A fabulous family of beetles. There are only 17 species in 5 genera on the 2012 British checklist, three of which have been added since the 2008 edition of the checklist. This is a large family of beetles abroad, with many spectacular representatives, especially in warmer climates.
Possibly our most spectacular British jewel beetle is Anthaxia nitidula, only known from the New Forest and last seen there in 1954. What could have changed in the New Forest to cause the extinction of such a beetle? Apparently the final blow was over-zealous scrub clearance at Balmer Lawn in the late 1950s.
Most of the world’s jewel beetles are saproxylics and can thus be transported around the world in timber or in wooden furniture, packing materials, etc. A further nine non-native species are already listed in the 2008 checklist as “non-established introductions” and that list will probably continue to grow.
There are two genera of jewel beetles in Britain which mine leaves or stems (Trachys and Aphanisticus) and three genera of saproxylic jewel beetles (Anthaxia, Melanophila and Agrilus). The saproxylic species are very unusual amongst British saproxylic beetles. Firstly, Melanophila acuminata is our only saproxylic beetle which is strongly associated with fire-damaged wood: it is a rare and seemingly declining non-native species on lowland heathland. The six Agrilus species (and perhaps also both Anthaxia species) feed on wood at the very start of the decay process. The vast majority of saproxylic beetles cannot digest lignin or cellulose, the main constituents of wood; they can only derive nutrition from wood after fungi have begun the decay process. However, Agrilus species are able to steal a march on the fungi and feed on fresh wood, albeit they seem to be restricted to trunks or branches that are already stressed by drought, shading or physical damage. Perhaps they need bacterial decay to be underway before they can feed? If not, they must have specialist gut symbionts that can allow them to derive nutrition from lignin and/or cellulose. The only other saproxylics that can feed on living (or at least non-decaying) wood like this are many of the longhorn beetles (Cerambycidae). It is debatable whether these jewels and longhorns are saproxylic or phytophagous; beetles frequently confound attempts to categorise them and the answer here is, of course, they are both! The ambrosia bark-beetles (Scolytinae) are also pioneers of the wood-decay succession but they carry their ambrosia fungi with them to help turn living wood into food.
Finding jewel beetles is not easy. The commonest species in my experience is Agrilus laticollis though even that is Nationally Scarce (Nb). It can be beaten from the outer branches of oaks from late May to early September but particularly during June and July. The same applies to Agrilus angustulus though it is less frequent. Hawthorn Jewel Beetle Agrilus sinuatus is best recorded by looking for exit-holes in hawthorn (see my article on this species). Similarly, Agrilus biguttatus is best recorded by looking for D-shaped exit-holes in the trunks of mature oaks.
I have found Trachys subglaber and T. scrobiculatus several times by suction-sampling Devil’s-bit Scabious Succisa pratensis and Ground-ivy Glechoma hederacea respectively. See my article on Trachys subglaber (as T. troglodytes) here. Aphanisticus pusillus is also a fairly predictable species, if you target your suction-samples at Glaucous Sedge Carex flacca on calcareous grasslands in southern Britain. I have also found it by grubbing at the roots of Sand Sedge Carex arenaria in the Brecks. In the tray, these are all beetles which tuck their legs and antennae in and lie still for a long time; it’s easy to overlook them as just seeds.
With the recent growth in use of suction-samplers, records of all three of these species must have increased dramatically. So it is surprising that nobody has yet found Aphanisticus emarginatus by suction-sampling. It hasn’t been seen in Britain since 1951 (Longmoor Camp, Liphook, North Hampshire). Other old records come from North Devon, Dorset, the Isle of Wight (Parkhurst) and Berkshire. Target Jointed Rush Juncus articulatus if you want to be the one to rediscover it. It is a more slender, elongate species than A. pusillus.
Trachys minuta is another rare species. Its larvae develop on willows/ sallows Salix spp. and Hornbeam Carpinus betulus (according to Levey (1977)). Adults are best found by beating the branches and foliage of these hosts, although David Appleton found it repeatedly and in numbers on hazel branches at Botley Wood, Hampshire (Appleton, 2004).
