Thanks for th info.
No,unfortunately the house is not empty and it is difficult with the chemicals already.
I suggested treating the wood itself but the owner don't want it. Yes,the house is damp and they seem to be coming up by the edges and there are plenty more of them upstairs than downstairs. An other tricky bit, all floors are carpeted upstairs!!!
I was thinking of a special solution to wash down the wood, carpet etc with.
Is this an option?
I can't really get down to clean the carpet as the bugs are everywhere....