66 ECOLOGICAL FOUNDATIONS OF ZOOGEOGRAPHY 



ing at most two faunal provinces, is very large in the caddis flies, 

 (Trichoptera) , and this may safely be ascribed to their weak flight. 42 

 Flightless grasshoppers have smaller ranges than winged species. Thus 

 6 fully winged species of the genus Platycleis and 12 with vestigial 

 wings occur in Austria and Hungary. Of the 6 species with complete 

 wings, 2 range over all of Europe and 4 into the Mediterranean 

 province, while of the 12 flightless forms, 5 are restricted to Dalmatia, 

 and one to the Swiss Jura. 43 



Of 45 species of Orthoptera which are common to the desert and 

 steppe fauna of central Asia and South Africa, not one has both sexes 

 flightless, and only a few have weakly flying females. 44 The mantid 

 species ranging farthest to the east in the Polynesian Islands belong 

 to the relatively small group without notable wing reduction in the 

 females. 44 The great power of flight of the hawk moths (Sphingidae) 

 makes possible a wider distribution of their species than of other 

 Lepidoptera: Celerio cingulata has a vast distribution, and the 

 morning-glory sphinx ranges throughout the Old World. Many indi- 

 viduals make extended flights; the morning-glory sphinx, which is 

 unable to gain a permanent foothold in east Prussia, is constantly 

 maintained there by an influx from the south; the oleander sphinx, 

 whose pupa succumbs to the winter in central Europe, is caught from 

 time to time in north Germany and even in Russia, and such speci- 

 mens must have flown from points south of the Alps; the death's head 

 has flown to St. Helena. The large American noctuid, Erebus odora, 

 has been taken on Tristan d'Acunha, about halfway between Monte- 

 video and the Cape of Good Hope, and is occasionally seen on ships 

 not far from the European coast. 45 



Some species of butterflies have a well-developed flocking instinct, 

 and large flights of such forms have been observed. Among these are 

 the thistle butterfly (Pyrameis cardui) which is absent only in South 

 America, and the common monarch butterfly which has spread across 

 the Pacific via the South Sea islands to Australia in the past 40 years, 

 and is now the most abundant butterfly at Sydney. The latter species 

 has recently appeared at various places in India and Europe and on 

 the English and Spanish coasts. 46 A flight of more than 20 Papilio 

 hector came aboard the Novara 300 km. from Ceylon. 47 Dragonflies 

 also present powerful fliers. Pantula fiavescens sometimes appears in 

 numbers on the Keeling Islands, and dragonflies were observed daily 

 above the water on a journey made from Singapore to Sydney during 

 calm weather. 48 Great swarms appear frequently, and such swarms 

 have even been reported for the backswimmer {Notonecta glauca) . 

 Mountain tops, especially in the tropics, may swarm with flying 



