There’s been a recent flutter in wildlife circles in the Moorlands, as sightings are reported of a rare species that seems to be making a comeback. This is the woodlouse Oniscus elector-fluitans, a close relative of the Common Woodlouse (Oniscus asellus). The two look very similar but the former is easily distinguished by a green streak down its spine. Staffordshire Wildlife Trust has no records for its occurrence in the county but MCA have discovered a report

of early observations in the archives of Wolverhampton University* and there were records of sightings in Stoke-on-Trent some years ago. The first recorded observations in the Moorlands have been at Brough Park in Leek.

Generally, O. elector-fluitans has patterns of behaviour that are not dissimilar to other woodlouse species. The species feeds on leaf litter, etc, but notably appears to like old newsprint and printed fliers. Its main predators are fast-moving ground beetles, the most successful of which are Pterostichus dextrorsus and P. sinistrosus, which can be identified by the metallic blue sheen on the wing cases of the former and a red sheen on the latter. A less numerous long-standing predator, P. popularis, seems to be increasing in numbers at present but not at the same rate as the more recent arrival P. viridis.

The woodlouse’s habitat is mainly in shady areas in woodland and parks, under stones and in litter bins, although in very urban areas it favours hiding in the crevices of old red-brick walls. Like most other woodlice, it avoids light (has a negative phototaxis in the scientific jargon) but does have positive carbon- and hydro-taxes. The former may explain its preference for newsprint but some of its choices appear to be contradictory. For example, it feeds on paper from a full range of newspapers and unexpectedly likes the Sun, despite its usual preference for shade. Clearly more research is needed to explain this somewhat cryptic behaviour.

It usually has a limited range and narrow horizons, although at the height of its periodic population explosions, which occur on an approximate 4 year cycle, it can exhibit very erratic and unpredictable responses. Hence the nickname ‘gullibility streak’ that has been given to the green streak on its spine. It looks as though the species is currently moving towards the peak of one of these cycles, so now is an excellent time to go looking for it.

Do please get in touch with your observations if you’re successful.

*Images are reproduced here with the author’s permission.