title: [Field study of the biology and ecology of Panaxia quadripunctaria (Lepidoptera, Arctiidae) on the Island of Rhodes].
abstract: 1. The paper covers a fifteen-month-study on the Island of Rhodes concerning the arctiid Panaxia quadripunctaria Poda, with particular reference to factors including the well-known mass meetings in the "Valley of Butterflies" of Petaloudes. 2. Outside Petaloudes, several habitats with less dense populations of Panaxia were found. 3. Extensive marking of butterflies proved that they emigrate from their primary habitats to Petaloudes in June and July each year. The extreme population density in Petaloudes results only from this immigration. In August, Panaxia is only found in Petaloudes, the other habitats no longer hold any population. In September, the remigration into the primary habitats was often noticed, but not vet confirmed by marked butterflies. 4. In September the butterflies copulate in the valley of Petaloudes, after which they return to their primary habitats where the females lay their eggs. 5. All butterflies participate in the migrations, but each one flies as a single individual; there is no group flight. The migrations take place at night only. Olfactory clues might work during the flight to Petaloudes. 6. Marked butterflies indicated that they may change their primary habitats before flyving to Petaloudes. 7. Each year, during the last days of June, all butterflies of the lower part of Petaloudes migrate towards the upper sections thus increasing the population already present there. The cause of this migration within the valley is unknown. 8. In the valley of Petaloudes the male butterflies favour resting-places near the ground, while the number of females increases with above the bottom of the valley. High up in the trees the females outnumber the males distinctly. 9. The habitats of Panaxia differ markedly from their surroundings by climate, light conditions and some other general factors. The striking difference between the surrounding climate and that of habitat during the day seems to function as an ecological barrier. Only at night, when the climatic differences decrease, the butterflies leave the habitats. 10. For the polyphageous caterpillars nutrition presents no problem because of the abundant flora in their habitats. Feeding butterflies were only rarely noticed. Judging from experiment with butterflies kept alive for abount 3 months without any food, Panaxia possibly needs no food during its adult stage. 11. There are several abiotic and biotic factors that influence the mortality (floods, enemies etc.), but their relative effects could not be ascertained. 12. In the primary habitats of Rhodes the hither to unknown ontogeny of Panaxia has been followed through one year: The development of eggs lasts from 8 to 15 days. The caterpillar-stage lasts 6 months. There are 5 moults. The following chrysalis stage lasts about 1 month. 13. The butterflies show differences in size, pattern and basic colour of the wings. Rather frequently the forewings of the same individual are differently coloured.
authors.affiliation: Abteilung Physiologie und Ökologie des Zoologischen Instituts der Universität Münster, Münster, Deutschland.|Hygiene-Institut für das Ruhrgebiet, 588, Lüdenscheid-Hellersen.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Elger