Not all carnivorous plants eat the same kinds of insects. To know what carnivorous plants eat, learn to first identify them by their Latin botanical name, not their popular name. The botanical name has a genus and a species; the genus begins with a capital letter; the species starts with a small letter. The well-known Venus flytrap is Dionaea muscipula
Butterworts and Sundews
The butterworts, those belonging to the genus Pinguicula, and the sundews, those belonging to the genus Drosera, catch flying insects including flies, gnats and moths. These plants have sticky leaves that trap insects then close slowly around them.
Pitcher Plants and Monkey Cups
North American pitcher plants belonging to the genus Sarracenia, Asian pitcher plants, including the monkey cup, belonging to the genus Nepenthes and the Australian pitcher plant, the sole species in the genus Cephalotus capture ants, beetles, butterflies, flies, moths, wasps and other insects that forage. Pitcher plants lure their pray into a container filled with an aromatic, sticky poison.
The Venus flytrap, native to a limited area of North Carolina, is a popular carnivorous plant for gardens and terrariums because of its dramatic snapping action. Venus fly traps are better off if left alone to trap bugs, earwigs, flies,millipedes and spiders. There is no harm in placing a couple of these or other insects into a plant to watch the plant's trap snap shut.
Put a captured insect into a freezer to stun it, place it on the trap. When the trap is tapped with a toothpick or tweezers, it will start to close. When the insect begins to recover, it will move around; the trap will close completely and begin the process of digesting the bug.
Carnivorous plants in a garden filled with bugs can generally feed themselves. They will grow without being fed, only more slowly. Most carnivorous plants take a week to digest an insect. They go dormant in the winter when the insects are not active.
What to Feed
Some carnivorous produce their own enzymes to digest insects; others rely on bacteria. Do not feed hamburger or other meat to carnivorous plants. If they are fed, they should be fed those kinds of insects preferred by their genus and species. Wingless fruit flies are sold commercially as an all-purpose food.
Venus flytraps, sundews and most other carnivorous plants are not fertilized, but young pitcher plants in the genus Sarracenia will grow better if you fertilize them with a four-month slow release 19-6-12 fertilizer. Adult pitcher plants may lose their leaves or have less color if they are fertilized.