This and the next two genera contain moths that are very much smaller than
those of preceding genera. The forewings are narrow with an irregular,
centrally angled margin and a falcate tornus; the margin between the
central angle and the tornus is often dentate.
The tongue is short and weak in all three genera, with dorsal tubercles in
There is great variety amongst species of the three genera in the male
genitalia, the uncus varying from entire (C. decolor Walker) to widely
bifid (Smerinthulus quadripunctatus Huwe), and the aedeagus apex either
unadorned or with a laterally directed spur, C. decolor and S. terranea
having the latter state. Ornamentation of the valve offers no firm generic
characteristics, but C. decolor, the Himalayan C. pallens Jordan and the
Chinese C. uniformis Mell have very similar structure and evidently form a
natural group (see Jordan, 1931). C. ferruginea Walker from Sri Lanka
probably also belongs to this group.
There is thus a case for regarding the three genera as synonymous. All
species are Oriental, though C. decolor extends to New Guinea (D'Abrera,
The larva of C. pallens was described and illustrated by Bell & Scott
(1937). The head is strongly peaked. The thorax is pale green, the abdomen
darker. There is a broad dorsal stripe, dark green anteriorly, grading to
greenish brown. The oblique stripes are narrow, white or pale yellow,
edged reddish brown. The horn is green with brown tubercles.
The host-plant recorded was Betula (Betulaceae).
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