INSTINCT OF LOCALITY 259 



cure the kind of fly, the Motuca (Hadaiis lepidotus), with 

 which it provisions its cell. I often noticed it to take a 

 few turns in the air round the place before starting ; on 

 its return it made without hesitation straight for the closed 

 mouth of the mine. I was convinced that the insects 

 noted the bearings of their nests and the direction they 

 took in flying from them. The proceeding in this and 

 similar cases (I have read of something analogous having 

 been noticed in hive-bees) seems to be a mental act of the 

 same nature as that which takes place in ourselves when 

 recognizing a locality. The senses, however, must be im- 

 measurably more keen and the mental operation much 

 more certain in them than it is in man ; for to my eye there 

 was absolutely no landmark on the even surface of sand 

 which could serve as guide, and the borders of the forest 

 were not nearer than half a mile. The action of the wasp 

 would be said to be instinctive ; but it seems plain that 

 the instinct is no mysterious and unintelligible agent, 

 but a mental process in each individual, diflering from 

 the same in man only by its unerring certainty. The 

 mind of the insect appears to be so constituted that the 

 impression of external objects or the want felt, causes it 

 to act with a precision which seems to us like that of a 

 machine constructed to move in a certain given way. I 

 have noticed in Indian boys a sense of locality almost as 

 keen as that possessed by the sand-wasp. An old Portu- 

 guese and myself, accompanied by a young lad about 

 ten years of age, were once lost in the forest in a most 

 solitary place on the banks of the main river. Our case 

 seemed hopeless, and it did not, for some time occur to us 

 to consult our little companion, who had been playing 

 with his bow and arrow all the way whilst we were hunting, 

 apparently taking no note of the route. When asked, 

 however, he pointed out, in a moment, the right direction 

 of our canoe. He could not explain how he knew ; I 

 believe he had noted the course we had taken almost un- 

 consciously : the sense of locality in his case seemed 

 instinctive. 



The Monedula signata is a good friend to travellers in 

 those parts of the Amazons which are infested with the 

 blood-thirsty Motuca. I first noticed its habit of preying 

 on this fl}' one day when we landed to make our fire and 

 dine on the borders of the forest adjoining a sand-bank. 

 The insect is as large as a hornet, and has a most waspish 



