Crickets are essentially omnivorous opportunity feeders, which is one of the reason they do so well and can be such household pests. I'm sure they have "preferred" foods, but they'll eat almost anything, including things that aren't good for them such as carpet fibers, etc.

Since my son's cat decided to try and help himself to some crickets, and thereby released a whole bunch into the house, I think we're going to find them all over the place for at least a while.