THE NATURALIST ON THE RIVER AMAZONS. 



'.In the dry season when the brisk east wind 

 is blowing, and the sharpness of outline of 

 hills, woods, and sandy beaches, give a great 

 charm to this spot. 



While resting in the shade during the great 

 heat of the early hours of afternoon, I used 

 to find amusement in watching the proceed- 

 ings of the sund wasps. A small pale green 

 kind of Bembex (Bembex ciliata) was plenti- 

 ful near the bay of Mapiri. When they are 

 at work a number of little jets of sand are 

 seen shouting over the surface of the sloping 

 banks. The little miners excavate with their 

 fore feet, which are strongly built and fur- 

 nished with a fringe of stiff bristles ; they 

 work with wonderful rapidity, and the sand 

 thrown out beneath their bodies issues in 

 continuous streams. They are solitary wasps, 

 each female working on her own account. 

 After making a gallery two or three inches 

 in length, in a slanting direction from the 

 surface, the owner backs out and takes a few 

 turns round the orifice, apparently to see 

 whether it is well made, but in reality, I be- 

 lieve, to take note of the locality, that she 

 may find it again. This done the busy work- 

 woman flies away ; but returns, after an ab- 

 5 sence varying in different cases from a few 

 minutes to an hour or more, with a fly in her 

 grasp, with which she re enters her mine. 

 On again emerging the entrance is carefully 

 closed with sand. During this interval she 

 has laid an egg on the body of the fly, which 

 she had previously benumbed with her sting, 

 and which is to serve as food for the soft 

 footless grub soon to be hatched from the 

 egg. From what I could make out the 

 Bembex makes a fresh excavation for every 

 egg to be deposited ; e.t least, in two or three 

 of the galleries which I opened there was 

 only one fly inclosed. 



I have said that the Bembc^ on leaving 

 her mine took note of the locality : this 

 seemed to be the explanation of the short de- 

 lay previous to her taking flight ; on rising 

 ^in the air, also, the insects generally flew 

 round over the place before making straight 

 off. Another nearly allied but much larger 

 species, the Monedula signata, whose habits 

 I observed on the banks of the Upper Ama- 

 zons, sometimes excavates its mine solitarily 

 on sand- banks recently laid bare in the mid- 

 dle of the river, and closes the orifice before 

 going in search of prey. In these cases the 

 insect has to make a j jurney of at least half 

 a mile to procure the kind of fly, the Motuca 

 (Madrus lepidotus), with which it provisions 

 its cell. I often noticed it to take a few 

 turns in the air round the place before start- 

 ing ; on its return it made without hesitation 

 straight for the closed mouth of the mine, i I 

 was convinced that the insects noted the bear- 

 ings of their nests, and the direction Ihey 

 took in flying from them. The proceeding 

 in this and similar cases (I have read of some- 

 thing 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 immeasurably more keen) 

 and the mental operation much more certain, 

 in them than they are in man ; for to my eye 

 there was absolutely no land-mark 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, differing from the same 

 in man only by its unerring certainty. The 

 mind of the insect appears to be so constitut- 

 ed 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 away. 

 I have noticed in Indian boys a sense of 

 locality almost as keen as that possessed by 

 the sand- wasp. An old Portuguese and my- 

 self, 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 con- 

 sult our little companion, who had been play- 

 ing with his bow and arrow all the way 

 while we were hunting, apparently taking no 

 note of the route. When asked, however, 

 he pointed out, in a moment, the right direc- 

 tion of our canoe. He could not explain how 

 he knew ; I believe he had noted the course 

 we had taken almost unconsciously. 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 by the bloodthirsty 

 Motuea. I first noticed its habit of preying 

 on this fly 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 appear- 

 ance. I was rather startled when one out of 

 the flock which was hovering about us flew 

 straight at my face : it had espied a Motuca 

 on my neck, and was thus pouncing upon it. 

 It seizes the fly not with its jaws, but with 

 its fore and middle feet, and carries it off 

 tightly held to its breast. Wherever the 

 traveller lands on the Upper Amazons in the 

 neighborhood of a sand-bank he is sure to be 

 attended by one or more of these useful ver- 

 min killers. 



The bay of Mapiri was the limit of my day 

 excursions by the river-side, to the west of 

 Santarern. A person may travel, however, 

 on foot, as Indians frequently do, in the dry 

 season for fifty or sixty miles along the broad 

 clean sandy beaches of the Tapajos. The 

 only obstacles are the rivulets, mast of which 

 are fordabfe when the waters are low To 

 the east my rambles extended to the banks of 

 the Mahica inlet. This enters the Amazons 

 about three miles below Suntarern, where the 

 clear stream of the Tapajos begins to be dis- 

 colored by the turbid waters of the main 

 river. The Mahica has a broad margin of 

 rich level pasture, limited on each side by the 



