Bagworm Moths

Psychidae. Spanish: Gusanos de cesto.

Portuguese: Bichos de cesto.

Bagworms are so named from the sac in which the larva and female moth spend their entire lives (fig. 10.12b). This is a tough case of silk into which are often incorporated bits of plant material, twigs, leaves, and so on, which camouflage it as well as give it physical strength. Only the head and thoracic legs project from the bag as the larva moves about while hanging from the undersides of its host parts. It is quick to withdraw if threatened. The bag is enlarged by the growing larva, protecting it from harm and serving as well for a cocoon for the pupa. Larval development, especially of the larger species, is prolonged and requires numerous supernumerary molts. Bag shape and arrangement

Figure 10.12 MOTHS, (a) Bagworm moth (Oiketicus kirbyi, Psychidae). (b) Bagworm, larva in bag. (c) Mexican jumping bean moth (Cydia deshaisiana, Tortricidae). (d) Mexican jumping bean moth, larva in seed, (e) Sloth moth (Cryptoses choloepi, Pyralidae).

of foreign objects are often diagnostic of species.

The adult male that escapes from the bag is fully winged and disperses in search of the flightless females that remain encapsulated. The appendages of the females of most species are vestigial, and the body is a largely amorphous membranous structure. The wing scales of the males of many are loosely attached and lost after emergence, leaving a portion of the wing membrane transparent. Mating takes place either inside or outside the bag. The former is possible because of the long telescoping abdomen of the male, which is inserted deeply inside the bag to come in contact with the female's genitalia. The eggs are normally deposited within the bag also.

There are approximately seventy Neotropical species of Psychidae (Davis 1964). The family is not well known, and new species are certain to appear as study continues. The largest genus is Oiketicus, with the widespread species O. kirbyi (fig. 10.12a) ranging throughout most of Central and South America and the West Indies. O. platensis is a pest of ornamentals in Argentina (de Briano et al. 1985).

Larvae are polyphagous, with wide host ranges, although they show a definite reluctance to change food abruptly during development. Some are injurious because of their attacks on ornamental plants.

In the past in Mexico, a sack containing the bag of a species of Oiketicus was hung on the front of a child's cotton garment for its magical effects. It was called quahqua-huini, or "woodsman worm," and was thought to ensure a good supply of firewood (Giordano and Beutelspacher 1989).

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