
The review highlights how carefully targeted species re-introduction programmes have been a vital lifeline for the wart-biter cricket (Decticus verrucivorus) and field cricket (Gryllus campestris). New populations of both species have been established in southern England, thanks to partnership work with local famers and other land managers. There is also some encouraging news for the once widespread mole cricket (Gryllotalpa grylloptalpa), which was thought to be extinct in Britain until a small population was discovered in Hampshire in 2014, although it is currently unclear whether any were recorded this year.
The new review documents the appearance of three species new to Britain that have appeared as colonists, or potential colonists, on the back of northward European range expansions; and highlights the spectacular range expansions of species like the Long-winged Conehead (Conocephalus discolor) and Roesel’s Bush-cricket (Metrioptera roeselii).
The review includes detailed data sheets that are being made available for the first time, to help focus resources on managing habitats in the best way to improve the conservation status of these insects.
The report is the latest in a series to be made available as part of the Species Status Project, which is publishing evidence-based reports that will help conservation organisations to target future action. The species status project is a new initiative that provides up-to-date assessments of the conservation status of various species of insects using the internationally accepted guidelines developed by the International Union for Conservation of Nature (IUCN)
The review can be downloaded from the Natural England’s publications catalogue:
NECR187 – A review of the Orthoptera (grasshoppers and crickets) and allied species of Great Britain
Case studies:
Wart-biter bush-cricket (Decticus verrucivorus)
The wart-biter bush-cricket – which gets its name from the ancient Swedish medical practice of using the insects to eat skin warts – was once found across southern England. The bush-cricket, which can grow up to 2 inches in length, has very exacting habitat requirements and requires a particular kind of grassland habitat that includes bare ground, short turf and taller clumps of grass.
Wart-biter numbers have declined dramatically as a result of loss of suitable grassland and unsuitable grazing regimes. The bush-cricket is now found at only five locations in Britain (three with native populations and two reintroduction sites). A captive breeding programme involving London Zoo, Natural England, Buglife and a partnership of environmental groups, landowners and farmers, has seen the wart-biter reintroduced at two sites in southern England. In addition, a translocation of wart-biters to a site in E. Sussex where it had recently gone extinct was started in 2015. Monitoring over next few years will confirm whether this project has been successful in providing a long-term lifeline to this rare insect.
The new review classifies the wart-biter as an ‘endangered’ species in Britain.
Field cricket (Gryllus campestris)
Before re-introductions were undertaken as part of Natural England’s Species Recovery Programme, the field cricket (Gryllus campestris) was found at only a single colony in West Sussex. There are now six re-introduced populations in four counties. Several of these re-introductions are very recent and it’s not yet known how sustainable they will be in the long-term. The current review suggest that although still classified as ‘vulnerable’ the species is spreading in at least two of the sites, with more re-introductions planned in the future.
Mole cricket (Gryllotalpa gryllotalpa)
With only one small and recently discovered colony currently known, the species is classified as ‘critically endangered’. Mole crickets live in wet soils in water meadows and wet heathlands and before the extensive land drainage that occurred in the 17th and 18th centuries the mole cricket was found widely in Britain. The species was thought to be possibly extinct in Britain until a small population was discovered in the New Forest in 2014. Although the situation remains critical for this subterranean cricket, it appears to be still clinging on in one part of Britain and future management will involve monitoring the colony and maintaining suitable habitat.
Long-winged conehead (Conocephalus discolor)
Conocephalus discolor is quite widespread in southern and central Europe, and is spreading northwards. The species was first discovered in Britain in the 1940s and was only found around the south coast of England. In the 1980s there was dramatic population growth and the range of this bush-cricket expanded more than 150 miles in 20 years. Now the long-winged conehead can be found in many parts of the country beyond the River Thames, as far north as Humberside and as far west as Wales. The review suggests that the shift in the bush cricket’s distribution has occurred in response to climate change.
