The familiar ladybug belongs to the animal kingdom's most successful order. Currently, more than 250,000 species have been discovered, but recent estimates suggest that there are some two million yet to be found. The order derives its name from the hard shell ('coleo-ptera' means, literally, 'sheath-wings'). In adult beetles, the forward pair of wings is hardened and large enough to cover the insect's back. This shell protects not only the beetle's body, but also its precious rear wings. Beetles are generally not strong fliers, as the forewings must be held wide open during flight, foiling the aerodynamics. They are, however, excellent runners, relying on their shells more than their flying wings to protect them from enemies. The Coleoptera account for almost half of all living animal species.