My young pacman frog has been on a diet of night crawlers, small/medium crickets, and the occasional wax worm. Usually he adores the crickets, and will eat 5-8 at a time. (he eats every other day). For the past two weeks, he has refused crickets, and will only eat night crawlers. Is there a reason he has started to reject the crickets? Is it safe to let him only eat night crawlers?