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Figure 9.8 SCARAB BEETLES (SCARABAEIDAE). (a) Caliper beetle (Golofa porteri), male, (b) Caliper beetle, female, (c) Ox beetle (Strategus aloeus), male, (d) Flower scarab (Gymnetis holo-cericea circumdata). (e) Green fruit beetle (Cotinus mutabilis).

without horn 2—8 cm), brown to black, horned scarabs. Dechambre (1979) recognizes twenty species, ranging throughout the moist, forested regions of the Neotrop-ics. Males of all species have a single, median, elongate prothoracic horn, which opposes an equally well-developed head horn. The former is very erect but down curved at the tip, which may be variously widened or spade shaped in the different species. The function of the prothoracic horn has not been seen but may act with the head horn as a clamp for transporting females.

The caliper beetle (G. porteri) is the best-known golofa. Large males (fig. 9.8a) have exceedingly long, slender horns and remarkably elongate forelegs with large tarsi sporting thick growths of golden hair on their undersurfaces. These elaborations (lacked by the female, fig. 9.8b) undoubtedly function as direct weapons in fights between males. Accompanied by stridula-tion and displays of the hairy areas, they may also be used to intimidate opponents (Eberhard 1977).

Adults of the torito de la cana (G. aegeon) feed on young sugarcane plants and at times are pests in Peru (Wille 1952). Larvae of G. eacus attack the roots of corn plants in the same country (Ochoa 1980).

In the Sierra Nevada de Santa Marta of Colombia, these beetles have been seen battling for possession of single shoots of bamboolike grasses (chusquea) on which they feed (Howden and Campbell 1974).

Battles have been described by Eberhard (1980):

When two males confront each other, each holds on to the support with its middle and hind legs, wraps its long front legs around the other male's body and then tilts its prothorax and lowers its head so that the head horn is inserted under the other male's body. To begin an attack one of the intertwined beetles rakes its front legs sharply across its opponent's middle and hind legs. This action apparently serves to tear the opponent's legs from the support, and an instant later the attacker jerks its head up to throw the opponent off the support.

Because of the scythelike, toothed prothoracic horns, G. porteri, like male Hercules beetles, is alleged to be a sawyer of tree limbs.

References

Dechambre, R.-P. 1979. Le genre Golofa (Col. Dynastidae). Soc. Sci. Nat. (France) Bull. 23: 1—11.

Eberhard, W. G. 1977. Fighting behavior of male Golofa porteri beetles (Scarabaeidae: Dynastinae). Psyche 84: 292-298. Eberhard, W. G. 1980. Horned beetles. Sci.

Amer. 242(3): 166-182. Howden, H. F., and J. M. Campbell. 1974. Observations on some Scarabaeoidea in the Colombian Sierra Nevada de Santa Marta. Coleop. Bull. 28: 109-114. Ochoa, O. 1980. Ciclo biológico de Golofa eacus Burmeister (Coleoptera: Scarabaeidae), nueva plaga del maíz. Rev. Peruana Entomol. 23: 141-142.

VoiRiN, K. 1979. Détermination des especès du genre Golofa Hope (Coleóptera Melolon-thidae Dynastinae). Soc. Sci. Nat. (France) Bull. 23: 6-8. Wille, J. E. 1952. Entomología agrícola del Perú. 2d ed. Min. Agrie., Lima.

Ox Beetles

Scarabaeidae, Dynastinae, Oryctini, Strategus.

Ox beetles are large (BL 20-80 mm), robust, highly polished, reddish-brown to black beetles. The males generally have two moderately long, forward-pointing prothoracic horns and an equally long or longer, erect head horn, much like Mega-soma males, but the head horn is not bifurcate at the tip and is much less developed. The size of these horns, however, is a variable characteristic of individuals in the genus, as with other scarabs. It is evident that the males defend small individual reproductive and feeding territories, for which they fight, attacking with their pronotal horns, continuously up to two or three hours before one or the other desists (Morón 1976). Females are similar to males, except the anterior projections are only slightly developed and differ from Megasoma females in the convex rather than concave prothorax.

The genus contains thirty-one species with distributions covering all of Latin America, including the West Indies (Rat-cliffe 1976). The most widespread species is S. aloeus (fig. 9.8c), adults of which commonly come to artificial light during their nocturnal flights.

The larvae apparently normally feed on the decaying wood or pith of Agave and various trees, including palms. Adults feed on the juices of the larval hosts, occasionally burrowing into tree or cane trunks at ground level. Several are of economic importance because of the attacks of their larvae on the roots of sugarcane, mangoes, date palms, wax palms, oil palms, cacao, and pineapple. The coconut rhinoceros beetle (S. oblongus = quadrifoveatus) is a major pest of coconut. The principal damage results from the adults feeding on the germinal tissues of young trees. The sugarcane rhinoceros beetle (5. talpa = barbigerus) once was considered to be a similar enemy of sugarcane in Puerto Rico, but larvae actually have been found to feed only on rotting wood.

The larvae of this genus are occasionally eaten by aboriginals in Guyana and elsewhere (Bodkin 1919).

References

Bodkin, G. E. 1919. Notes on the Coleopteraof British Guiana. Entomol. Mon. Mag. 55-210-219.

Morón, M. A. 1976. Notas sobre la conducta combativa de Strategusjulianus Burmeister (Coleóptera, Melolonthidae, Dynastinae). Inst. Biol., Univ. Nac. Autón. México, Ser. Zool., An. 47: 135-142. Ratcliffe, B. C. 1976. A revision of the genus Strategus (Coleóptera: Scarabaeidae). Univ. Nebr State Mus. Bull. 10: 93-204.

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