the size of prey does still apply to roaches, and all prey for that matter, but IMO with adults they can chew up prey better, therefore bigger roaches are not a big problem. the biggest i feed an adult bearded dragon is an adult DUBIA. i wont feed them like a full grown giant hisser which can get like 4-5 inches. some may not agree with that but i have not had any problems with feeding adults a bit larger prey. i feed my adult dragons rat pups or small hairless mice as well, they dont even pay attention to pinkies cause they are so small.
BUT when it comes to hatchlings, small dragons, and juvies, i stick to feeding prey only the size of the space between their eyes. nothing bigger.
the nice thing about roaches is most are soft bodied with very little "shell" compared to a cricket. theres a technical term for that but i cant remember it. anyways that being said, its easier for a dragon to digest a roach than it is a cricket. and more meat on roaches mean a fatter and healthier dragons.
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Beach Beardies
2.4. bearded dragons
1.0. Turquoise x Sunburst Veiled Chameleon
1.1. Sugar Gliders
0.2. Felines *queen athena and missy*