Buzz...

The Plover and the Clover can be told
apart with ease,
By paying close attention to the
habits of the Bees,
For ento-molo-gists aver, the Bee
can be in clover,
While ety-molo-gists concur, there
is no B in Plover.

-Robert Williams Wood - The Clover and the Plover


For the hardcore bug-lovers: I just heard about a new online Guide to the Identification of the U.S. and Canadian Bees in the Genus Perdita (East of the Mississippi River) by Rebekah Nelson and Sam Droege:

Perdita males

Perdita females

Their site also has a plethora of other online keys/guides well worth your browsing time. It's everything from fungi to bumblebees to dung beetles.