If he likes slugs, I would collect as many as you can for the winter. They are easy to keep, you can pm me if you like and I'll be happy to tell you how. They are also rich in calcium from what I read. Any kind of variation of food is good. That way when they refuse one, you can switch to another. And let me tell you, they will stick their snakey noses up at the very best of food when they feel like it! Spoiled snakes