How long you steam one place will depend on the article you are steaming. The bed bugs will die with just a few seconds of steam hitting them. You must move the steam over the item slow enough to make sure the steam would reach the bug. For example, in a wood item, you can move along fairly quick through any cracks or gaps. If you are steaming an upholstered chair, you want to go over the fabric slowly, especially in any places the fabric gathers to ensure any hiding bugs or eggs will get hit by the steam for at least 3-5 seconds. Many times you will see them come out as you get closer to their hiding places. They will feel the heat coming and try to escape it.