1) The main distinguishing characteristic of the Coleoptera (sheath-winged) is thehardened forewings (elytra) six legs and antennae. In some cases the forewings are reduced ,
2) "Sheath" refers to the elytra which forms a protective covering over the membranous hindwings and the relatively soft dorsal abdominal wall.
3) All beetles have complete metamorphoses, i.e. egg-larva (several instars)-pupa- adult. It is that feature, complete metamorphosis, in combination with the elytra which characterizes insects of the order Coleoptera.
4) In addition to providing food for amphibians, reptiles, fishes, birds and mammals, a role which they share with most other insects, beetles play other important roles in the environment. Many, cantharids, scarabs, byturids, and others, are pollinators). Dung beetles (scarabs, geotrupids, and others) feed on and reproduce in the dung of herbivores, thereby removing millions of tons of dung that would accumulate and destroy valuable pastureland and natural areas. Burying beetles (silphids) inter animal carcasses which are then used as food by the adults and their growing offspring thereby ridding the landscape of carcasses that would otherwise contaminate and foul the environment. Various nest-dwellers (including histerids, trogids, staphylinids) and fur ectoparasites (such as leiodids, leptinines) rid their bird and mammal hosts of parasitic insects, such as fleas, bed bugs, and lice. Some beetles are effective as biocontrol agents which predate plant-feeding insects. Among these are ladybug beetles (coccinellids) which feed on aphids and scale insects. The Vedalia ladybug beetle in California reduced the scourge of the cottony cushion scale (Icerya purchasi). Carabid beetles, such asthe "caterpillar-hunters" (Calosoma, Carabus spp.) are often helpful in reducing populations of harmful caterpillars, such as gypsy moth and budworm caterpillars. Firefly larvae (glowworms) eat slugs and snails which damage such crops as tomatoes and lettuce.
These are just a few examples of the beneficial aspects of beetles, in addition to the delight one can find in their aesthetic beauty and remarkable diversity!
If you are interested in reading a good introduction to the beetles, beyond what can be found in the Peterson Field Guide to the Beetles by Richard White, or in an elementary textbook of entomology, look for a copy of the following book in a library, or on the used book market:
Branson, Wilfred S. (1963) - Beetles. Harcourt, Brace & World, Inc.,New York. 160 pages.
- contributed by Dr. Lawrence Kaplan
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Last modified on Tuesday, 12 November 2019