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The second method used for adult snakes is probing. This uses a dull thin metal probe that gets lubricated with water based lube and is placed underneath the cloacal scale towards the tail. Then gently as possible it is inserted into the openings. It will go only a few scales on a female and hit a firm muscular wall. If it is inserted into a male then it should go a few scale lengths deeper than a female and feel more bouncy and elasticity. If you want to be sure you can try probing both sides to see if you get the same result. .
Breeding.
Corn snakes are one of the most bred snakes and one of the simplest. There environment can be easily manipulated to create good breeding conditions. They are ready to breed by 18-24 months. Any morph of corn snake can breed together. In the wild, the males will fight to breed with the females but in captivity any snakes will breed. Just like in the wild they breed in the spring when things warm up. This can be done artificially by controlling the temperature of the enclosure. Before breeding, people like to prepare their female snakes by Brumation or simulating hibernation. They clear their digestive tracts and then cool them down, like the winter would in the wild. Then when you slowly warm them back up it will be like spring and simulate their natural breeding season. Then feed the corn snakes more than normal to prepare for breeding. Then put the male and female together in a container for breeding with a paper towel so no bedding will stick to the hemipenis and it makes it easier to see signs of mating. You will see yellowish liquid on the paper if they have breed successfully. You can leave them together for about a week or shorter. This will increase the number of matings and allow for more fertile eggs. This should only be done once a year for females since it is a taxing experience. It can be done twice a year but is not healthy. .
After 30-45 days you should move the mother into a box for egg laying.