View Image Gallery of Family Bombycidae

This family is most diverse in the Oriental Region, but is recorded from all Old World zoogeographic regions. The New World Apatelodidae have in the past been regarded as Bombycidae but are now (Franclemont, 1973) considered distinct though allied to the Bombycidae, Eupterotidae and Anthelidae. Apatelodidae larvae tend to be hairy like those of the last two families, though one South American genus, Colla Walker, has larvae similar to those of Bombycidae. The relationships of the two families and their position within the Bombycoidea need further investigation.

Oriental Bombycidae fall into two lineages on characters of wing venation and male genitalia.

Figure 4. Venation in the two lineages of the Bombycidae: left, Mustilia dierli; right, Ocinara albiceps.

The first, with vein CuP present in both wings and often a vestige of the M stem present in the forewing cell, has all radial veins except R5 arising anteriorly from Rs (Fig. 4); the sclerites of segment 8 in the male genitalia are strongly modified. This group is typified by Bombyx Linnaeus, includes the Ocinara complex and Gunda Walker in the Sundanian fauna and the mainland Asian Rondotia Moore, and is also represented in Africa (the Ocinara group) and the Papuan Subregion (the divergent genus Elachyophtalma Felder (= Laganda Walker), diverse in New Guinea but also represented in the Moluccas and with one species in Sulawesi).

The second lineage has CuP absent and only four radial veins of which the posterior two arise posteriorly from Rs (Fig. 4); the M stem is not present in the forewing cell; the eighth sclerites of the male abdomen are only slightly modified. The lineage is typified by Mustilia Walker and includes Andraca Walker Prismosticta Butler, Oberthueria Staudinger and Pseudandraca Miyata. This group is the subfamily Oberthuerinae of Kuznezov & Stekolnikov (1985).

The Australian genus Panacela Walker has been included in the Bombycidae in the past but is now placed in a subfamily of the Eupterotidae (as discussed by Fletcher & Nye (1982)). The forewing venation has one radial vein absent as in Eupterotidae, and the configuration is generally concordant with that family, though M3 and CuA1 share a long common stalk. The frenulum is present. The larvae are densely hairy.

All Bombycidae have the dorsal zone of the hindwing pleated and often somewhat concave; this pleated zone is the most heavily patterned part of the wing. This feature is seen to some extent in Eupterotidae, especially Panacela. The frenulum is present but very short, rather stout. The male antennae are bipectinate throughout as are the somewhat shorter (relatively to wing length) ones of the females in the Bombyx lineage. In the Mustilia lineage the female antennae are much more weakly bipectiante (Prismosticta) or filiform (Mustilia, Andraca). The eyes in Prismosticta are hairy (Miyata, 1970).

Bell (MS) illustrated the resting posture of a Gunda species that may be characteristic for the Bombyx lineage. The wings are held out at right angles to the body (though the abdomen may be flexed to one side), with the dorsal pleats of the hindwing folded round onto the upper surface of the forewing.

In the male genitalia the uncus is usually bifid, though this state is secondarily lost in some Andraca species and genera of the Ocinara group such as Ocinara Walker itself and Trilocha Moore. The saccus is only strongly developed in the Bombyx lineage where it is variably associated or even fused with the bifid modification of the eighth sternite to form a joint structure reminiscent of the cubile of some Lasiocampidae. The gnathus is strong but often divided in members of the Mustilia lineage and strong in Bombyx, weak in Gunda, and lost in some members of the Ocinara group.

No features of the female genitalia are diagostic for the family but there are several of generic significance. Only Ocinara has a signum in the bursa in the Bombyx lineage, but one is seen in two genera of the Mustilia lineage; in the latter the ductus bursae exhibits a central spiral.

The eggs are variable in shape, usually rather flattened spheres, laid in clusters, lines or 'walls', sometimes covered with abdominal scales from the mother.

The most detailed illustrated account of larval morphology in bombycid genera in both lineages is by Miyata (1970), who also illustrated adult and pupal features. Other descriptions of larvae are by Sevastopulo in papers cited in the systematic account and by Bell (MS).

