This paper reports olfactometer studies to determine the attractiveness of synthetic equivalents of plant volatiles to Helicoverpa armigera (Hübner) moths. Synthetic volatiles identified from host plants and other volatiles reported in literature as attractants to various noctuid species were tested in a two-choice olfactometer. Of 34 single chemicals tested, only seven were significantly attractive, and six were significantly repellent. However, when presented as blends of two or more volatiles, 21 of 31 blends tested were significantly attractive, and only one was significantly repellent. The most attractive blends were those containing four to six components, including aromatic volatiles primarily found in flowers, especially 2-phenylethanol and phenylacetaldehyde and volatiles found primarily in leaves, including green leaf volatiles and terpenoids. Some general principles in blending volatiles for developing attracticides for H. armigera are presented, including the need for blend complexity, the combination of volatiles from leaves and flowers, and early consideration of pragmatic factors such as price and toxicological profile.

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Catches of moths in tower-mounted light traps in northern New South Wales were analysed in relation to local and synoptic weather. Catches were correlated with windspeed, relative humidity and possibly rainfall. No correlations were obtained with temperature or moon phase. Catches were more likely to occur when winds were from the east, and were associated with wind shifts. There was a significant association with the passage of depressions or troughs, but not cold fronts. The traps were considered to be poor indicators of migration associated with fronts, because these were accompanied by high winds in which trap efficiency was reduced. Stepwise multiple regressions using temperature, relative humidity, rainfall and windspeed accounted for only about 25% of the variance, much lower than in comparable studies with ground level light traps. These results are thought to indicate that the trap catches were reflecting long-distance migration, which was usually associated with disturbed weather. Back tracking with upper wind data was used to define probable sources of moths. In the spring and early summer, these sources were predominantly to the north and west of the traps, in semi-arid pastoral and subhumid cropping zones. In the late summer and autumn they were predominantly to the south and east, in the humid pastoral and forest zone. These results are discussed in relation to the migratory strategies of several important agricultural pest species.

Light traps were operated between September and April for five years on towers on mountain tops at two locations in northern New South Wales, Australia. The traps were designed so that their lights could only be seen from above, and therefore only insects engaged in high altitude flight, presumed to be migrants, were captured. The catch consisted mostly of Noctuidae and Sphingidae. Sweep netting failed to reveal local breeding, and for many species there were few host plants close to the traps. A total of 51,580 moths were trapped at Point Lookout and 10,223 at Mt Dowe. Sphingids, mostly Hippotion scrofa (Boisduval), comprised 26.9% of the catch at Point Lookout, but only 2.6% at Mt Dowe, and there were more species of noctuids at Point Lookout (44) than at Mt Dowe (15). The most common noctuid species were Agrotis infiisa (Boisduval), Mythimna convecta (Walker), Helicoverpa punctigera (Wallengren), H. armigera (Hiibner), Dasygaster nephelistis Hampson and A. munda Walker.Known or suspected migrants comprised 94.6% of the catch at Point Lookout and 99.9% at Mt Dowe. However, there were at least 24 species not previously suspected as migrants. The seasonal distribution of catches varied between sites and years. Some species showed peaks in both spring and autumn in some years, but only in spring in other years. Many of the less common species were caught only in summer and autumn. Large catches were usually obtained overs short periods (1-2 nights), separated by long periods when catches were very low. These large catches, which were thought to represent major migrations, accounted for 76% of the catch in 3% of the trapping period at Point Lookout, and 87% of the catch in 2% of the trapping period at Mt Dowe.