Epigeic spiders, their potential prey and competitors: Relationship between size and frequency.

In an analysis of 67 pitfall trap studies in different environments a positive correlation is found between the abundance of spiders and their potential prey, individual main prey groups and individual predator groups. The body-size of spiders and potential prey is significantly correlated both during the day in one locality and between five different localities. Spiders match the size spectrum of their potential prey by an almost equally broad spectrum, whilst the size spectrum of other predator groups is narrower. Therefore, in all size classes spiders exercise optimal predator pressure upon their potential prey. It is suggested that there may be a significant role for spiders as a multi-predator complex in reducing a multi-prey complex.