Bombycidae

The family Bombycidae is most diverse in the Oriental Region but is represented throughout the Old World. The New World Apatelodidae were once included but are now considered a distinct, allied family. Oriental Bombycidae are generally separated into two main lineages, typified by the genera Bombyx and Mustilia, which differ in wing venation, genitalia, and other characteristics.

Adults

The two main lineages within the family can be distinguished by several features. The Bombyx lineage often has a vestige of the M stem in the forewing cell, while the Mustilia lineage does not. All Bombycidae have a pleated dorsal zone on the hindwing, which is often the most heavily patterned part of the wing. Male antennae are strongly bipectinate, while female antennae vary from bipectinate in the Bombyx lineage to filiform in some of the Mustilia lineage. A characteristic resting posture involves holding the wings at right angles to the body with the pleated hindwing folded over the forewing.

Eggs

The eggs are typically flattened spheres and are laid in various formations, including clusters, lines, or “walls”. They are sometimes covered with abdominal scales from the female moth.

Larvae

Bombycid larvae generally appear smooth but are covered in small secondary setae. A key unifying feature across both lineages is a prominent, single horn on the center of the eighth abdominal segment. The thorax can appear swollen, particularly in those of the Bombyx lineage. Larvae of the Mustilia group are noted for a disruptive cryptic resting posture where the front and rear of the body are held erect, away from the surface.

Pupae

Pupation occurs within a densely silken cocoon. The quality of the cocoon from the species Bombyx mori is famously the basis for the entire silk industry. The pupa typically has a rounded, finely setose cremaster at its tip.

Host-Plant Relationships

The two lineages show distinct host-plant preferences. The Bombyx lineage, including the genus Ocinara, primarily feeds on plants from the family Moraceae (mulberry family). The Mustilia lineage has a more diverse diet but shows a strong preference for the related families Symplocaceae and Theaceae (the tea family), with records on Camellia and Symplocos.

Zoogeography and habitat preference

Most Bornean Bombycidae species are found in the lowlands. However, a few species, such as Andraca apodecta, are exclusively montane. Some species are widespread across the Sunda Shelf and into the Himalayas, while only one Bornean species is currently recognized as endemic.