Beetles Order Coleoptera

Identification: FW {elytra) horny or leathery, nearly always meeting in a straight line down back and covering HW. HW (the ones used in flight) membranous, usually longer than FW, and folded beneath FW when not in use. FW occasionally short and not covering all of abdomen. 1 or both pairs of wings rarely reduced or absent. Antennae usually with 11 segments, rarely with more, often with 8-10, rarely with as few as 2; antennae variable in form. Mouth parts chewing. Tarsi usually 3- to 5-segmented. Abdomen commonly with 5 segments visible ventrally, sometimes with up to 8. Metamorphosis complete.

Similar orders: (1) Dermaptera (p. 98): abdomen with pincerlike appendages at tip. (2) Hemiptera (p. 112): mouth parts sucking; front wings rarely meeting in a straight line down the back, nearly always overlapping at tip; antennae with 4 or 5 segments. (3) Homoptera (p. 128): mouth parts sucking. (4) Orthoptera (p. 76): front wings with distinct veins (beetle FW lack veins); antennae usually long, threadlike, many-segmented.

Immature stages: Larvae quite variable in form, hardness of body, and development of appendages: campodeiform (like Camp odea; see illus., p. 63), grublike, or wormlike; some are wirewormlike, and a few are greatly flattened. Feed in the open or burrow into the food material. Occur in a great variety of habitats; many are aquatic.

Habits: This is the largest order of insects. Its members are almost everywhere and feed on all sorts of plant and animal materials. They are abundant on vegetation; they occur under bark, stones, and other objects; many are found on or in the ground, in fungi, rotting vegetation, dung, and carrion. Some are aquatic. A few are parasites of other animals.

Importance: Many plant-feeding beetles are serious pests, and different species attack nearly all parts of plants. Some beetles feed on various stored foods and other materials. Many beetles are of value because they prey upon and help to control injurious insects or act as scavengers.

Classification: Three suborders, Archostemata, Adephaga, and Polyphaga. Archostemata are a primitive group with only 2 rare families. Adephaga have the 1st abdominal sternum interrupted in the middle by the hind coxae. At least the hind part of this sternum extends completely across the abdomen in the Polyphaga. The superfamilies and families of beetles are usually separated by characters of the antennae, legs, head, pronotum, front wings (elytra), thoracic sclerites, and abdomen.

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