The enzymes can only start to break down prey after cracks appear in a creature's outer covering. Some enterprising spiders stop by to pull out prey that has fallen inside a pitcher plant. And this may actually help the plants, too. Tiny insects and spiders are easy to digest, but bigger prey may not break down properly. If undigested, the carcasses may putrefy and destroy the leaf.
Diving ants come to the rescue by seizing and removing overly large prey.
Just think of it as housekeeping service. Order plants from a catalog. Try a Venus' flytrap as a start. Plastic planter with a drainage hole at the bottom. A 4-inch pot will hold one Venus' flytrap.