234 SOCIAL LIFE IN THE INSECT WOULD 



how far we do not know. The Necrophori, in quest 

 of a place where to establish their family, travel great 

 distances to find the corpses of small animals, informed 

 by such odours as offend our own senses at a con- 

 siderable distance. 



The Hydnocystis, the food of the Bolboceras, emits 

 no such brutal emanations as these, which readily diffuse 

 themselves through space ; it is inodorous, at least to 

 our senses. The insect which seeks it does not come 

 from a distance ; it inhabits the places wherein the 

 cryptogam is found. Faint as are the effluvia of this 

 subterranean fungus, the prospecting epicure, being 

 specially equipped, perceives them with the greatest 

 ease ; but then he operates at close range, from the 

 surface of the soil. The truffle-dog is in the same 

 case ; he searches with his nose to the ground. The 

 true truffle, however, the essential object of his search, 

 possesses a fairly vivid odour. 



But what are we to say of the Great Peacock moth 

 and the Oak Eggar, both of which find their captive 

 female ? They come from the confines of the horizon. 

 What do they perceive at that distance ? Is it really an 

 odour such as we perceive and understand ? I cannot 

 bring myself to believe it. 



The dog finds the truffle by smelling the earth quite 

 close to the tuber ; but he finds his master at great 

 distances by following his footsteps, which he recognises 

 by their scent. Yet can he find the truffle at a hundred 

 yards ? or his master, in the complete absence of a trail ? 

 No. With all his fineness of scent, the dog is incapable 

 of such feats as are realised by the moth, which is em- 

 barrassed neither by distance nor the absence of a trail. 



