. Economic entomology for the 164 AN ECONOMIC ENTOMOLOGY. CHAPTER VI. THE COLEOPTERA OR BEETLES. Fig. 126. The Coleoptera, '' horn-winged'' insects, or beetles, are dis- tinguished by the hard, horny, or tough, leathery texture of the fore-wings or elytra, which meet in a straight line down the middle of the back, and are not used in flight, serving as wing- covers only. They vary greatly, and are numerous in specimens and species, over twelve thousand kinds having been described from the United States and British America alone. They are as diverse in habit as in size and form, some
. Economic entomology for the 164 AN ECONOMIC ENTOMOLOGY. CHAPTER VI. THE COLEOPTERA OR BEETLES. Fig. 126. The Coleoptera, '' horn-winged'' insects, or beetles, are dis- tinguished by the hard, horny, or tough, leathery texture of the fore-wings or elytra, which meet in a straight line down the middle of the back, and are not used in flight, serving as wing- covers only. They vary greatly, and are numerous in specimens and species, over twelve thousand kinds having been described from the United States and British America alone. They are as diverse in habit as in size and form, some being among the most dangerous enemies of agriculture, while others are among the most useful. It seems at first sight as if the recognition of beneficial or in- jurious forms among so many would prove a hopeless task, and yet we find it in most cases possible to say at a glance whether a given specimen is herbivorous, , plant- feeding, or carnivorous, , flesh-feeding and predaceous. All beetles are mandibulate and chew their food ; but in one series the head is more or less prolonged into a snout or beak, at the end of which the much reduced mouth parts are situated. These are the Rhynchophora, or "snout-beetles," all of which are plant- feeders and injurious, or likely to prove so. The true Coleoptera, in which the head is not prolonged into a beak, we can separate by the structure of the tarsi or feet. Nor- mally there are five joints or segments to each pair of feet; but there are many de- partures from this rule, one large series having four apparent joints only, of which the third is lobed or deeply notched. The species in which this structure obtains are all plant-feeders ; either on leaves or in stems, trunks, branches, or roots ; often in dead, though more usually in living tissue. In no other case. Tarsi in Coleoptera.— c, normally five-jointed ; b, normally four-jointed ; c, four-jointed, with the third joint deeply lobed, from side and from above
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