How about actually treating them like respectable adults and using the honor system? If you start treating people like dogs, don't be surprised when they bite you. Woof.
Stop giving bullshit tests with bullshit restrictions, which is usually what drives people to cheat in the first place. Have you considered asking: what can I change so my students are able to successfully learn the material such that they won't feel compelled to cheat? Recognize that cheating students are a reflection of your apathetic educational strategy and ineffective testing model.
Here's an example of a bullshit test which exemplifies a few of the issues with apathetic educators: single-try tests. Students are only given a single attempt to demonstrate they've learned the material, with the result ultimately reflected in the final grade. The apathetic educator is unbothered by having failed to adequately prepare his students, despite his knowledge of their inability to accurately self-asses in an unknown topic. A caring educator would provide a way for students to diagnose and fix any gaps in their understanding in addition to as a path for them to raise their grade to an A if they demonstrate an understanding of all relevant course topics.