CONTKIKT-TIOX TO THK T.TFK-HISTdRY (»K PSYfHK ZERMATTENSTS. 2Hi] 



to the subject. The more " hiil)ituiil " migrants, if, indeed, the term 

 liabitiiiil I'eally applies to their case, are by no means tlie most ]io-\vGrful 

 insects, nor are they apparently provided with any special development 

 which might furnish a clue to the explanation of their wanderin;;(s. It 

 is, therefore, difficult to connect the wide distribution of many species 

 with specially great physical strength and the large development of the 

 wing-muscles and wing-nervui-es, for many of the most powerful, 

 physically, of the dragonflies are exceedingly local, and there can be 

 little doubt that this distribution is due rather to a powerful inherent 

 migratory instinct than to mere power of wing. We have already 

 noted that I'fDitala flart'srrns, Fab., one of the most widely distributed 

 species, and a notorious wanderer, is not at all, in spite of its large 

 size, a conspicuously strongly-built species. 



The records of tliese migrating swarms are generally so vague and 

 uncertain that the data are altogether insufficient to make any useful 

 generalisations, although here and there the swarms are noted as pre- 

 ceding or coincident with hot and dry weather Avhen one might suppose 

 many of the pools in which their eggs should be laid are dried up, 

 and where the immediate necessity of finding a suitable place for ovi- 

 position might be considered a sufficient incentive to put in motion 

 the migratory tendency. There can be no doubt, however, that some 

 dominating influence impels these more abundant species (in certain 

 districts), which have proved their fitness for existence by spreading 

 over a vast area, to travel as far as possible, and such species by their 

 adaptation to various conditions of temperature and climate iire more 

 certain to survive in the struggle for existence going on around them. 



The dragonflies are more nearly allied to the Orthoptera (locusts, 

 grasshoppers, &c.) than are butterflies and moths, and, therefore, what 

 has been said concerning the probable origin of the migrating instinct 

 in that order {riili' preceding chapter) applies very strongly to the 

 order we are now considering. It must not be forgotten, also, that it 

 is necessary for many species of dragonflies to seek keenly for food, 

 and that the voracity of the species belonging to certain genera — 

 .T^'sc/nia, &c. — is appalling. It is not surprising, therefore, to find that 

 migrating swarms of butterflies are frecjuently noticed as being accom- 

 panied by one or other of the species of dragonflies that prey upon 

 them. In common with that of the Orthoptera, the instinct of migra- 

 tion probably arose in direct connection with want of food, and the 

 present conditions of life in many species necessitates its development 

 to a high degree of perfection. 



Contribution to the life=history of Psyche zerinattensis. 



Jiy T. A. CHAl'MAX, M.D., F.Z.S.. F.K.S. 

 A Psychid case, occurring freely in the neighboui-hood of Locarno 

 in the first and second weeks of April, 1S99, was obtained almost every- 

 where below 1,000ft. above lake level, and especially freely on the 

 rocks and walls near the lake between I'rissago and Ascona. Some of 

 these cases were already empty, some, at least, of these belonging to 

 the previous year, but certainly not all. Others still contained active 

 larvas a few of these, perhaps, wandering in search of food, others in 

 search of a place suital)le for pupation, but most of them larva-, simply 

 because very recently hung up for pupation. It was the case with this 



