Why do they call it "the birds and the bees"?

Question:

Why do they call it "the birds and the bees"?

i'm referring to sex

Best Answer - Chosen by Asker: According to that story, a baby is created when a bee stings a bird. In some cases the choice of birds and bees may be because they provide a ready metaphor for insemination (pollination) and childbirth (hatching). However it may be called the "birds and the bees" in that it is simply the facts of nature; many creatures have sexual intercourse: birds, bees, humans, and a huge variety of others. - wikipedia

I asked this question a few weeks ago and someone gave me this wikipedia link. Kind of cleared it up, but still think it isn't the best metaphor I've heard.