Ground beetle (Bembidion testaceum)
|Also known as:||river shingle beetle|
|Size||Adult length: 4.5-5.5 mm (1).|
Classified as Nationally Scarce in Great Britain (2).
Bembidion testaceum is a predatory ground beetle that is very similar in appearances to other related Bembidion species (2). This is a genus of small beetles that often have markings on the wing cases (elytra). This species has a dark head and pronotum with a greenish reflection, and the wing cases are reddish brown with hardly a trace of discrete reddish spots (3).
Although this species is easily confused with other members of the genus and old records may not be reliable, it is clear that Bembidion testaceum once had a wide, yet scattered distribution in England and Wales, reaching up into southern Scotland. This beetle has undergone a decline, however, and is now known only from 4 areas. Two of these occur in northern England, with one in south Wales and the fourth on the Welsh Borders (2). In the rest of Europe, this beetle has a wide range; Britain represents the north western limit of this distribution (2).
This species is known as a river shingle beetle, as it is found amongst sand and gravel beside slow-flowing or still water (2).
Very little is known of the biology of this predatory species. It is able to fly, and breeds in spring and early summer (3).
The habitat of this species is likely to be damaged by a range of factors, including river straightening and dredging, control of river flow rate caused by damming or flood reduction schemes, trampling by livestock, and the spread of the invasive plant Himalayan balsam (Impatiens glandulifera) (2).
A number of beetles sharing this river shingle habitat have been highlighted as priorities under the UK Biodiversity Action Plan (UK BAP). A Group Action Plan has been produced to coordinate efforts to conserve these species. This plan aims to maintain current populations. The Environment Agency, English Nature and the Countryside Council for Wales have joint-funded studies aiming to improve understanding of these species, in order to better guide their conservation (2).
Information authenticated by Dr Martin Luff of the School of Biology, University of Newcastle, with the support of the British Ecological Society:
- Genus: a category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
- Pronotum: in insects, the hardened cuticle on the upper surface of the first thoracic segment (the part of the body nearest the head).
- Thorax: part of the body located near the head in animals. In insects, the three segments between the head and the abdomen, each of which has a pair of legs.