Worcestershire Record No. 16 April 2004 pp. 27-28

Geoff Trevis

Hymenoptera are under-recorded in most parts of the country, even in the south-east where species diversity is at its highest and recorders most numerous. The BRC database reveals the expected pattern for Worcestershire, despite Michael Archer’s recent important publications about the hymenoptera on Hartlebury Common and Devil’s Spittleful reserve. Of about 520 aculeate species occurring in the British Isles only 205 have been recorded in the county. These comprise 98 species of solitary bee, 22 species of social bee, 59 species of solitary wasp, 8 species of social wasp and 18 ant species. Many records date from the 1950’s and two species are now either extinct nationally or in the county, these being the bumble bees Bombus subterraneus and Bombus sylvarum (the Shrill Carder bee).

Nonetheless, records are steadily accumulating and the increasing mobility of recorders suggests that the distributions of species reflect the genuine situation rather than the distribution of the recorders. Outside the heaths in the north east of the county there are few records of notable or red data book species though investigations of sites such as the Kemerton Lakes Nature Reserve suggest that further structured recording may well turn up important finds. As is so often the case, rarer species tend to be recorded in preference to the common ones. For instance, since 1990 there have been only 20 records of the ubiquitous, white tailed bumble bee Bombus lucorum whilst, in the same period, there are 30 records of the relatively uncommon ant Lasius brunneus. A check list of county species recorded since 1990 is appended.

Dr. Michael Archer has recorded these sites at different times of year over many years and his species lists appear elsewhere in this journal, but some additional, salient features of his conclusions are summarised below.

Archer has developed a statistical analysis of data, based on the number of species on a site and the number of RDB, notable and rare species among them, leading to a quality score to compare sites. Results for Devil’s Spittleful and Hartlebury Common are shown below with results for other sites for comparison.

The Worcestershire reserves clearly occupy a position midway between these geographical extremes, as would be expected from its location, though Archer considers them to have more affinity with the southern heaths than with the northern. However, their species richness makes them of national importance.

One cautionary note made by Archer is that, based on more recent surveys, some species should be downgraded either because of range expansion or because of improved recording, and this will affect the quality scores. These species are, Philanthus triangulum, Nomada lathburiana, Priocnemis schoedtei, Andrena tibialis and Sphecodes reticulatus.

The number of ant species on the database may be increased by two due to taxonomic revisions. The common, black garden ant, Lasius niger, has now been split into two species, L. niger (ss) and L. platythorax. Similarly, Lasius alienus has also been split into two, L. alienus (ss) and L. psammophilus. These are difficult to separate morphologically and their ranges overlap. Old records will need to be reviewed and new records will only be accepted for the four species when positive identification of a voucher specimen has been made by an accredited expert.

Solitary bees