Coleoptera

Immature:

1. Head well-developed with ocelli and chewing mouthparts.
2. Three pairs of thoracic legs; no abdominal prolegs
3. Body form:
   • Campodeiform -- Slender, active crawlers
   • Scarabaeiform -- Grub-like, fleshy, c-shaped body
   • Elateriform -- Wireworms; elongate, cylindrical, with a hard exoskeleton and tiny legs

Adults:

1. Chewing mouthparts (sometimes located at the tip of a beak or snout)
2. Front wings (elytra) are hard and serve as covers for the hind wings; meet in a line down the middle of the back
3. Hind wings large, membranous, folded beneath the elytra
4. Tarsi 2- to 5-segmented 

 Ladybugs - Order: Coleoptera,
                     Family: Coccinellidae

Coleoptera (beetles and weevils) is the largest order in the class Insecta.   As adults, most beetles have a hard, dense exoskeleton that covers and protects most of their body surface.   The front wings, known as elytra, are just as hard as the rest of the exoskeleton.   They fold down over the abdomen and serve as protective covers for the large, membranous hind wings.   At rest, both elytra meet along the middle of the back, forming a straight line that is probably the most distinctive characteristics of the order.   During flight, the elytra are held out to the sides of the body where they provide a certain amount of aerodynamic stability.
Both larvae and adults have strong mandibulate mouthparts.   As a group, they feed on a wide variety of diets, inhabit all terrestrial and fresh-water environments, and exhibit a number of different life styles.   Many species are herbivores -- variously adapted to feed on the roots, stems, leaves, or reproductive structures of their host plants.   Some species live on fungi, others burrow into plant tissues, still others excavate tunnels in wood or under bark.   Many beetles are predators.   They live in the soil or on vegetation and attack a wide variety of invertebrate hosts.   Some beetles are scavengers, feeding primarily on carrion, fecal material, decaying wood, or other dead organic matter.   There are even a few parasitic beetles -- some are internal parasites of other insects, some invade the nests of ants or termites, and some are external parasites of mammals.

• Coleoptera is the largest order in the animal kingdom.   It includes 40% of all insects and nearly 30% of all animal species.
• The smallest beetle is the fringed ant beetle, Nanosella fungi (family Ptiliidae).   At 0.25 mm in length it is some 16 million times smaller in volume than the largest beetle, Goliathus giganteus (family Scarabaeidae), which may have a body length up to 10 cm.
• Two families of Coleoptera are bioluminescent (able to produce light).   Fireflies (family Lampyridae) and glowworms (family Phengodidae) have light-producing organs in the abdomen.   In some species, the females are wingless and larviform.
• Ancient Egyptians believed that a scarab beetle rolled the sun across the sky each day.   The scarab icon became associated with Ra, the sun god, and scarab beetles, Scarabaeus sacer, were worshiped as a symbol of immortality.
• Over 1000 beetle species are known to live as predators, parasites or commensals in the nests of ants.   They gain entrance to the nest by mimicking the odor and behavior of the ants.
• Bombardier beetles, Brachinus spp. (family Carabidae), have the ability to discharge a defensive spray of hot quinones.   Two chemical reactants are stored in adjacent compartments of an abdominal gland and combine explosively when the insect is disturbed.
• Males of many stag beetles (family Lucanidae) and scarab beetles (family Scarabaeidae) have enlarged mandibles or protruding horns which are used in courtship and in ritualized fights with other males.
• The Spanish fly, Lytta vesicatoria (family Meloidae), is the source of cantharadin.   This chemical, once thought to be an aphrodesiac, is now used as a mating stimulant when breeding cattle and in the treatment of certain urogenital diseases.