Thank you Joe for your question.

Flytraps actually get a good deal of their sustenance like other plants do, through the process of photosynthesis. During photosynthesis, plants use the energy of the sun to drive a reaction that converts carbon dioxide and water to sugar and oxygen.

However, in addition to synthesizing glucose, plants also need to make amino acids, vitamins and other cellular components to survive.

In the bogs favored by Venus Flytraps, the soil is acidic, and minerals and other nutrients are scarce. Most plants can't survive in this environment because they cannot make enough of the building blocks necessary for growth. The Venus Flytrap has evolved the ability to thrive in this unique ecological niche by finding an alternate means of getting key nutrients like nitrogen. Living creatures like insects provide a good source of the nutrients missing from the soil, and they also contain additional energy-laden carbohydrates.

Source: http://science.howstuffworks.com/life/botany/venus-flytrap2.htm