Millipedes are important detritivors in most ecosystems as they promote the decomposition of dead plant material, thus stimulating microbial growth. Ingested leaf litter is particulated in the millipede gut, meaning that when egested as faeces more surface area is available for bacterial and fungal colonisation (Hopkin and Read, 1992 The Biology of Millipedes p. 4).
Two of the most common species of millipede found in Ireland are Tachypodoiulus niger and Polydesmus angustus. T. niger is commonly known for its tendency to curl up like a spring when disturbed. It is often found under tree barks (Chinery, 1987 Field Guide to the Wildlife of Britain and Europe p. 275). P. angustus has a flattened body (earning it the common name Flat-Backed Millipede) and resembles a centipede, but its two pairs of legs per segment identifies it as a millipede (Sterry, 2004 Collins Complete Guide to Irish Wildlife p. 172).
Both of these species are quite numerous, for example making up to 50% of the April diet of starlings (Lindsey, 1939 The Wilson Bulletin 51 pp. 176-182), but are often inconspicuous due in part to their presence in leaf litter but also because they tend to be nocturnal animals. Banerjee (1967, Oikos 18 pp. 141-144) observed that both species are most active during darkness from one hour after sunset till one hour before sunrise. Activity extends into the afternoon in the summer months.