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The Fauna Of Tunbridge Wells And Rusthall Commons - Part 9

Rove beetles, characterized by their short wing cases exposing most of the abdomen, are abundant inhabitants of the Commons, although most species are small and do not attract attention. Only the large black Staphylinus olens, the so-called Devil’s Coach-horse, is likely to be noticed by the general public running over sunlit footpaths. Click beetles, slender insects so called because of their ability to flip themselves into the correct position after falling on their back, are also numerous, and the common Athous haemorrhoidalis actively flies by day. The large mottled Agrypnus murinus is another notable member of the same family. Members of the scarab group found on the Commons include the familiar Cockchafer or May-bug (Melolontha melolontha), which is nocturnal and attracted to light, the Minotaur Beetle (Typhaeus typhoeus), a dung-beetle with three horns in the male, and the Lesser Stag Beetle (Dorcus parallelipipedus).

The extensive order Hemiptera is divided into two sections, the true bugs or Heteroptera and the aphids, leafhoppers, froghoppers and related forms of the sub-order Homoptera. An often overlooked group of insects, many species are found in grassland and woodland on the Commons. The Homoptera are mostly small insects which attract little attention, although the nymphs of froghoppers make themselves conspicuous by producing protective ‘cuckoo spit’, and some aphids feed in large clusters which are attended by ants in search of honeydew. Some of the larger and more colourful leafhoppers may also be noticed by the non-specialist, for example the bright green Cicadella viridis which frequents the damp grassland around ponds. Among the largest of the true bugs found on the Commons are the shieldbugs, including the common Green Shieldbug (Palomena prasina), often seen on bramble foliage, and the attractive green and purple Hawthorn (Acanthosoma haemorrhoidale) and Birch (Elasmostethus interstinctus) Shieldbug. The large brown squashbug Coreus marginatus is also easy to spot, as it sits openly on dock leaves. Aquatic members of the Heteroptera include the backswimmer Notonecta glauca and the familiar pond-skaters (Gerris spp.), which live on the surface film of ponds.

The ponds on the Commons also support various species of mayflies, stoneflies and caddis-flies. The larvae of the latter are well-known for the protective cases they construct out of plant material or other debris gathered from their watery habitat, but the adults, if noticed at all, are likely to be mistaken for moths. These three groups are among the smaller insect orders, as are the lacewings, which are predatory on aphids in both adult and larval stages. Those most likely to be noted on the Commons are the delicate green species of the genus Chrysopa. A related group are the scorpion-flies, often seen fluttering among brambles or nettles. Despite the curious scorpion-like tail of the male, they are harmless scavengers.

In conclusion, brief mention should be made of invertebrate groups other than insects. On the Commons, the spiders are the most conspicuous of these, representing a variety of lifestyles. Spiders are most popularly associated with the building of webs, the most elaborate being those constructed by the orb weavers such as the large and familiar Araneus diadematus or the smaller bright green Araniella cucurbitina. Many species, however, actively hunt their prey. These include the jumping spiders (Salticidae), often seen on sunlit rocks, the fast running wolf spiders (Lycosidae) which may be seen in large numbers on open ground, the females carrying their silken egg-sacks, and impressive white-banded Pisaura mirabilis, which is generally seen perched conspicuously on foliage. The white or yellow crab spider Misumena vatia sits on flowers waiting to pounce on visiting insects. Centipedes, millipedes and woodlice generally keep themselves out of sight under stones or fallen timber, although the shiny black cylindrical millipede Tachypodoiulus niger sometimes makes its presence more obvious by climbing the trunks of trees. The Pill Millipede (Glomeris marginata) defends itself by rolling into a ball, as does the superficially similar Pill Woodlouse (Armadillidium vulgare). Unlike the slower millipedes, centipedes are fast moving predators, the most distinctive species on the Commons being Lithobius variegatus with purple bands on its legs and similarly coloured marks on its body. Molluscs too are a significant element in the Commons’ fauna, both in the various ponds and on land. The most attractive of the terrestrial snails is the highly variable Cepaea hortensis, whose brightly coloured or banded shells are often seen in fragmentary form around the ‘anvils’ of the Song Thrush.

Page last updated: 18/12/2012