The
Coleoptera is the largest order of insects; it contains about forty percent
of all known species. It includes the beetles and weevils. Among
the more than 250,000 species are many of the largest and most beautiful
of all insects. Some have brilliant metallic colors, showy patterns
or striking forms. Beetles can usually be recognized by their two pairs of wings. The first pair is modified into horny covers (elytra) that hide the rear pair and most of the abdomen. they usually meet down the back in a straight line. Coleoptera occur in nearly all climates. They may be divided into four groups: the first three, the Archostemata, the Adephaga, and the Myxophaga, contain relatively few families; the majority of beetles are placed in the fourth group, the Polyphaga.
Information provided by: http://www.arthropod.net