Touch Sensitive Plants Are So Interesting

The world of touch sensitive plants is so neat and interesting, especially the one called Venus Flytrap Plant. I wonder why some plants are like that, and how they developed to be that way? I also wonder about their environment, and what types of insects are most likely to fall for the trap. How did they develop to know exactly where the insect is, so they can close their mouths at exactly the right time? Who were the first scientists to discover these plants, and how did they find out they were sensitive to touch?