The rule about food not being bigger than the "distance between the frog's eyes" applies mostly to insects due to their harder part bodies like the head being an impaction issue. When it comes to softer foods like earthworms, it depends more on the mouth/stomach size. For Pacman frogs, babies should get mouth sized pieces; juveniles 2-3 in. can handle body length pieces; and adults 3.5 to 4 in. and up can handle whole night crawlers with no issues. Good luck!