Beetles make up the order Coleoptera (sheath-winged in Latin).  They are perhaps the most successful order on earth with the total number of known species exceeding 300,000.   In North America alone there are 111 families with roughly 27,000 species ³.   Due to their adaptability you can expect to find them almost anywhere on earth.  In fact, not only are they found in almost every habitat on earth but they also exist in the fossil record as far back as 245 million years ago.  They range in size from 0.25 mm up to 200mm.   In general, beetles can be distinguishing from other insects by the following anatomical characteristics: opaque armored forewings (elytra) which adjoin in a straight line down the center and cover the hind two thoracic segments and most of the abdomen, chewing mouth parts, two compound eyes and antennae that attach to the head between these eyes.

Beetle Anatomy

References

Beetle Metamorphosis