258 



SANTAREM 



Diptera, and in their flight look Hke animated spindles ; 

 the wings, placed at the fore extremity of the long, 

 horizontally-extended body, moving rapidly and creating 

 the impression of rotary motion. 



Whilst resting in the shade during the great heat of 

 the early hours of afternoon, I used to find amusement 

 in watching the proceedings of the sand-wasps. A small 

 pale green kind of Bembex (Bembex ciliata), was plentiful 

 near the bay of Mapiri. When they are at work, a number 

 of little jets of sand are seen shooting over the surface of 

 the sloping bank. The little miners excavate with their 

 fore feet, which are strongly built and furnished 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 fe- 

 male 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 believe, to take note of the 

 locality, that she may find it again. This done, the busy 

 workwoman flies away ; but returns, after an absence 

 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 be- 

 numbed 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 ; at least 

 in two or three of the galleries which I opened there 

 was only one fly enclosed. 



I have said that the Bembex on leaving her mine took 

 note of the locality : this seemed to be the explanation 

 of the short delay previous to her taking flight ; on rising 

 in the air also the insects generally flew round over the 

 place before making straight ofl. Another nearly allied 

 but much larger species, the Monedula signata, whose 

 habits I observed on the banks of the Upper Amazons, 

 sometimes excavates its mine solitarily on sand-banks 

 recently laid bare in the middle of the river, and closes the 

 orifice before going in search of prey. In these cases the 

 insect has to make a journey of at least half a mile to pro- 



