From my experience with my pacman frogs and the dubias, the reason they dont like them and spit them out at first is because the roaches PLAY DEAD. So...I started chopping their heads off which is gross, but it workd, they headless bodies roam around the tank till eaten, and when the frogs pick them up they are still moving and pulsating so the frogs continue to eat them. Now(months later) i dont have to chop them off at all and all my frogs love them and eat them veraciously. I do also feed them baby pinky rats and pinky mice depending on their size. The other great thing i feed them is horned worms OMG they love them soooo much.