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This family was
treated by Roepke (1957) as the Squamuridae or as a subfamily, Squamurinae, of
the Cossidae. However, it is clear from Fletcher & Nye (1982) that the name
Metarbelidae of Strand has priority. Fletcher & Nye did not include
Squamuridae as a synonym but it must certainly be included as such.
The family is known
from the Oriental and Afrotropical Regions, being most diverse in the latter; a
few New World taxa are also attributed.
Adult
characteristics
Included
species are cossoid, lacking a frenulum and having venation as in Figs. 6, 7.
The forewings have a reticulate patterning on a pale ground as in many Cossidae.
The antennae are bipectinate in both sexes. The family resembles the Ratardidae
in having only one strong anal vein to the forewing.
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The male genitalia have a broad, flattened uncus and separate or fused
rather drumstick-like appendages from it, possibly gnathi. The valves are small,
rather rounded, with some modification to the sacculus.
The female genitalia are illustrated in Figs. 66, 90. They share with
the previous family, Ratardidae, several features that may indicate a close
relationship: deep, narrow ovipositor lobes that have dorsal rounded expansions;
a reduced ductus and corpus bursae; an expanded membrane between tergite 7 and
the genitalia. There is thus a case for uniting the two families, Ratardidae
having priority, but examination of the genitalia of male Ratardidae (at present
unknown) is needed to confirm this.
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Early stages and
biology
Gardner
(1945) distinguished larvae of Metarbelidae from those of Cossidae in terms of a
rugulose rather than smooth head which is not overlapped by the prothorax rather
than partly retracted. There is a wide gap between ocelli 2 and 3 whereas the
ocelli are arranged in a more or less even semicircle in Cossidae.
Gardner only examined one species, Indarbela quadrinotata Walker,
but the same characters are shown by Squamura disciplaga Swinhoe (D.J.
Carter, pers. comm.). They need confirmation from other genera such as
those of the more diverse African fauna before they can be applied with
confidence to distinguish the family.
The larvae are bark feeders, sheltering during the day in a short tunnel
in the stem of a healthy tree. They abrade the cambial zone in the bark
surrounding this tunnel at night, covering the zone of damage with a mass of
frass held together with silk (Roepke 1957).
Roepke recorded several tree species as damaged by Squamura maculata Heylaerts:
legumes such as Deguila and Albizia; fruit trees such as Theobroma
(Sterculiaceae), Citrus (Rutaceae), Mangifera (Anacardiaceae)
and Garcinia (Guttiferae). He recorded other species from Delonix (Leguminosae)
and Nephelium (Sapindaceae). Unpublished CIE records add Eugenia,
Psidium (Myrtaceae) and Ziziphus (Rhamnaceae) to the list.
Systematic
account
Only one genus is represented from Malaysia eastwards: Squamura Heylaerts.
The genus is not represented east of Sulawesi where a single endemic species, celebensis
Roepke, is found.
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