Chilean Stag Beetle

Lucanidae, Chiasognathinae,

Chiasognathus granti. Spanish: Ciervo volante, cantabria, cacho de cabra (Chile). Mapuche: Llico-llico (Chile).

This beetle achieved notoriety as a result of its inclusion in Darwin's discussion of sexual selection in his The Descent of Man. He knew the species from his visit to southern Chile, the male of which he described as "bold and pugnacious," and "when threatened he faces round, opens his great jaws, and at the same time stridulates loudly. But the mandibles were not strong enough to pinch my finger so as to cause actual pain" (Darwin 1871). It has now been determined that the enormously long, toothed mandibles of the males (fig. 9.5h), with hooked tips and an angular bend downward at midlength, are used not for injuring enemies but as forceps for plucking rival males from their perches in trees and hurtling them to the ground below (Eber-hard 1980). The beetle's extra long forelegs assist in this process. According to Joseph (1928), some fights end in death by decapitation for the loser, his thorax and head being separated by the viselike jaws of the victor.

The male is otherwise a typical, medium-large beetle (BL 8 cm, excluding the mandibles, which are about as long as the body), with an olive prothorax and reddish-brown elytra, both regions being highly polished and with a pearly sheen. The females are smaller than the males and lack the enlarged mandibles (fig. 9.5g).

The species is fairly common in southern Chile and Argentina, appearing January to April. Most facts on its biology are recorded by Joseph (1928). Both sexes congregate around oozing wounds on the trunks of Nothofagus and Weinmannia trees, from which they feed. Very large numbers may appear in odd years. Males fly with facility at dusk and into the night.

Females deposit their eggs in the soil. The larvae (Cekalovic and Castro 1983) are subterranean and feed externally on the roots of shrubs and other plants. They form spacious cells for pupation, 30 centimeters or less below the soil surface.

References

Cekalovic, T., and M. Castro. 1983. Chiaso-gnathus granti Stephens, 1831 (Coleoptera Lucanidae), descripción de la larva y nuevas localidades para la especie. Soc. Biol. Concepción Bol. 54: 71-76.

Darwin, C. 1871. The descent of man, and selection in relation to sex. 2 vols. J. Murray, London.

Eberhard, W. G. 1980. Horned beetles. Sei

Amer. 242(3): 166-182. Joseph, C. 1928. El Chiasognathus grandtii Steph. Rev. Univ. (Univ. Católica Chile, Santiago) 13(5-6): 529-535.

scarabs

Scarabaeidae. Spanish: Escarabajos (General). Portuguese: Escaravelhos, cascudos (Brazil, adults). Paos de galinha, joaes torresmo, bichos bolas, bichos gordos (Brazil, larvae).

The most famous members of this large family (Moron 1984) are the sacred scarabs (,Scarabaeus and other genera) of ancient Egypt. The American tropics are rich in species, many of which are well known for their great size and curious habits. Most belong to five subfamilies: the dung scarabs (Scarabaeinae = Coprinae, 1,100 species); horned scarabs (Dynastinae, 620 species); June beetles or chafers (Melolonthinae, 1,500 species); flower scarabs (Cetoniinae, 200 species); and the shiny scarabs (Rute-linae, 1,200 species).

All scarabs are identifiable by the club of the straight antennae which is composed of three to nine flat plates that may be spread apart. Most are small to medium-sized beetles, but some are among the largest insects known.

Scarab larvae are all pale grubs ("white grubs") with a well-developed head, jaws, and thoracic legs and a C-shaped body. Most are plant feeders, usually on the roots, but others eat dung, rotting organic matter, carrion, fungi, and so on. Those larvae of large species that develop in rotting palm logs are avidly sought for food by natives of many areas; some (including the larvae of palm weevils) are even sold in the marketplace in Iquitos, Peru (papas). Adults generally are leaf, fruit, nectar, and flower eaters but also feed on decaying organic material (dung, carrion, etc.).

Reference

Morón, R. 1984. Escarabajos, 200 milliones de años de evolución. Insto. Ecol., Mus. Hist. Nat., México.

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