AUGUST 219 



recognise it ; it required the familiar smell to cany 

 conviction. 



Some naturalists incline, without sufficient reason me- 

 thinks, to postulate a sixth sense as guiding animals in 

 their seasonal migration. Birds and fishes are the 

 migrants with which we are most familiar, but Mr. 

 Eagle Clarke has opened a new field of speculation in 

 respect to the movements of winged insects. He spent 

 thirty-one days during the ungenial autumn of 1903 on 

 the Kentish Knock lightship for the special purpose of 

 studying bird-migration. To his great surprise he found 

 that between 8.45 P.M. and midnight on September 22 

 the lantern was surrounded by numbers of flying insects. 

 Among them were several painted-lady butterflies (Van- 

 essa cardui), by no means a nocturnal creature, but one 

 which, it may be remembered, was unusually plentiful in 

 England during that autumn. Now the nearest point of 

 land to the lightship is the Naze, twenty-one miles off. 

 If these insects came from England, they must have 

 flown against an easterly breeze blowing at the time. 

 The nearest land to windward of the lightship are parts 

 of the French and Belgian coasts, respectively forty-eight 

 and fifty-six miles distant. 



Mr. Clarke observed flights of these delicate insects 

 at intervals until September 28. Was this migration 

 fortuitous or deliberate ? If it was involuntary, we might 

 expect to find Irish butterflies blown out upon the 

 Atlantic. At all events, the nocturnal movement of 

 companies of butterflies is a phenomenon not previously 

 recorded. 



