Coleopterists have described about 350,000 variations on what we easily call a beetle. The bewildering variety of beetle body form is a testament to their unmitigated success on Earth and reveals strategies, wrought from millions of years of success and failure, of populations attempting to come to terms with ever-present biotic and abiotic environmental challenges, for beetles are evolving not in the world, but with it.

One of the smallest beetles in the world, Acrotrichia sp. from North America (actual size, right), is a diminutive 0.05 mm in length. The smallest known beetle in the world is Nanosella fungi, found in eastern United States, measuring in at a whopping 0.035 mm!

. (actual size, left)

Two of the world's largest beetles, Titanus giganteus and Callipogon armillatus, can each easily fill the palm of an adult human hand. Both specimens (left) were collected in French Guiana. Titanus giganteus measures from 12.0 - 20.0 cm in length. Less than 20 specimens were known in collections before 1957. Since then, hundreds of specimens have been collected in northern Brazil and French Guiana, yet still nothing is known of their biology.

The horned cetoniine scarab, Anisorrhina algoensis, on the flowers of Grewia sp., from southern Africa.

Many cetoniines aggregate when fermenting sap or fruit attracts them such as above from central Africa.