Abstract. The restricted animal communities of the high Arctic islands are due, in part, to extreme geographical isolation. Migration via wind currents is one mechanism by which invasion of new species may occur. Here, we describe immigration of the non‐resident migratory moth, Plutella xylostella, into Svalbard during 2000. This was associated with a warm south‐easterly air mass that crossed from W. Russia: moths appear to have covered the 800 km to Svalbard in under 48 h, flying at an altitude between 500 and 1500 m. These events thus provide a case study for wind‐dispersed movements of invertebrates to high Arctic regions. Climate change scenarios predict increased frequency of such air masses and also of the warm dry weather associated with increased aerial insect transport. The general factors determining successful colonization of the high Arctic by wind‐dispersed animals are discussed, using P. xylostella as a model species whose important life history and physiological attributes are well known.

The populations of the well-known forest pest, Dendrolimus sibiricus Chetverikov, 1908 stat.rev., were sampled in the European foothills of the Ural Mountains, Russia. D. sibiricus is a species distinct from the Japanese taxon D. superans (Butler, 1877). Another taxon from the Southern Urals, taxonomically close to D. pini (Linnaeus), is described here as D. kilmez sp.n. The synthetic female pheromones prepared for D. pini and D. sibiricus attracted equally well all three taxa present, and thus cannot be used to identify these species. The Ural populations of D. sibiricus show differences in external appearance, and as already in the 1840s Eversmann indicated that the species had caused local forest damage, D. sibiricus must be a long-established species in the Ural area. Thus, natural spreading westward of the pest is not to be expected. The five Dendrolimus species of the northern Palaearctic and the male genitalia are illustrated, and the distinguishing characters are listed. Two Matsumura lectotypes are designated.

Abstract. Fifty of the fifty‐six species of the genus Apamea known from North America and three Palaearctic species were analysed for lock‐and‐key characters in their internal genitalia, mainly in the male vesica and the female bursa copulatrix. There were an average of 4.5 such characters per species, structurally corresponding in the two sexes. Anatomically they form a postcopulatory but prezygotic isolation mechanism. In some closely related species, the internal genitalia are very similar, but these species have a precopulatory isolation mechanism in the presence or absence of male abdominal coremata. Closely related species did not have more lock‐and‐key characters than unrelated species, which is taken to indicate absence of character displacement. The anatomical distribution of the lock‐and‐key characters was examined and the organs of eight species are illustrated. The lock‐and‐key hypothesis has been abandoned by several earlier authors but mainly on consideration of external genitalia. In Apamea the invariable functional correspondence between sexes in the sperm transferring organs, and the overall species‐specifity of characters but non‐existence of interspecific differences under a precopulatory mechanism indicate that (a) lock‐and‐keys are functioning and (b) they act as isolation mechanisms. Alternative hypotheses of genitalic evolution are reviewed.

No abstract

In the autumn periods of 1994–2001, the migrations of the Red Admiral Vanessa atalanta (L.) were recorded from the Porkkala Bird Tower, 35 km SW of Helsinki, Finland. By far the best year was 1998, when 1240 migrant V. atalanta were counted. Generalized to a 100-km strip, this would mean a minimum of half a million butterflies. Radar observations indicated that a large proportion may have migrated above the visible range. The migrations took place on sunny days with cool northern winds (down to +10–13 °C). On warmer days with southern winds, V. atalanta individuals were stationary in the terrain. Other species observed to migrate south in the same way, but in much lower numbers, included Vanessa cardui (L.), Pieris brassicae (L.) and Autographa gamma (L.). These records help to resolve the “evolutionary puzzle” of why migrant butterflies and moths travel to northern latitudes when their offspring have such limited possibilities of returning to the south. Until now, the only butterfly for which high-elevation return migrations in northern winds have been known has been the American Monarch Danaus plexippus (L.). The mechanics of the flights, the migratory behaviour and their evolutionary significance are discussed in light of the literature.