Life cycle of the earthworm predator Artioposthia triangulata (Dendy) in Northern Ireland

The terrestrial planarian Artioposthia triangulata was sampled weekly for 4 y using shelter traps. Numbers of trapped and individual planarian weights were recorded. On each sampling occasion, planarians were allocated to one of four size categories on the basis of their weight. These data are presented and the life cycle in Northern Ireland is deduced. Planarian growth occurs during the autumn-spring period and coincides with earthworm (prey) availability. Weight loss in the early summer is associated with egg capsule production. These capsules take over 2 months to hatch, so that recruitment into the population occurs in late summer.