Lithobius variegatus and L. forficatus occupy similar ecological niches and frequently occur together although there are differences in their distribution in the British Isles. An investigation of their food and reproductive cycles, being a preliminary step towards a further understanding of their ecological relationships, is described.

Lithobiomorph centipedes have hitherto been regarded as wholly carnivorous, but it is shown that these species feed on litter as well as small litter animals, the presence of litter in the guts of these species not being connected with the presence of animal remains. Whereas L. forficatus takes litter throughout the year, L. variegatus does so mainly in the winter.

Both species appear to lay eggs for a considerable part of the year, though there appears to be only a short period of sperm transfer in spring. It is suggested that the long oviposition period may prevent the loss of the entire brood in a dry summer. The succession of epimorph stadia in L. variegatus is described.

L. forficatus was more common than L. variegatus in the drior part of the woods studied.