From my retired SerpenCo.com website.
Butter Corn Snake
Back in May of 1985, my wife and I were vacationing in southwest Florida and happened upon a pet shop in Cape Coral. They had an aquarium with about a dozen or so wild caught corn snakes in it and one in particular caught my eye. It was a female and the coloration was a rather unusual straw colored ground color with reddish-brown blotches. I just thought it might make a rather interesting looking amelanistic so I purchased it to take home.
The first season, I bred that female with a snow corn male and produced all normal babies, which was to be expected. I kept back several of them to raise up as future breeders. The following season, I mated her with a typical amelanistic male and again produced all normal babies. I also held back some of those.
When the first group grew up, I bred them together and got a handful of amelanistics but none of them looked especially interesing looking. As they grew up, they did appear to be a bit more yellow than a run-of-the-mill albino, but not exceptionally so. The same results were obtained when the second batch grew up and were bred. When all was said and done, I had retained 3 males and 5 females that were amelanistics, and I also kept one female from each of the two clutches from the original female.
In 1990 I moved to Florida and ALMOST sold all of those particular animals to a guy that expressed interest in them. But it was Winter time, and I figured I would go ahead and breed them together before getting rid of them. So in the Spring of 1991, I bred the 3 male amelanistics to their sibling sisters and also back to the two older females. When the eggs hatched, a couple of the snakes looked like snows, but not quite since they weren't as white as they should have been. Also got some things that looked like anerythristics, but they didn't look quite right either. I thought maybe I'd better hang onto those adults a little while longer until I saw what those babies were going to turn out to look like.
Well, those 'snows' got more and more yellow with every shed and those 'anerythristics' got more brown than black and even had some yellow coloration in the ground color. Subsequent breeding has determined that the 'odd anerythristc' is a unique gene that is not a form of type A nor type B anerythrism and is definitely a simple recessive gene. I therefore named this form the 'Caramel'. The Butter corn is, for the most part an amelanistic Caramel (or Snow Caramel, if you prefer). The reason I say 'most part' is because I believe there is still another influence in that blood line that appears to control the amount and/or intensity of the yellow coloration.
Basically the Butter Corn Snake is an all yellow corn snake. It still retains the typical corn snake pattern both dorsally and on the abdomen, but everything is in shades of yellows and white. In some individuals the yellow ground color can almost fuse with the blotch coloration giving you an almost uniformly yellow colored snake.
As in apparently most of the corn cultivars, the Caramel/Butters have their own brand of mystery attached to them. A while back I got the idea of trying to produce an all yellow corn snake with sharply contrasting black blotches. Now this certainly seemed like a feasible project, since there are plenty of 'A' anerythristics available that have a noticeable yellow wash all down the sides of the head, neck, and most of the body. So why not try to enhance this by mixing the obvious yellow influence in the Caramel/Butter line with 'A' anerythrism? I am sorry to say that this project was a nearly complete failure. After working with several generations from this project, I have NEVER produced what I was looking for. As a matter of fact, and the reason I say it was 'nearly' a complete failure is because I produced some truly outstanding 'A' anerythristics out of this project. The mind boggling result was that most of the 'A' anerythristics resulting from this project completely lack any trace of yellow on them. None. Nada. Zip. So how in the world did THIS happen? Is there an axanthic gene lurking in that mix? And if so, what affect is it having on a normally yellowish looking corn snake like the Caramels and the Butters? And to complicate this even further, most of the Snows and Ghosts produced from this project will often exhibit exceptional amount of yellow in them! It's like the yellow is lurking in those anerythristics, but it takes the addition of amelanism or hypomelanism to bring it forth.
Just another puzzle in the corn snake universe, I guess.