Polyphaga

The Polyphaga is the largest and most diverse suborder of beetles. The name is got from two Greek words: poly-, meaning 'many', and phagein, meaning 'to eat', so the suborder is called the “eaters of many things”. Polyphaga has 144 families in 16 superfamilies, and shows an enormous variety of specialization and adaptation. It has over 315,000 described species, about 90% of all beetle species so far discovered.Grimaldi D. and Engel M.S. 2005. Evolution of the insects. Cambridge University Press, p371. Johnson, Norman F. & Triplehorn, Charles A. 2004. Borror and DeLong's introduction to the study of insects. 7th ed, Belmont:Brooks/Cole, 365–400, 428–429. 

 Classification 
There are 5 infraorders:

 Bostrichiformia — including furniture beetles and skin beetles.
 Cucujiformia — includes lady beetles, longhorn beetles, weevils, checkered beetles and leaf beetles.
 Elateriformia — includes click beetles and fireflies
 Scarabaeiformia — includes scarab beetles and stag beetles.
 Staphyliniformia — includes rove beetles and water scavenger beetles.

The infraorder Cucujiformia includes most phytophagous [plant-eating] beetles. Adoption of a plant-eating lifestyle promoted speciation and diversity in beetles, with Cucujiformia, especially weevils, forming a major radiation. Much of this adaptive radiation has taken place at the same time as the evolution of the flowering plants. "99% of phytophagous beetles feed on flowering plants".p399

 References