292 THE KNXOiAIOLUGISt's KECORD. 



/', aei/oii, I only took two of the thouscinds I saw. I captured some 

 coppers, males, on the hill slope between Findeln and Zermatt, and 

 supposed at the time that they were all one species, but on closer 

 inspection they proved to include some eight or nine ('hnjanphanu^ 

 virgatireae, and the remainder C. hippothoe var. euryhia, whilst among 

 them I had again taken an underside aberration, the spots on the 

 hindwings on one side only being elongated into narrow radial streaks. 

 Tn conclusion I may add that both Villars and Zermatt are not at all 

 bad places for the lepidopterist, and that my short experience of 

 Switzerland nuikes me long for another visit. 



Migration and Dispersal of Insects : Final Considerations. 



By J. W. TUTT, F.E.S. 



It would be well if future observers would discriminate, as far as 

 possible, between those movements which are made by insects from 

 one part of their ordinary breeding-grounds to another, and those 

 which make sudden and sweeping changes of location far outside the 

 limits of their breeding-grounds. We are quite conscious of the 

 difficulty of doing this, and see clearly that there is no very distinct line 

 of demarcation between them, because, whereas some great flights 

 covering hundreds or even thousands of miles would still keep 

 those species which have a very wide distribution within the limits of 

 their breeding-grounds, a movement of a few miles would take some local 

 species outside theirs. It Avoiild be irrational also to suppose that 

 any strict definition between local and migratory flights, based on the 

 above considerations, can exist, because what may be a so-called 

 migrating flight, if measured by distance, in one species, may become 

 a strictly local one if applied to another. Comparatively short local 

 flights in one species, then, may be just as truly migratory, and 

 undertaken for exactly the same benefit to the species, as are the 

 longer flights of other species. 



The evidence that we have collected shows very distinctly one fact, 

 ch., that, however irregular the direction of individual migrations or 

 dispersal movements may be, there is a tendency for them to assume a 

 general northward direction whenever they originate in the subtropical 

 regions north of the equator, and to assume a general southward direc- 

 tion when they originate south of the equator, that is, the tendency is 

 to spread from what may be considered more favourable to less favour- 

 able regions so far as the stress of climatic environment is concerned. 

 Scudder insists that some of the butterflies to which we have 

 referred — Amisia arrhippnx and Pi/raiiwis cardni — have return swarms 

 [I'.si/rhc, viii., p. 192, Ihitf.^. Xetv Eivjland, p. 1086), i.e., that 

 certain butterflies come north in spring, and that their progeny 

 return in autumn, and later Moffat {Hrport Ent. Sue. (hitaiia, 

 1900, pp. 44 et .s<v/.) has written supporting this view. Scudder 

 refers us {Ptiijclic, viii., p. 192) to his own and Kiley's evidence on this 

 point, but, as we had already reviewed this, our conclusions remain 

 unchanged. The assumption that the swarming of Anosia arcltippm in 

 autumn (which is evidently merely a roosting-habit of the species, the 

 insects selecting a favourable spot and coming up day after day from 

 all quarters to this place at the end of the afternoon, and dispersing 

 in the morning, bO long as the weather is favourable, as shown by 



