A STUDY OF DISPERSION AND MIGRATION OF LEPIDOPTERA BY LIGHT TRAP PAIRS

The dispersion of Lepidoptera and the behaviour of migratory species h as been studied on 24 nights with portable light traps placed on diffe rent hights of the surrounding terrain. It was observed that the upper traps had caught one and a half times more individuals than the lower ones. Differing results were got only on occasions when strong winds disturbed the flight. The number of migratory individuals caught in th e higher traps was about three times higher than the one in the lower traps. On adverse (cold) days the percentage of migratory individuals increases within the total catch, presumably because their inner heat regulation has adapted to low temperatures or they react to the unfavo urable environmental changes with increased activity (e.g. migratory f light). The higher activity is induced also by frontal changes that pr ecede measurable meteorological alterations. The activity of non-migra ting species depends to a much higher degree on weather changes, as sh own by the considerably greater fluctuations of their number in light trap catches. Finally, a ''subjective'' remark, as evident in Figs 1 a nd 2, the number of collected specimens was immensely (by orders of ma gnitude) higher in Asia compared to Europe, as a further indirect dist ressing proof of the impoverishment of our environment both from point of view of faunal abundance and diversity.