The larva appears smooth, but is usually densely invested with small secondary setae. All abdominal prolegs are present, with crochets in a homoideous biordinal mesoseries. The thorax is swollen in some genera, particularly those of the Bombyx lineage. There is usually a prominent horn in the centre of the eighth abdominal segment, a feature common to both lineages. Paired thoracic horns are not seen, but in Bombyx huttoni there are small paired horns on abdominal segments 1 to 7 (preserved material in BMNH). The caudal horn is strongest in members of the Mustilia group (Pseudandraca, Oberthueria) but reduced to a hump in Andraca, also a member of the group. This group appears to have a larval resting posture with anterior and posterior parts of the body adjacently erect away from the substrate, a disruptive cryptic posture seen also in some smooth, leaf-mimicking notodontid larvae.

Pupation is in a densely silken cocoon, the quality and fineness of which in Bombyx mori is the basis of the silk industry. The cremaster is rounded and finely setose in most genera but more rugose and spined in Prismosticta; Prismosticta also lacks sparse setae elsewhere on the pupa, present in other genera.

Host-plant relationships
There are numerous records of members of the Bombyx lineage from genera of the family Moraceae: Morus, Streblus, Ficus, Artocarpus. Miyata (1983) noted Bombyx mandarina as feeding on Malus (Rosaceae) and Diospyros (Ebenaceae) as well as Morus in Japan but all tropical records are from Moraceae. The Chinese Rondotia menciana Moore is also noted from Morus (Moore, 1885, Ann. Mag. Nat. Hist. (5), 15: 491).

Records for the Mustilia lineage are more diverse but there is predominance of records from the related families Symplocaceae and Theaceae:

Andraca albilunata:

Cudrania (Moraceae Sevastopulo (1940) as Cudranus)

Andraca apodecta Swinhoe:

Camellia (tea; Theaceae; Roepke, 1924)

Andraca bipunctata Walker:

Symplocos (Symplocaceae; Sevastopulo (1946)); Camellia (Roepke, 1924).

Mustilia falcipennis Walker:

Symplocos (Sevastopulo, 1946)

Mustilia phaeopera Hampson:

Camellia (Theaceae; Sevastopulo, 1940)

Oberthueria falcigera Butler:

Acer (Aceraceae; Miyata, 1983)

Prismosticta hyalinata Butler: 

Symplocos (Miyata, 1983)

Pseudandraca gracilis Butler:

Stewartia (Theaceae; Miyata, 1983)

Zoogeography and habitat preference
Only one of the Bornean species is endemic, namely Pencillifera purpurascens Holloway. The rest are represented on at least one other of the Sunda Shelf lands and five are also known from the Himalaya or range further.

Two of the more widespread species, Gunda javanica Moore and Ernolatia lida Moore, are shared with Sulawesi. That island shares an Ocinara with the Philippines and has single endemic species of Bombyx, Gunda, Ocinara and Trilocha. The fauna of Sulawesi is thus predominantly Oriental, only one species of the Papuan group, Elachyophtalma inturbida Walker, being represented there.

The majority of Bornean species are found in the lowlands, though Ernolatia moorei Hutton, Penicillifera purpurascens and Andraca apodecta Swinhoe are exclusively montane, the Penicillifera only known from tall montane forest that used to grow on the now ravaged Mesilau Plateau of G. Kinabalu. Two species, Penicillifera apicalis Walker and Mustilia dierli sp. n. range from the lowlands to the upper montane zone.

Bibliographic note
Dierl (1978, 1979) did not refer to the rather obscure publication by Lemee [ 1950] on the Lepidoptera of Vietnam. Three bombycid taxa were described from N. Vietnam, one a synonym of Gunda javanica as listed under that species. The other two were Bombyx lemeepauli, a good species in the Bombyx group (but probably not Bombyx) that has also been taken in N. Thailand, and Ocinara tamsi, possibly a synonym of one of the Trilocha or Ocinara species discussed by Dierl (1978).

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