Many gardeners are under the impression that carnivorous plants need to eat insects for survival. In fact, they have to, but in a very restricted manner. In most cases, what plants to eat is not what insects eat. In most cases, the plants and flowers we see on our yards are there because someone decided that they would look good and that they would provide some benefit to the garden or landscape. They were not planted as a way to automatically feed off insects.
In many cases, the insects that an animal feeds on are attracted to the plants by their smell, taste or the vibrations that they produce. That is not the case with plants. Insects do not care about the color or the taste or the aroma of a plant.
Weeds are a perfect example of what I mean. Look at the beds of weeds right outside your house. Most of these plants are there because someone decided that they would look pretty and that they would provide some benefit to the landscape or garden. There is absolutely no correlation between the type or amount of insects that an organism consumes and the plants or flowers that it consumes. What plants need to eat is not insects.
What animals eat is what plants to eat. The plants that humans eat are plant matter. Animals eat other animals. Insects eat insect matter. This is true whether you eat meat, poultry, fish or eggs. Plants and animals are one in the same and they do not need each other for sustenance.
As far as eating goes, carnivorous plants do not have an issue with eating other plants. Their metabolism is designed to deal with that. The reason that plants do not have an issue with this is because they do not have anything else to base their digestion on but bacteria and starches. Other plant matter will break down at a much faster rate than bacteria and starches. In fact, these foods will simply rot and die before too long.
So, if carnivorous plants do not need to eat insects to survive, then how come people put them in their gardens? Well, this is a twofold question. The fact is that insects do provide food for some plants. They also provide some of the building materials that the other plants need to grow.
The other part of the equation is this. If you do not need to eat to survive, then you do not have to grow any plants to feed them. And, there are other benefits that come from growing plants that do not need to eat. These other plants can help to purify the air around your home. They can help to filter the water running through your pipes.
What people need to understand is that just because a plant does not eat, does not mean that it is useless. The fact is that some plants actually benefit from not eating. It is simply that they do not need to eat. In most cases, if you are trying to grow a vegetable garden, it will benefit to you to grow vegetables that need to eat.