Do neither harm nor good but can be a sign the compost is on the dry side.

However the beggars can be a nuisance when one is turning the compost, its not a nice experience as they tend to run and inevitably one can get bitten, I learnt that the hard way, lol....

thanks for the reply's, I had heard about it being to dry, I don't know whether to put some ant powder on because they are just under the sheet, but I don't want to harm the worms as I have got plenty of them as well

Add water - if the heap is damp enough, the ants won't like it and will go away.

Thanks Bamboo, I am just in the process of building 2 new composters, as I have got to move the old ones to make way for a new chicken shed, so when I move the compost I might just keep adding a bit of water as I do so