Description of the immature stages and adult genitalia of the banana scab moth, Nacoleia octasema (Pyralidae: Pyraustinae), from North Queensland.

The egg, larva, pupa and adult genitalia of Nacoleia octasema from North Queensland are described. The banana scab moth Nacoleia octasema (Meyr.) is an important pest of bananas in the island groups of the Southwest Pacific, the Malay Archipelago and tropical Queensland (Paine 1964). The need for an extensive taxonomic study of the species is apparent as, at present, geographically separated races with different food plants are considered to form a single species, and workers on the taxonomy of the Pyraustinae agree that N. octasema fits no existing genus (Paine 1964). Some characteristics of the egg, larva and pupa were described in general terms by Paine (1964). Although the adult has been described superficially (Meyrick 1886, Leefmans 1916, Paine 1964), no description or figures of the genitalia have yet been published. Descriptions ofthe external morphology ofthe egg, larva and pupa, and the genitalia of the adult are presented here. MATERIALS AND METHODS All specimens used in this study were collected from banana plants in North Queensland. Eggs were examined and measured using a stereomicroscope with an eyepiece micrometer. All larval instars were examined either as whole specimens in 80% alcohol or as slidemounted larval skins prepared according to Common (1965), the only modification being the use of acid fuschin stain instead of mercurochrome. Pupae were examined live or preserved in 80% alcohol. Illustrations of larvae and pupae were made using an eyepiece grid and squared paper. The nomenclature used for larval chaetotaxy is that of Hinton (1946) and pupal nomenclature is that of Mosher (1916). For genitalia studies, entire abdomens were fixed in 80% alcohol or dissected fresh. Before the genitalia were dissected, abdomens were treated with boiling 10% KOH for 10 min. Genitalia were stained in 5% mercurochrome for 2 min. for examination with a stereomicroscope or remained unstained for phase contrast microscopy. Illustrations of genitalia were made with the aid of a drawing tube; nomenclature used for genitalia is that of Klots (1956). 1. Depar tment of Primary Industries, P . O. Box 20, South Johnstone, 4859, Australia. Present address: P. O. Box 102, Toowoomba, 4350, Queensland, Australia. 2. Formerly of Department of Primary Industries, P. O. Box 20, South Johnstone, 4859, Australia. Present address: Commonwealth Department of Health, P. O. Box 123, Cairns, 4870, Queensland, Australia. 46 Pacific Insects Vol. 19, no. 1-2