Brian Levey (2012) added Trachys subglaber to the British list, a very similar species to Trachys troglodytes. Both subglaber and troglodytes are long-established British species but subglaber has been unrecognised and records of both species have been effectively lumped under the name troglodytes. T. subglaber is the commoner and more widespread species in Britain, mining Devil’s-bit Scabious Succisa pratensis and probably only this plant. T. troglodytes in the narrow, post-Levey (2012) sense appears to be more of a Suffolk Breckland specialist, also with a couple of Kent records, and probably mining Field Scabious Knautia arvensis in its British localities.
Until recently, I would have started with Brian Levey’s (1977) Royal Entomological Society Handbook (out of print). Since Levey’s Handbook, four species have been added to the British list:
Bílý (1982) is the English-language key which best covers the British fauna (excluding only Agrilus sinuatus) but the papers by Trevor James and Peter Hodge are also invaluable for identification of Agrilus. Brian Levey is drafting a new key to the enlarged British fauna of eight Agrilus species which I look forward to seeing. Meanwhile, for anyone who can read French, all the British species of Agrilus are covered by Théry’s (1942) Faune de France volume which can be downloaded for free. Bílý (1982) and Théry (1942) both include A. cuprescens under the name A. aurichalceus but otherwise the names agree with the Duff (2012) checklist.
More recently, I have bought a copy of Oscar Vorst’s (2009) excellent handbook on the Buprestidae of the Netherlands. Inconveniently, it is in Dutch but does include an English-language version of the key as an Appendix. And the distribution maps, phenology charts, photographs and line drawings are at least accessible to anyone. I still haven’t really put these keys to the test but they look excellent.
More recently still, Mike Hackston has combined the keys from Levey’s (1977) RES Handbook with a translation of Théry’s (1942) Faune de France keys, as well as adding in the latest addition to the British list (Trachys subglaber) and placed the collated keys online here.
Distribution Atlas and Recording Scheme
There are distribution maps and species accounts in the provisional atlas (Alexander, 2003) (except Anthaxia quadripunctata, Agrilus cuprescens and Agrilus cyanescens). Order from the BRC website. Keith Alexander would be glad to receive records of jewel beetles for the national Cantharoidea & Buprestoidea Recording Scheme: details here.
Thanks to Keith Alexander for comments and advice on this webpage.
Alexander, K.N.A. (2003). Provisional atlas of the Cantharoidea and Buprestoidea (Coleoptera) of Britain and Ireland. Huntingdon: Biological Records Centre.
Appleton, D. (2004). Scarcer Coleoptera in Hampshire and Isle of Wight 1964 – 2001. The Coleopterist, 13: 41 – 80.
Bílý, S. (1982). The Buprestidae (Coleoptera) of Fennoscandia and Denmark. Fauna entomologica scandinavica, vol. 10. Klampenborg: Scandinavian Science Press.
Cooter, J. (1992). Anthaxia quadripunctata (Linnaeus, 1758) (Coleoptera: Buprestidae) in England: an enigma. Entomologist’s Gazette, 43: 75.
Hodge, P.J. (2010). Agrilus cuprescens (Ménétriés, 1832) and A. cyanescens Ratzeburg, 1837 (Buprestidae) established in Britain. The Coleopterist, 18: 85 – 88.
James, T.J. (1994). Agrilus sulcicollis Lacordaire (Buprestidae): a jewel beetle new to Britain. The Coleopterist, 3: 33 – 35.
Levey, B. (1977). Coleoptera: Buprestidae. Handbooks for the identification of British insects, vol. 5, part 1 (b). London: Royal Entomological Society.
Levey, B. (2012). Trachys subglaber Rey, 1891 (Buprestidae) an unrecognised British species. The Coleopterist, 21, 67 – 72.
Théry, A. (1942). Coléoptères buprestides. Faune de France, 41. Paris: Librairie de la Faculte des Sciences. [available for download from here]
Vorst, O. (2009). De Nederlandse prachtkevers (Buprestidae). Entomologische Tabellen 4. Supplement bij Nederlandse Faunistische Mededelingen. Leiden: Nederlandse Entomologische Vereniging.