Class Diplopoda (Millipedes)
Order Polydesmida (Flat-backed millipedes)
Genus Polydesmus Latreille 1802/1803
Length up to 25 mm.
One of the so-called ‘flat-backed millipedes’. The body colour varies from dull yellow to a dark brown, and they have around 20 body segments. The broad extensions to the body armour gives them a flattened appearance. The upper surface has characteristic pitted sculpturing. There are several similar species in the UK which require microscopic scrutiny of the male gonopods or female epigynal structures to accurately identify species.
Most species can produce toxic chemicals via glands in the body segments to deter predators. Seen throughout the year, they are herbivores which feed mainly on dead plant matter, but may also feed on seedlings or soft fruit which may become a pest in gardens or where crops are grown. Found in leaf litter, or beneath stones, logs and loose bark in woodland, grassland, farmland, parks and gardens. Fairly common and widespread.
Adults, juveniles and larvae found in local wood under loose bark, South Staffordshire. © Peter Hillman.