THE ENTOMOLOGIST. 161 



observed. Yet I believe there is a regular migration of at 

 least one species (P. Hector) from India to the north-west of 

 Ceylon, whence it must find its way to other parts of the low 

 country. From the middle of February to the middle of 

 April 1 was usually at sea, cruising somewhere in the neigh- 

 bourhood of the Pearl Banks; and during certainly three 

 seasons 1 saw, at a distance of from ten to sixteen miles 

 from the land, straggling parties of Papilio Hector flying low 

 and steadily towards the coast of Ceylon. Their course was 

 nearly due east ; and whilst in sight from the vessel they did 

 not deviate from that direction. It was usually at the end of 

 February that 1 saw them, — at the beginning of the short, 

 calm season between the monsoons. Now, the distance 

 across from India to that part of Ceylon from which these 

 hundreds of butterflies were making could not be less than 

 sixty miles, and it has always been a puzzle to me how these 

 delicate creatures — comparatively powerful as their flight is, 

 undoubtedly — could yet have flown so far without rest. Had 

 resting-places on land been needed, these butterflies might 

 have crossed from the Continent by way of Adam's Bridge, — 

 a long sand-bank bearing a few scattered palm trees, about 

 sixteen miles further north; but they were a long way out of 

 sight of it, and their course was very nearly parallel to it. 

 They must have had full confidence in their powers and 

 resources if they came direct from India; and, if not from 

 that country, whence did they come? I shall be glad to hear 

 what you or your correspondents may think of the application 

 of the resling-on-the-water theory to this case. — E. W. H. 

 Holdsworth ; ' Field ' o/ June 29. 



The paragraph to which my friend Mr. Holdsworth refers 

 is the following. A greater degree of interest attaches to the 

 subject than appears evident on first thought. It certainly 

 opens up the large question of the migration of Lepidop- 

 terous insects, of which I have previously recorded so many- 

 instances. 



Butterjlies Migrating and Settling on the Sea. — I fre- 

 quently go for a sail in the Wash, or Boston Deeps, as it is 

 commonly called, and whilst out occasionally see several 

 large white butterflies (Pieris Brassicae), flying about when a 

 considerable distance from the shore. 1 concluded that their 

 powers of flight were greater than generally supposed, or that 

 they found resting-places on the passing vessels, or the buoys 



