Large marsh grasshopper  (Stethophyma grossum)

Classified as Vulnerable in Great Britain.

This species is the largest grasshopper in Great Britain. It is normally vivid greenish yellow or olive brown in colour, and a purple colour form of the female sometimes occurs. The fore-wings feature a yellow stripe along the lower edge, the hind femora are marked red below and the tibia are marked with black and yellow bands.

Distributed locally across Europe (except the extreme south) from northern Spain through the former USSR to Siberia. In Great Britain it is restricted to southern England in the New Forest, Hampshire, and the Dorset heaths and is extremely local in its occurrence. Its status on the Somerset Levels and in Surrey is currently unclear.

You can view distribution information for this species at the National Biodiversity Network Gateway.

Found in wet, marshy locations, typically quaking acidic bogs in association with purple moor-grass (Molinia caerulea), bog myrtle (Myrica gale), cross-leaved heath (Erica tetralix) and white-beaked sedge (Rhynchospora alba). It was formerly known from fenland habitat, wet meadows and riverside areas.

Eggs are laid in late summer in elongate pods at the base of grasses; the nymphs emerge the following year during late May and early June. There are four nymphal stages before the adult stage is reached at the end of July. In mild weather conditions, adults may live into November. The adults are strong fliers, often covering distances of twenty metres or more. The male song consists of about eight unmistakable 'ticks' produced in 3-4 seconds; the song is produced by flicking a hind tibia against the tips of the flexed forewings. Both females and males produce this sound when alarmed or threatened.

Populations of this grasshopper in England have declined dramatically during the past fifty years, and it has been lost from many localities within its former range. This decline is largely due to the widespread drainage of wetlands and extensive peat extraction. Burning of the heathland habitat and excessive heavy grazing are also likely to be responsible for the decline of this species. In Ireland the species still seems to be abundant in western regions.

Most known sites occupied by this species are designated as Sites of Special Scientific Interest (SSSIs) or National Nature Reserves (NNRs). The UK Biodiversity Action Plan (UK BAP) has highlighted this species as a priority for conservation. The plan aims to prevent the current population size or range decreasing further, and to re-establish populations in five sites in the historic range of the species before 2010. Work to this end will be assisted by the initiation of a captive breeding programme by Bristol Zoological Gardens and English Nature.

There may be further information about this species available via the National Biodiversity Network Gateway.

The UK Biodiversity Action Plan for this species is available at UK BAP.