Bedbugs can sometimes hide in not only beds, cracks, along baseboards, under carpets and in crevices, but also on furniture. A couch is particularly difficult to treat because there are so many places for bedbugs to hide. Sometimes it’s better just to get a new sofa completely. Typically, these bugs want to be where people are sleeping at night because it’s easier to feed. So if someone is sleeping on your sofa, your floor or in a bed, they are susceptible to being bitten.
If you have an infestation bad enough that you need a new sofa, you have to be careful how you dispose of the old one. This is especially true if you live in a second floor apartment or higher. If you bang the sofa on the way down the stairs, the bugs could fall off and infest other floors. Wrapping it in plastic and duct tape will lessen the likelihood that they will spread.