slugs can be caused by many things... My snakes this year were kept in a garage. the avg temp in the garage never dropped below 85 degrees for more than a day or 2. without the access to cooler temps, it's harder for them to develop eggs properly and the males sperm is often killed by hotter temps. that's why the mild winter affected me so much. now that a room mate moved out, they have been relocated into the house where i can control their temps better.