Coleoptera is the formal name for the beetles. An order of the class Insecta. In the Coleoptera:
Coleoptera started to diverge about 265 million years ago, in the permian period. At the same time, cockroaches, dragonflies, sharks, and lizards started developing, but none of them worked as well as beetles. Currently, at least one fourth (300,000+) of all known animal species are of the order coleoptera, making them the most prolific animal order on earth. It is possible that there are over 12 million species of beetle.
Natural Acts by David Quammen (recomended for anywho interested in nature)
General Zoology by A. Franklin Shull (ed.)
Integrated Principles of Zoology by Cleveland Hickman, Sr.; C.H., Jr.; Frances Hickman.
http://phylogeny.arizona.edu/tree/eukaryotes/animals/arthropoda/hexapoda/coleoptera/coleoptera.html (Very Good site for all insect stuff).