Roesel's bush-cricket: Habitat Preferences

OrthopteraInsects
Written By Daniel Lombard

While wandering through an abandoned pasture in East Ayton, North Yorkshire, I recently encountered a good population of Roesel’s bush-cricket Roeseliana roeselii nymphs. This discovery sparked my curiosity about the specific habitat conditions that enable this species to thrive in such northern locales, far from its historical southern strongholds. Roesel’s bush-cricket has undergone a remarkable range expansion in the UK, making its presence in North Yorkshire a compelling case study. Below, I explore the species’ recent colonisation of Yorkshire, followed by a detailed examination of its habitat requirements focusing on structure, humidity, vegetation types, and broader habitat preferences, supported by scientific literature and observations from local sites, with attention to key plant species that support its populations.

Recent Range Expansion and Colonisation in Yorkshire

Historically confined to coastal saltmarshes and estuarine grasslands in southeast England, Roesel’s bush-cricket has expanded its range dramatically over recent decades, reaching as far north as North Yorkshire. The first Yorkshire record in Hull in 2015 marked a significant milestone, with populations now established as far north as Robin Hood’s Bay (Whelpdale, 2023). This northward shift is largely attributed to climate change, which has extended the growing season and increased summer temperatures, favouring the ectothermic cricket’s development and reproduction (Gardiner, 2009). The emergence of long-winged (macropterous) forms, which are more prevalent in dense populations or during warm summers, has facilitated long-distance dispersal, enabling colonisation of new sites (Gardiner, 2009). In East Ayton, the abandoned pasture likely represents such a newly colonized site, benefiting from connectivity via marginal grasslands along road verges and field edges, which have proliferated due to agricultural subsidy schemes promoting semi-natural habitats (Natural England, 2015). These corridors enhance habitat connectivity, allowing the species to exploit inland areas previously considered beyond its range.

The Roesel’s bush-cricket a rapid colonist of suitable grassy habitats in North Yorkshire following its recent establishment.

Habitat Structure Requirements

Roesel’s bush-cricket thrives in structurally complex grasslands, particularly those with tall, ungrazed swards. Optimal grass heights typically range from 30 to 80 cm, providing shelter from predators, facilitating stridulation for mate attraction, and maintaining stable microclimates (Gardiner, 2009). Short swards, often resulting from heavy grazing or frequent mowing, expose crickets to predation and environmental stressors, reducing habitat suitability (Gardiner & Hill, 2006). In contrast, the rank, uneven grassland in East Ayton’s abandoned pasture likely offers ideal conditions, with dense tussocks interspersed with patches of shorter grass or bare ground for basking and oviposition. Seasonal variations in sward height preferences are also noted, with adults favoring taller vegetation in summer (July to October) for stridulation, while nymphs, emerging in May, can tolerate slightly shorter swards during early development (Gardiner, 2009). This structural mosaic is critical for thermoregulation, as Roesel’s bush-crickets rely on external heat sources to maintain body temperature, making open, sunlit patches within tall vegetation essential (Gardiner & Hill, 2006).

Humidity Preferences

Humidity is a critical factor influencing Roesel’s bush-cricket distribution and survival, with a preference for moderately humid conditions typical of damp meadows and rough grasslands. High humidity supports egg development and nymph survival, as excessive dryness can impair embryogenesis, while overly wet conditions may increase fungal risks to eggs laid in plant stems (Hochkirch et al., 2007). Historically, the species was associated with humid coastal habitats like saltmarshes, but its inland expansion has shown adaptability to moderately moist grasslands, where poor drainage or proximity to water sources like drainage ditches, or enclosed scrub likely maintains suitable humidity levels. Research indicates that undisturbed grasslands with consistent soil moisture are preferred, as management practices like frequent mowing can reduce humidity and disrupt microclimates (Gardiner, 2009). 

Vegetation Types and Key Plant Species

The diet of Roesel’s bush-cricket, which includes grass seeds, foliage, and small insects, underscores the importance of specific vegetation types. The species shows a strong affinity for tall grass species in the Poaceae family, such as Dactylis glomerata (cock’s-foot), Festuca rubra (red fescue), and Holcus lanatus (Yorkshire fog), which are abundant in a wide diversity of improved grasslands (Gardiner & Hill, 2006). These grasses serve as both food sources and oviposition sites, with females using their ovipositors to lay eggs within stems. Unlike some orthopterans that require specialised grasses like Stipa species, Roesel’s bush-cricket is relatively adaptable, thriving in grass-dominated habitats with moderate floristic diversity (Hochkirch et al., 2007). Forbs growing within the sward provide additional food and structural complexity. Scrubby margins with species like hawthorn Crataegus monogyna or blackthorn Prunus spinosa may further enhance habitat suitability by offering shelter and microclimate stability, particularly in lowland settings (The Wildlife Trusts, 2025).

Wider Habitat Types

Roesel’s bush-cricket occupies a range of broader habitat types, reflecting its ecological versatility. Beyond its historical coastal strongholds in saltmarshes and estuarine margins, it now thrives in inland rough grasslands, damp meadows, scrub, and marginal habitats like road verges, field edges, and brownfield sites (Natural England, 2015). In Yorkshire, I have yet to find them in lowland calcareous grasslands, such as those in the Yorkshire Wolds, which may potentially e too dry to sustain this species. The abandoned pasture in which I found the nymphs in East Ayton exemplifies optimum habitat type, with its mix of tall grasses, scrub encroachment and open areas providing ideal conditions for thermoregulation and protection. Connectivity through linear features like road verges is crucial for dispersal, but habitat quality can be threatened by scrub encroachment or nutrient enrichment from agricultural runoff, which can alter vegetation structure (Gardiner, 2009). Management practices, such as light grazing or selective mowing, are recommended to maintain open, grassy conditions without compromising humidity or structural diversity (Gardiner & Hill, 2006).

Conclusion

The discovery of Roesel’s bush-cricket nymphs in a grassland at East Ayton highlights the species’ specific habitat requirements and its remarkable northward expansion in the UK. Thriving in tall, ungrazed grasslands with moderate humidity, the species relies on key grasses like Dactylis glomerata and Festuca rubra for food and oviposition, while benefiting from structurally diverse habitats like damp meadows and lowland grasslands. Its colonisation of Yorkshire, facilitated by climate change and dispersal corridors, underscores its adaptability and ecological significance. Conservation efforts should focus on preserving connected, semi-natural grasslands through targeted management to support the continued spread of this charismatic insect.

References

Daniel Lombard
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