It's not a pest so I thought it would be OK to post it here. This spider basically lives on Woodlouse (Roly-Poly or Pill Bug). Actually the common name gives it away, woodlouse spider, Dysdera crocata. This is my first sighting of one this year as I worked in the garden, yes I do bits in the garden.
As far as I'm concerned spiders are friends and are more than welcome in the garden. I could certainly do with a few of those Woodlouse spiders though. I wonder if they would eat millipedes as we seem to be inundated with them this year?