Dej

shield in which some see the image of a human face, or death's-head.

This genus contains twelve very similar but separate species, readily distinguished only by the structure of the genitalia (Roth 1969)- All normally inhabit caves, rock crevices, hollow trees, and cavities under loose tree bark. Blaberus parabolicus (tranga bakkas) lives under houses in Surinam and becomes a pest indoors when attracted to light at night (Bruijning 1959). Adults and the yellow-spotted, trilobitelike nymphs are often found together and exhibit subsocial behavior (Gautier 1978, Schal 1983). Males assume a dominant rank in dense groups, their status distinguishable by their erect posture and aggressiveness. An aggregation pheromone, containing undecane and tetradecane and other compounds of unknown function (Brossut et al. 1973), is secreted from mandibular glands in all stages and by both sexes. Females also produce a volatile sex pheromone that acts as a primary releaser of complex and lengthy male courtship activities. The repertoire includes intense in-termale fighting over calling females (Wen-delken 1977).

Nymphs are adept at burrowing in the soil or rotting wood to escape predation. Adults lead more exposed lives and are likelier to avoid harm by flying, releasing offensive odors, or kicking with their sharp-spined legs (Crawford and Cloudsley-Thompson 1971). They are often attracted to artificial light during their nocturnal wanderings.

The food of giant cockroaches consists of organic detritus that accumulates in their dank niches, including bat guano, rotting wood and fruits, seeds and other decomposing vegetation, and dead insects or animals at times.

The two common species, Blaberus craniifer and B. giganteus (fig. 5.10f) (Schal 1983), are easy to maintain in culture and are used in many laboratories for physio logical research (Lefeuvre 1960). Adults can live for as long as twenty months (Piquett and Fales 1953). Females internally incubate their oothecae; the latter contain about thirty to forty eggs.

Other very large Neotropical cockroaches are the four species of South American Megaloblatta (Blatellidae, Nycti-borinae). They often are over 8 centimeters in length. A Colombian specimen, whose overall length (head to wing tips) was measured at 10 centimeters (Gurney 1959), is the largest cockroach recorded.

References

Brossut, R., P. Dubois, and J. Rigaud. 1973. Le grégarisme chez Blaberus craniifer: Isolement et identification de la phéromone. J. Ins. Physiol. 20: 529-543. Bruijning, C. F. A. 1959. The Blattidae of Surinam. Stud. Fauna Suriname Guianas 2(4): 1-103. Crawford, C. S., and J. L. Cloudsley-Thompson. 1971. Concealment behavior of nymphs of Blaberus giganteus L. (Dictyoptera: Blattaria) in relation to their ecology. Rev. Biol. Trop. 18: 53-61. Gautier, J. Y. 1978. Le comportement social de Blaberus colosseus en milieu naturel; plasticité du système social. Ins. Soc. 25: 289-301. Gurney, A. B. 1959. The largest cockroach (Orthoptera, Blattoidea). Entomol. Soc. Wash. Proc. 61: 133-134. Lefeuvre, J. C. 1960. A propos de Blabera craniifer Burmeister 1838 (Insecte dictyop-tère). Soc. Seien. Bretagne Bull. 35: 145-161. Piquett, P. G., and J. H. Fales. 1953. Life history of Blaberus giganteus. J. Econ. Entomol. 46: 1089-1090. Roth, L. M. 1969. The male genitalia of Blattaria. I. Blaberus spp. (Blaberidae: Blaberi-nae). Psyche 76: 217-250. Schal, C. 1983. Blaberus giganteus (cucaracha, giant cockroach, giant drummer, cockroach of the Divine Face) and Xestoblatta hamata (cucaracha). In D. H. Janzen, ed., Costa Rican natural history. Univ. Chicago Press, Chicago. Pp. 693-696. Wendelken, P. W. 1977. The evolution of courtship phenomena in Blaberus and related genera with reference to sexual selection. Diss. Abstr. B37(8): 3816.

Green Cockroaches

Panchloridae, Panchlorini, Panchlora.

The best known of the forty or so species in this genus (Gurney and Roth 1972) are pale, translucent green, or some shade of gray or cream, the fore wings also with some dark mottling. They are medium-sized (BWL 25—30 mm) and elongate-ellipsoidal in outline shape. Both sexes have complete wings and a smooth, unmarked head shield. Occasional pink individuals turn up, the color an apparent symptom of viral infection (Roth and Willis 1960). Curiously, the virus, Serratia marces-cens, is also a human pathogen causing septicemia with a high mortality (Appel pers. comm.).

These conspicuous cockroaches are common throughout Latin America. Some species, such as Panchlora nivea (formerly cuben-sis) (fig. 5.10g), are transported widely by commerce, especially in shipments of tropical fruits. In nature, they live in the rotting trunks of palms where they feed on the decomposing brown fibers of the trunk, through which they make tunnels.

Females make a thin-walled, pale oo-theca that may be extruded during formation and then retracted into a broad sac where the eggs develop. When the embryos mature, the ootheca is reextruded. The nymphs free themselves from their developing membranes as the ootheca is forced out and drop to the substratum (Roth and Willis 1958).

References

Gurney, A. B., and L. M. Roth. 1972. A generic review of the cockroaches of the subfamily Panchlorinae (Dictyoptera, Blat-taria, Blaberidae). Entomol. Soc. Amer. Ann. 65: 521-532. Roth, L. M„ and E. R. Willis. 1958. The biology of Panchlora nivea, with observations on the eggs of other Blattaria. Amer. Entomol. Soc. Trans. 83: 195-208. Roth, L. M., and E. R. Willis. 1960. The biotic associations of cockroaches. Smithsonian Misc. Coll. 141: 1-470.

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