The Birds and The Bees - Who's who and how did the phrase come about

This post is in line with our in-class discussion this morning about including gender and sexuality in the K-12 history curriculum and is part of the broader category of sex education.

I'm sure most of us are familiar with the phrase 'the Birds and the Bees talk' or something similar to that.

But what exactly do the Birds and the Bees refer to respectively? While I doubt there is a singular authoritative source or owner of the phrase, I looked up a variety of sources online and this is what I have gathered.

Essentially, the bees symbolize the ones doing the fertilizing, akin to bees doing pollination of flowers while the birds symbolize the ones doing the ovulation, akin to birds laying eggs.

Source: http://www.livescience.com/39316-birds-and-the-bees.html

And here is an LA Times article titled Birds Do It, Bees Do It,but Why We'd Say that? about the literary origins of the phrase:
http://articles.latimes.com/2000/sep/04/news/cl-15141