178 MIGRATIONS OF PAPILIONACEOUS INSECTS. 



dently been long excluded from the chrysalis, and 

 had perhaps travelled a considerable distance'. I 

 was unable to ascertain the direction from which 

 they came, neither could I discover the route! 

 which they pursued ; for a single day the species i 

 appeared every where in abundance, and the day j 

 after not one was any where to be seen. On thil 

 morning of the 10th, however, I observed a singMJ 

 one flying swiftly to the eastward ; and since thaf 

 time several others have been seen ; but, as thes^i 

 last were all perfect and uninjured insects, I dd 

 not consider that they formed part of the immense 

 flight which passed this place on the 8th. It willl 

 be remembered, also, that this same butterfly ift 

 the species which passed in such incalculable mull 

 titudes through Switzerland some years ago; ail* 

 occurrence, the description of which must be fami|| 

 liar to every student of entomology.* 



" Does not this ascertained fact, of insects thi 

 travelling in enormous flocks from one district 

 another, explain, in some measure, the sudc 

 appearance of a particular species in vast numbers; 

 in a neighbourhood where it is usually considered 1 * 

 rare ? It certainly does seem, in many instances, 

 to account for this phenomonon ; but still, it will ' 

 not equally apply in all. It would be wandering, 



* This circumstance is described at page 102, vol. i., and at 

 page 98 of the same volume in the first edition, 



