Imosca megastigmata Hampson

Borsippa megastigmata Hampson, 1894, Fauna Br.India, Moths, 2: 518.

Diagnosis

See the generic description.

Taxonomic notes

The male genitalia of megastigmata are almost identical to those of sugii illustrated in the original description. However, the material reared by Bell in S. India (see below) has the costal dark patch much narrower than in typical megastigmata, and the subtornal markings are absent; the posterior part of the postmedial pale line is less oblique.

Geographical range

Indian Subregion, Sumatra, Borneo, Peninsular Malaysia.

Habitat preference

Two specimens have been taken in the canopy of dipterocarp forest at 170m near the Danum Valley Field Centre, Sabah (S.J. Willott, unpublished data).

Biology

The larva was described by Bell (MS) and Gardner (1948a; only tentatively identified as megastigmata), is elongate, with constricted segments. The prolegs on A3 and A4 are reduced to small cylinders. The crochets are appendiculate. The head is relatively large, broader than high, granulate and shallowly bilobed, the setae arising from chalazae. The colour of the larva is a light translucent green, glaucous subcutaneously. On the body there is a darker, fluctuating dorsal band bordered on each side by finely wavy or broken white lines. There is a more distinct, broken, yellow dorsolateral line and an even more fragmentary spiracular one. The dorsolateral line can be tinged with pink in places. The head is also lined and more generally tinged and spotted with yellow. The larvae live on the undersides of youngish leaves, eating from the edges irregularly, and are active, restless, with a leech-like motion. They squirm and jump like fish when intensely alarmed. Pupation is in the soil in a strong, ovoid, silken cell. The host plants are as stated in the generic account.