Iguanas are classified as omnivores, so they will eat anything that they are given. That is especially true when you are talking about Iguanas in captivity, such as pet Iguanas. If you were to watch an Iguana in the wild, you would see that they eat mainly ripened fruit, grasses, and leafy greens. However, as we have said, they will eat anything that is given to them. Although the Iguana is a folivore, meaning that they prefer leaves, in the wild, they will feed on vines and the leaves of trees.
In the wild, you may well see some Iguanas eating insects. However, one thing to consider is that animal protein of any kind is bad for them. Furthermore, it can give them kidney issues if they have too much meat. Therefore, you should never feed them on any meat, whether that is live or dead insects, other pet food, or anything else that contains meat. An iguana who lives on meat is likely to develop very severe health problems, and may even die prematurely, with an increase in vet bills!