How can you tell if bed bugs are in your wall?

You can tell if bed bug are in your wall or crawling on your wall if you see a flat round bug and see blood in it..strange ansewer..blood, they have been feeding..look around the out lets..i think that if you have an intense problem and you only noticed recently, then it could be traveling to you..remember, bed bugs can live for a year with out feeding..i also think that if they come back after an intensive treatment then,yes they are in your walls..bed bugs travel very easy from apt to apt..so do not let some one blame you unless they really can..people lie about infestation..they do and wait for it to travel..they can force it to travel by using chemicals..well thats what bed doctor does..one for the books..very hard to get ride of..must follow all instructions..rubbing alcohol works well with clothing..either treat night before or wash and let sit in machine,,add detergent because of the smell.but remember,, rubbing alchol, goes away quickly and so does the smell. spray a towel..come back in a hour.. no smell or stain.smell fresh..natures defense works well, but smells like cedar..read web site..use on everything, does not stain..the smell will go away in a week or mop with a floor cleaner..