Drepaninae

The Drepaninae are characteristically the ‘hook-tips’, though many genera lack the strongly falcate forewings that this common name refers to. Others have the forewings bifalcate, with an angle centrally on the distal margin. The discal markings are often characteristically bipunctate.

The male genitalia exhibit a great diversity of structure, that extends often to modification of the eighth and sometimes seventh segments. The uncus is often deeply bifid, but its development is often rivalled or usurped by the socii that flank it. The valves can also be reduced. The ovipositor lobes of the female are frequently bilobed or more complexly divided, and the lamellae vaginales can also be of complex structure. The variety of genitalic structure can be appreciated from the figures presented here and also from the illustrations in the papers by Watson referred to later.

The larva has the anal prolegs vestigial, but the suranal plate is usually produced into a process or processes of variable length, giving the larva a tailed appearance. The crochets on the other prolegs are arranged in a mesoseries, together with a short lateroseries. A single verruca or pair of verrucae may occur dorsally on the thorax (Scoble, 1992).

Within the Drepaninae, authors (e.g. Watson, 1965_a_, 1967; Minet, 1985_;_ Scoble, 1992; Minet & Scoble, in press) recognise two subgroups, here placed at tribal level: the Oretini and Drepanini. Differences in development of larval secondary setae have already been mentioned. Drepanini larvae are distinguished by a supracoxal vesicle, possibly glandular, on each side of the prothorax (Minet, 1985). The adults of Oretini have the tongue reduced or absent, but it is better developed in Drepanini.

Whilst the Drepanini predominate in the Indo-Australian tropics and are the only group found in the Palaearctic, the Oretini are dominant in Africa (Watson, 1965_a_, 1967). The Drepanini larvae feed on a range of host-plant families whereas the Oretini show some preference for Rubiaceae. The genera Oreta Walker, Spectroreta Warren and Amphitorna Turner represent the Oretini in Borneo (See Oreta Walker et seq.).The sequence of genera from Euphalacra Warren to Drapetodes Guenée in the Drepanini shows a high degree of specialism for palm feeding but with Drapetodes on gingers (Zingiberaceae). They share a number of adult morphological features such as a tendency towards bifalcate forewings with strongly oblique, rather ‘ligneous’ fasciation, somewhat lamellate even when unipectinate male antennae, a bifid uncus that is not flanked by socii, single ovipositor lobes, the lamellae vaginales only weakly modified, and the ductus bursae long and slender. The larvae of many genera are characterised by spined scoli somewhat reminiscent of those of Limacodidae.

A further potential grouping of genera includes Macrocilix Butler, Hyalospectra Warren, Strepsigonia Warren, Canucha Walker, Leucoblepsis Warren and the new species tentatively associated with Ditrigona Moore (if not Ditrigona itself). Features common to these genera include: a tendency towards bifalcate forewings; occurrence of translucent patches in the postmedial area; a broad, shallow, four-lobed uncus structure; reduced, simple valves; a pronounced saccus. The three last features give the male genitalia a characteristic deep triangular appearance. The validity of this grouping requires further investigation.