Beetles are the group of insects with the largest number of known species. They are classified in the order Coleoptera (from Greek κολεός, koleos, "sheath"; and πτερόν, pteron, "wing", thus "sheathed wing"), which contains more described species than in any other order in the animal kingdom.
Rita Skeeter
Rita Skeeter was an unregistered Animagus that turned into a beetle. Black beetle eyes are sold at the apothecary's in Diagon Alley. The rate was five Knuts a scoop the summer before Harry's first year at Hogwarts. Snape keeps a jar of these (dead ones) in his office.