to use your example of a bumble bee... that is combo morph. A pastel x spider.

You cannot selectively breed to produce those. Pastel is one morph, and spider is another. Distinct genetics.

You can selectively breed pastels to get nicer pastels and you can selectively breed spiders to get nicer spiders. But you need a pastel and a spider to do this... and you can selectively breed the two together to get nicer bees.

Bruce