Pyralid Moths

Pyralidae.

The remaining moths are all members of a large and economically important family. They are mostly small, but some are medium-sized with rather long labial palpi that project forward in front of the head. They have tympana, whose cavities open forward on the underside of the abdomen near the base. Many species fold their wing curiously, rolling them or otherwise doubling them to emulate sticks and other innocuous objects.

Sloth Moths

Pyralidae, Chrysauginae, Cryptoses choloepi.

Spanish: Polillas del perezozo.

Portuguese: Tragas da preguiga.

For a long time, an erroneous idea was perpetuated in the literature that the larvae of these moths as well as the adults lived amid the hair of sloths, feeding on algal masses that allegedly grew there. (Such masses do not exist, although a minute unicellular alga does develop in the fine hair straiae, imparting to the fibers a green color.) It has been discovered, however, that the caterpillars actually live in the dung of the sloth (Waage and Montgomery 1976). Adult female moths leave the host's fur to oviposit on the mammal's leavings when it descends once a week to the forest floor to defecate. The pupa are also found in the dung pile, and the newly emerged moths fly into the forest canopy to find a new host. Mating occurs on the body of the sloth (Greenfield 1981: 6).

Although they come to lights at night (Wolda 1985), these moths (fig. 10.12e) are normally seen only on the bodies of three-toed (Bradypus) and two-toed (Choloepus) sloths. More than one hundred individuals may be found on a single animal at a time. They are very active, slipping rapidly through the fur, aided by their small size (length when wings folded, about 12 mm), flattened body, and arrowhead shape. Their fore wings are dark brown, with three contrasting cream-colored longitudinal lines; the hind wings are dark gray-brown. The proboscis of the sloth moth is very short, but they readily drink in the laboratory; their liquid food in nature is unknown.

This species is common in Central America wherever its host occurs. There are four additional species of South American sloth moths whose relationships and biologies remain unstudied (Bradley 1982).

References

Bradley, L. D. 1982. Two new species of moths (Lepidoptera, Pyralidae, Chrysauginae) associated with the three-toed sloth (Bradypus spp.) 'n South America. Acta Amazónica 12: 649-656.

Greenfield, M. D. 1981. Moth sex phero-mones: An evolutionary perspective. Fla. Entomol. 64: 4-17. Waage, J. K., and G. G. Montgomery. 1976. Cryptoses choloepi: A coprophagous moth that lives on a sloth. Science 193: 157-158. Wolda, H. 1985. Seasonal distribution of sloth moths Crytoses choloepi Dyar (Pyralidae; Chrysauginae) in light traps in Panama. In G. G. Montgomery, ed., The evolution and ecology of armadillos, sloths, and vermilinguas. Smithsonian Inst. Press, Washington, D.C. Pp. 313-318.

Sugarcane Borer

Pyralidae, Crambinae, Diatraea saccharalis. Spanish: Barreno de la caña, barrenador de los tallos cañeros, taladrador de la caña de azúcar. Portuguese: Broca da cana.

This species has assumed major importance as a pest in Latin America because of the havoc it wreaks on sugarcane, one of the region's economically most important crops. The larvae (fig. 10.13b) bore into the internodes and often cause the death or significant decline of the whole plant. At harvest time, it is not uncommon to find that up to a third of the cane internodes contain larvae. They permit the entry of fungi and reduce the quantity and purity of the juice. In older canes, the tunneling of the borers causes the tops to die so that the stocks break off in strong winds. The larvae also attack rice and corn in a similar manner. The species is cosmotropical and is distributed widely through the West Indies, Central America, and South America to Buenos Aires Province.

The medium-sized (WS 18—29 mm) moth (fig. 10.13a) is pale straw colored, with black dots in a V-pattern on the also faintly black-streaked fore wings. Full-grown larvae are about 25 millimeters long and yellowish white with contrasting dark brown head and prothorax and spots at the base of the body hairs.

The females place their disk-shaped eggs on the leaves, overlapping them like roof tiles. The young larvae move into the apical funnel of leaves and feed first on the leaf surface, later moving into the stem. Prior to pupation, the mature larva makes a chamber, separated from the outside by a thin wall of plant tissue and lightly lined with silk. In this it pupates. To escape, the adult breaks through the thin wall.

