…a blog written by Professor Karim Vahed, Buglife England Manager, as part of our COP28 impacts of climate change on invertebrates series.
The summer of 1983 sticks in my memory for one reason: it was the year that droves of Roesel’s Bush-crickets (Roeseliana roeselii) appeared suddenly in the few remaining hay meadows and neglected parks of my home town in southern Hertfordshire. As a 15 year old budding entomologist, I felt that the presence of this charismatic species, with its distinctive yellow markings and high-pitched, continuous call, was about the only redeeming feature of the town’s sprawling suburbs.
Although widespread in the rest of Europe, prior to the 1980s, the species had been restricted in the UK to a few sites in the Thames and Humber estuaries. In the early 1980s, however, it began to spread at a steady and un-relenting pace northwards and westwards. In 2014, I happened upon one in my mother-in-law’s garden in Devon, which turned out to be the first record for that county, and in 2019, I was surprised to see that new populations had appeared in the hills of Derbyshire, where I now live. Of particular note, I observed that the populations had established at relatively high altitude sites on the edge of the Peak District National Park, up to 300 m above sea level. While Roesel’s Bush-cricket is known to occur up to 2,500 m above sea level in countries such as Austria, where the continental climate results in reliably warm and dry summers, these Peak District sites were some of the highest records for the species in the UK. The species continues its northward and westward advance; in 2022, I found an adult specimen on the window ledge of the holiday cottage at which my family and I were staying in the North York Moors- one of the most Northerly records in the UK up to that point.
Roesel’s Bush-cricket is not the only one of our Orthoptera (grasshoppers, crickets and relatives) to have expanded its range in the UK. The Grasshoppers and Related Insects Recording Scheme for Britain and Ireland has been charting changes in the distribution of our species since the 1960s. It relies heavily on records submitted by the public. I submitted my records for Roesel’s Bush-cricket using the handy i-Record Grasshoppers app. The data submitted to this recording scheme show that other range-expanding species include the Long-winged Conehead (Conocephalus fuscus), the Short-winged conehead (Conocephalus dorsalis) and the Lesser Marsh Grasshopper (Chorthippus albomarginatus). In addition, several continental species have recently expanded their ranges into the UK, including the Large Cone-head (Ruspolia nitidula), the Sickle-bearing Bush-cricket (Phaneroptera falcata), the Southern Oak Bush-cricket (Meconema meridionale) and the Tree Cricket (Oecanthus pellucens).
While, as a keen fan of the Orthoptera, I welcome these additions to our fauna, I can’t help but worry about the underlying reason for range expansion. As a rule, grasshoppers, crickets and bush-crickets are warmth-loving species, requiring a warm and relatively dry spring in order to reach adulthood and mate before the end of the summer. As such, their changing distributions are a barometer for climate change. Furthermore, while there may be some winners, there will also be many losers when it comes to our changing climate. Although the ranges of some Orthoptera may be expanding, there are many more cold-adapted groups of invertebrates, such as stoneflies and bumblebees that are not predicted to fare so well.
Even within the Orthoptera, some species are doing better than others. Those species that are expanding in range tend to be habitat generalists and good dispersers. Roesel’s Bush-cricket, for example, seems to prefer rough grassland and, although the majority of individuals are short-winged and flightless, it has a long-winged form which is adept at flying and is associated with the leading edge of its range expansion. Conversely, some Orthoptera in the UK, such as the Mole cricket, (Gryllotalpa gryllotalpa), Field cricket (Gryllus campestris) and Wart-biter Bush-cricket (Decticus verrucivorus) are still so rare that they are protected by the Wildlife and Countryside Act. Such species tend to be habitat specialists and poor dispersers. For these species, it is more important than ever that we provide habitat connectivity to enable them to respond to climate change.
It is also more important than ever to keep monitoring the rapidly shifting distributions of our species by ensuring that as many people as possible submit their records to schemes such as the Grasshoppers and Related Insects Recording Scheme.