Thanks for the tips, I will try growing (or allow to survive) chickweed, I will also try derris. I have tried putting lime in the planting hole, but that was really for club root which I don't have fortunately. I was beginning to think the remedy would involve hairshirts and moonlight. I'll post the...

any ideas on controlling these perishers. I use the collars but it seems to be a waste of time. Although I still get a fairly good harvest of cabbages etc, root fly seem to be at plague proportions on the allotments. Does anyone use anything other than collars around the plants? Pooh