The Amazon fly (Metagonistylum mi-

Flflure 10.13 PYRALID MOTHS (PYRALIDAE). (a) Sugarcane borer (Diatraea saccharalis). (b) Sugarcane borer, larva, (c) Giant pyralid (Myelobia smerintha). (d) Cactus moth (Cactoblastis cactorum).

nense), a tachinid fly parasite of the larvae, and the trichogramma wasp (Trichogramma minutum), which destroys its eggs, are released in cane fields to help in the borer's control. Other members of the same genus (Bleszynski 1969; Box 1931, 1956) also plague this crop in Mexico, Guyana, and Trinidad. These are D. considerata, D. magni-factella, D. grandiosella, and D. centrella.

The laboratory biology of the species is presented at length by Bergamin (1949: 6 If.).

References

Bergamin, J. 1949. Diatraea saccharalis. In A. Costa Lima, Insetos do Brasil. 6: 61-81. Escuela Nac. Agron, Rio de Janeiro. Bleszynski, S. 1969. The taxonomy of crambid moth borers of sugarcane. In J. R. Williams, J. R. Metcalf, R. W. Montgomery, and R. Mathes, eds., Pests of sugarcane. Elsevier, Amsterdam. Pp. 1—9. Box, H. E. 1931. The crambine genera Diatraea and Xanthopherne (Lep., Pyral.). Bull. Entomol. Res. 22: 1-50. Box, H. E. 1956. New species and records of Diatraea Guilding and Zeadiatraea Box from Mexico, Central and South America (Lepid., Pyral.). Bull. Entomol. Res. 47: 755-776.

Giant Pyralid

Pyralidae, Crambinae, Myelobia.

These pyralids are among the largest mi-crolepidoptera. Adults have wingspans of 10 to 12 centimeters (fig. 10.13c). They have long, pale brown, pointed wings and much resemble sphinx moths with which they are often confused. The larvae (bichos da taquara-quice) are borers in bamboo and taquaras (bamboolike grasses). Paraguayan Indians reportedly used the larvae pharma-ceutically. The head was believed to be deadly poisonous, while the intestinal tract contains substances that induce hallucinogenic trances (Schultes 1974). Adults congregate around lights in large numbers, even to plague proportions in Sao Paulo and Rio de Janeiro in recent history (Ihering 1917).

References

Ihering, R. 1917. Observares sobre a mariposa Myelobia smerintha Hübner em Sao Paulo. Physis 3: 60-68. Schultes, R. E. 1974. Alucinógenos tropicales americanos. Bol. Soc. Quim. Peru 40: 230~ 247.

Cactus Moth

Pyralidae, Phycitinae, Cactoblastis cactorum.

The cactus moth (fig. 10.13d) is a native of southeastern South America, where its normal hosts are prickly pear cacti (Opuntia). It was introduced from Argentina into Australia in 1914 and again in 1925, after the first trial failed, for the control of this plant that had become a weed, threatening to take over vast amounts of valuable agricultural and rangeland territory (Dodd 1940). Eggs are laid at the bases of spines, and the larvae tunnel into the pads, reducing them to a rotting mass. Others in the genus may be more effective control agents under some conditions and in other areas (McFadyen 1985).

References

Dodd, A. P. 1940. The biological campaign against prickly-pear. Commonwealth Prickly Pear Board, Brisbane. McFadyen, R. E. 1985. Larval characteristics of Cactoblastis spp. (Lepidoptera: Pyralidae) and the selection of species for biological control of prickly pears (Opuntia spp.). Bull. Entomol. Res. 75: 159-168.

Pantry and Granary Moths

Pyralidae, Phycitinae; Gelechiidae.

A number of small lepidopterans (Corbet and Tams 1943), commonly called meal moths, are pests of stored products, from warehouses to the home pantry. The most damaging of these in Latin America are the pyralid flour moths (Ephestia spp. and Anagasta kuehniella; fig. 10.14a) and the Indian meal moth (Plodia interpunctella; fig-10.14b). In the family Gelechiidae, there is also the Angoumois grain moth (Sitotroga cerealella).

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