One of the interesting things about futons is that the “mattress” typically has very little good harbourage for bed bugs. The sleeping surface is simply a large bag of stuffing with a zipper. The frame is often made of metal or varnished wood which the bed bugs would prefer to avoid. As such these futons are relatively easy to inspect for bed bugs. The bugs will be in the folds of the zipper or behind the buttons that hold the “mattress” together.
When inspecting these futons I have noted that the bed bugs tend to congregate at very end of the zipper where the zipper starts or ends. Pay particular attention to these areas. Also open the zipper and you will often find some bugs that made their way through the small hole by the end of the zipper into the bag itself. Some of the bugs, after finding their way inside the “mattress” will move a considerable distance into the bag.
I have noticed the same pattern with mattress encasements that are not sealed at the zippers. The bugs will make their way to the zipper, walk along the zipper to the ends, and climb inside the encasement. In one case I found bugs about two feet from the opening of the zipper on a mattress that had been encased preemptively. Folks who think they are helping matters with these improper encasements are sorely mistaken. The bugs just have an excellent place to hide protected from the exterminator’s treatments.
If you insist on using these encasements make sure they do not have holes. If the encasement has a zipper that can not be sealed make sure it is taped shut and inspected regularly to ensure it remains taped shut. Given the bugs can live 18 months or more you may find that you got rid of the bugs once and returned when the tape fell off.