296 HYI^IENOPTERA 



completed cell is about an inch and a half long, thick 

 walled and smooth, with an internal calibre of an ordinary 

 lead pencil. It is stuffed full of small paralysed spiders, 

 on one of which the elongated egg has been deposited. 



The Sceliphron obtains its building material from a 

 spot where the earth is damp, such as the edge of the 

 lake, and gathers up in her mandibles a pellet about the 

 size of a sweet-pea seed. With this she at once flies back 

 to the chosen spot, and plasters it on to one end of the 

 commenced cell, smoothing it with her mandibles very 

 deftly, singing the while her high-pitched working song. 



No sooner has she used up the pellet than back she 

 goes for another, until the cell is completed, save for the 

 closing of one end, which is done when the stock of spiders 

 has been brought. 



On Kerenge Isle, where spiders were exceedingly 

 abundant, Sceliphron was also plentiful, and my grass 

 hut was a very favourite nesting place, so that the high- 

 pitched song of the worker was heard all day long. While 

 sitting writing one morning I timed the journeys of one 

 individual, noting the moment when she reappeared with 

 a fresh pellet of moist building material, which she applied 

 without waste of time, flying away again immediately to 

 bring another pellet. 



The following are the times noted : 8- 45, 8- 48, 8- 50^, 

 8-57i 91, 9-6, 9-8i, 912J, 917, 923^ 927, 930, 9-33J, 

 9-36^ 9-39^ 9-41J, 944^, 9-47. After this she did 

 not reappear for half an hour, and I went out. 



The average time taken to fly from the nest to the 

 lake shore, collect a mud pellet, bring it back, and build 

 it on to the nest was 36 minutes, the shortest being two 

 minutes, the longest seven. 



Although the cells are often built singly, they may 

 be aggregated, being built one alongside the other, so 

 that a single mass the size of a small fist may be formed, 

 comprising eight or ten cells, each stuffed with spiders. 



