This is pretty nifty; parasitic wasps can be taught to seek just about any scent, and they have a great sense of smell. This makes sense because these are tiny, stingless wasps, and they must find their prey, usually a caterpillar, a tiny island lut there in the sea of everything else. The female wasps lay their eggs in their prey and the larvae eat their host. Perhaps many of you have seen tomato hornworms, the caterpillar of an underwing moth, with a dozen or so white wasp pupae on its back (Go here for more info & image source). The damage having been done, the tomato hornworm is toast. Their sense of smell is so good a female wasp can detect if another wasp's larvae are already feeding within the host, and to avoid the competition, seek another host. Bed bugs are notoriously hard to detect and find, so these little wasps could be trained to seek bedbug pheromones. Then if you could get the wasps to reproduce on bedbugs you'd really have a great system. Maybe you can get these to go along with your TNT sensing plants! Can't wait until they come up with a kibble sensing cat. Oh, wait, already have those.