Birds lay eggs and bees pollinate.

For the traditional story, birds are girls, bees are boys.

Hence the common UK slang of calling girls "birds" or in the US "chicks".

Ironic given that bee sexual reproduction is probably the least analogous to humans in the entire animal kingdom and the VAST majority of bees that you encounter outside the nest (and the only bees with stingers" are sterile female worker bees.