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 
appeared every where in abundance, and the day 
after not one was any where to be seen. On the 
morning of the 10th, however, I observed a single 
one flying swiftly to the eastward; and since that 
time several others have been seen; but, as these 
last were all perfect and uninjured insects, I do 
not consider that they formed part of the immense 
flight which passed this place on the 8th. It will 
be remembered, also, that this same butterfly is 
the species which passed in such incalculable mul- 
titudes through Switzerland some years ago; an 
occurrence, the description of which must be fami- 
liar to every student of entomology.* 
“ Does not this ascertained fact, of insects thus 
travelling in enormous flocks from one district to 
another, explain, in some measure, the sudden 
appearance of a particular species in vast numbers, 
in a neighbourhood where it is usually considered 
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 yolume in the first edition, : 
