MIGRATING MOTHS COLLECTED IN TOWER-MOUNTED LIGHT TRAPS IN NORTHERN NEW-SOUTH-WALES, AUSTRALIA - INFLUENCE OF LOCAL AND SYNOPTIC WEATHER

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