What Bug Is That? The guide to Australian insect families.

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Castniidae

Overview

Because of their clubbed antennae and day-flying habit, earlier authors often thought the castniids closely related to the butterflies, a view that can no longer be upheld. All the Australian species belong to endemic genus, Synemon , which has been placed in its own subfamily by early workers; this needs reassessment.

Description

Medium-sized; head smooth-scaled, vertex with lamellar scales directed forewards, frons with piliform scales; ocelli present, large; chaetosemata absent; antennae with smooth-scaled flagellum, broadly clubbed apically; proboscis present or reduced, naked; maxillary palps small, 2-4-segmented; labial palps short, ascending; epiphysis slender, spine-like; spurs 0-2-4; legs smooth-scaled; fore wing broad, M present in cell, chorda present or absent, M 1 -M 2 cross-vein weak, CuP present or absent, 1A + 2A with long fork; hind wing with frenulum of 3 fine bristles in female, M present in cell, Sc + R 1 separate from or shortly fused with Rs near base, M 1 -M 2 cross-vein absent (cell 'open'), CuP present or absent; ovipositor long and telescopic. Eggs flat, fusiform, with prominent ridges. Early-instar larva with well sclerotised prothoracic shield, L1 and L2 approximate on one pinaculum on abdominal segments 1-8; ventral prolegs with 2 transverse rows of uniordinal crochets; mature larva of Synemon cossid-like, without prolegs and crochets and with a few secondary setae; tunnelling in monocotyledons or in silk-lined, adjacent tunnels in soil. Pupa with antennae swollen at apex, abdominal terga with 2 transverse rows of spines on T2-7 in males and T2-6 in females, and 1 row on T7 in females and T8 and 9 in both sexes. Spiracles large; cremaster absent; pupa in silk-lined tunnel or cocoon in larval gallery, protruded at ecdysis.

Distribution

Synemon (34 spp.) occurs widely in mainland Australia and reaches maximum diversity in southern W.A. The adults fly rapidly, close to the ground on sunny days. The hind wings of most species are brightly coloured while the fore wings are cryptically patterned. The larvae of S . magnifica feed on Lepidosperma viscidum ; they first tunnel in the butt of the host below ground level and later construct a vertical tunnel, projecting above the soil at the base of the host plant, in which pupation takes place (Common and Edwards 1981). Other species are known to feed on Danthonia laevis and Lepidosperma carphoides . The life cycle takes 2 to 3 years.

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