no the flour goes across doorways or rooms - if the snake crawls thru it, ull know which way he went. u can try putting a mouse in a bag then ull hear the snake move into the bag. the trick with using plastic bags is sitting absolutly still in the dark so the snake will feel its safe to come out, another tip for using plastic bags is avoid air ducts, if the heat turns on the airflow will move the bag and ull think its ur snake.... how big is he ??