centipedes,millipedes

Lithobius forficatus (20-30 mm) Lithobiidae Shiny reddish-brown with 15 pairs of legs. Active hunter preying on small insects, worms, slugs and other centipedes. The young possess 7 pairs of legs after hatching from the egg, gaining an additional pair after each moult until adulthood. Ubiquitous, particularly common in gardens. Image taken at Martin Down, near Salisbury, Wiltshire .

Elongated flattened predatory arthropods with each body segment containing one pair of legs. The hind legs are elongated and act as sensors. The front of the head possesses a pair of poisonous fangs. Feed on worms, insects and their larvae. May bite man, but none of the UK species are dangerous. Nocturnal, hiding beneath stones, fallen logs and leaves or hidden in the soil during the day. There are five orders, the first four containing 'running' centipedes, the final order containing those that 'crawl' - Scolopendromorpha (3 UK species), Lithobiomorpha (20 UK species), Scutigeromorpha (1 UK species), Craterostigmomorpha (no species in the UK) and Geophilomorpha (30 UK species). Geophilids are blind and live in the crevices between soil particles.

The gonads lie at the rear of the centipede, the male transferring a sperm packet known as the spermatophore to the female. Around 30-40 eggs are laid with care varying between species. The larvae undergo a number of moults, in the case of lithobids newly hatched larvae have four pairs of legs that get added to with each moult until the adult complement of 15 pairs is reached.

In defence the poison claws may be used, although in the UK species these are not very painful to humans. Lithobids can secrete a repellant from the rear legs to repel predators. Geophilids can secrete a sticky glue-like chemical from glands located centrally on the side of each segment.

Geophilus flavus (Necrophloeophagus longicornis) (30-45 mm) Geophilidae Bright yellow blind centipede that forms burrows in the soil. Dark yellow head and 49-51 pairs of legs. Long antennae compared to other species of soil inhabiting centipedes. Found in most soils including gardens. Widespread and common. Image taken at Flint Castle, Flint, Denbighshire .

Tachypodoiulus niger (50 mm) White-legged snake millipede Julidae Possesses 41-56 cylindrical shiny black segments that can coil into a 'spring' when disturbed. The terminal segment is pointed and upturned slightly. Feeds on living and dead plant material such as mosses, algae and soft fruit e.g. raspberries. Found in leaf litter and under loose bark and stones in gardens, hedgerows, and woodland. Widespread and common. Image taken at Flint Castle, Flint, Denbighshire .

Elongated flattened arthropods with each body segment containing two pairs of legs. These are moved slightly out of synchrony with the ones in front giving a rippling effect. Generally slow-moving. Body segments are circular in cross-section. Feed on dead or living plant material. There are five types of millipedes - polyxenoid millipedes also known as bark dwellers or bristly millipedes, the only species in the UK is Polyxenus lagurus; glomeroid millipedes are 'rollers' that can roll up into a ball when disturbed e.g Glomeris spp; juloid millipedes are cylindrical and 'bulldoze' their way between soil particles e.g. Cylindroiulus spp; polydesmoid millipedes have flat-backs e.g. Polydesmus spp; platydesmoid millipedes are flat-bodied or borers e.g. Polyzonium germanicum. There are 61 UK species.

Millipede copulate by the male transferring a spermatophore onto the gonopods located on the side of one of the abdominal segments to the female gonopods. The sperm is stored until the eggs are laid up to months later. The males may be able to scoop the sperm of rivals out of the female.

Millipedes defend themselves by releasing noxious chemicals from special glands. These glands fall into three main types - (i) Type 1 glands (e.g. Glomeris spp) secrete a sticky secretion containing glomerin that is a sedative. This can 'knock out' attackers for up to 12h. (ii) Type 2 glands (e.g. Blaniulus guttulatus) are the commonest and are often brightly coloured. They secrete a range of foul-tasting chemicals such as benzoquinones. (iii) Type 3 glands (e.g. Polydesmus angustus) that secrete cyanide, if held an almond smell indicates production of this gas.

Glomeris marginata (~20 mm) Pill millipede Glomeridae Similar to the pill woodlouse (Armadillidium spp), but is generally dark slate grey with buff edges to each plate. Each segment has two pairs of legs. Unlike the pill woodlouse the final tailplate is unsegmented and broad. Rolls up readily if disturbed, not forming a perfect ball. Widespread and common. Feeds on fallen and dried leaves and other vegetation. Image taken at Martin Down, near Salisbury, Wiltshire .

Polydesmus angustus (~25 mm) Flat-backed millipede Polydesmidae Pale brown sculptured plates with wing-like extensions. Upto 37 pairs of legs. Feeds on decaying vegetation including plant roots. Found in leaf litter, soils, beneath logs and rocks and in compost heaps. Common and widespread. Image taken at Garston Wood RSPB reserve, Sixpenny Handley, Dorset .