The only way a corn would eat an insect would be if it was forced down its throat or the insect was scented in some way. Corns are driven in large degree by their sense of smell, and that's why some lizard scents work to make pinkie eaters out of picky eaters. I have seen corns eat mice, lizards, chicks, and other small birds. However, the cheapest and most convenient prey item (to us) is the mouse. I wouldn't suggest you try anything else.