44 



Chapter III, 



SMELL IN INSECTS, 



When a brood of the large tortoiseshell butterfly 

 {Vanessa polychloms) is observed frequenting a row 

 of elm trees, they may all be speedily attracted to a 

 particular branch by putting" a little honey on the 

 leaves, and thus the collector may secure as many as 

 he shall require. This circumstance is to be attributed 

 wholly, as it appears to us, to the acute scent of the 

 insects, who no doubt mistake it for some melliferous 

 flower. We have observed, indeed, that butterflies of 

 all species, though far from being voracious feeders, 

 will often dart down from a considerable height upon 

 a flower beneath their track, even when their leading 

 object seemed to be very different from searching for 

 food. This struck us more particularly in a narrow 

 garden at Havre de Grace, enclosed with stone walls 

 fifteen feet high ; for no butterfly, in passing over it, 

 omitted to descend for the purpose of visiting the 

 blossoms of an alpine bluebottle {Centaurea mon- 

 tana), whose smell, however, to our organs, is far 

 from being powerful enough to be perceived at the 

 distance of one foot, much less at fifteen or twenty 

 feet, as it must have been by the butterflies ; for we 

 often saw the painted lady (Cynthia Cardui), and 

 other highflying species, alight there*. These facts 

 will appear more remarkable, if we believe, with 

 M. Le Cat, — though he gives no reason for his 

 opinion, but puts us ofl* with a simile — that odours, 



* J. R. 



