Here is a list of King snake Species and how to feed them.
Californian King Snake
Californian King Snakes eat a variety of food in the wild including lizards, snakes, rodents, frogs and birds. In captivity they will thrive on a diet of pre-killed mice. Hatchlings are not usually problem feeders and will eat a pinkie mouse three times a week if given the chance. Adults will eat two to three weaner mice or rat pups once a week. Californian King Snakes are aggressive feeders and soon learn that when the cage opens food comes in, so be careful when opening the cage to avoid being bitten. According to your pet Californian King Snake other snakes are food, so keep them separately.
Florida King Snake
Florida King Snakes are the biggest King Snake species and can easily reach 2m in length. These bulky snakes are powerful constrictors eat other snakes. A large Florida King Snake is able to kill and eat Rattlesnakes, Copperheads, Cottonmouths and any other venomous or non venomous snakes that share its habitat. In captivity Florida King Snakes will eat pre-killed rats and mice. Feed Hatchlings on pinkies once or twice a week. Feed adults several large mice once a week. Large adults can eat small rats.
Mexican Black King Snake
The Mexican Black King Snake is a smaller species reaching an average length of 1.2m. Feeding hatchlings is not usually a problem. Hatchlings need to be fed pinkies once or twice a week. Feed adults 2-3 weaner mice once a week. The Mexican Black King Snake eats snakes in the wild, so keep them separate from other snakes.
San Louis Pottosi King Snake
This is a small grey snake with red saddles from the desert regions of Mexico. This snakes diet consists of lizards in the wild and some hatchlings may refuse to eat pinkie mice. Rubbing the pinkie on a lizard will trick the snake into thinking it is eating its natural food. After a few scented meals the hatchling should start to eat unscented pinkies. To avoid this problem make sure the hatchling you want to buy is eating pinkies before you purchase it. Feed hatchlings once a week. Adults will eat several fuzzies or a weaner mice once a week. These snakes do eat other snakes in the wild so keeping them separately is advisable
Grey Banded King Snake
Feeding these attractive little snake can pose problems. Hatchlings often will not accept pinkies even lizard scented ones. These individuals may need to be fed on small geckos or skinks. My advice would be to purchase a Grey Banded King Snake that is around 6 months old. At this age it is almost certain that the snake is eating mice. Feed your adult snake several fuzzies or a small weaner mouse once a week. These snakes have cannibalistic tendencies and should be kept separately.
Tri – Coloured King Snakes
Tri-Coloured King Snake species include the Arizona Mountain King Snake and Californian Mountain King Snake. These snakes are small and eat lizards in the wild. Hatchlings will often refuse to eat pinkies even scented ones. Therefore it is best to purchase sub-adult specimens as they should be feeding on mice. Feed adults several fuzzies or a weaner mouse once a week. These snake come from cold areas and some individuals refuse to eat in winter because the instinct to hibernate kicks in. Feed snakes that do this twice a week in summer in order to avoid them losing weight in winter or reduce the cage temperatures in winter to allow them to hibernate. These snakes will eat smaller snakes and should be kept separately.