SCELIPHRON AND ITS PREY 



297 



It is quite extraordinary to think that all that material, 

 weighing perhaps half a pound, has been brought by 

 one insect. 



The destruction of spiders wrought by one Sceliphron 

 in providing for a future generation is also surprising. 



On Kerenge Isle I counted the number taken from 

 twenty -nine cells. In the following table a cell is indi- 

 cated by a serial number, and all cells found attached 

 together, i.e. built by one individual, are indicated by 

 the same letter. 



lA 

 2A 

 3A 

 4B 

 6B 

 6C 

 7C 

 SD 

 9D 

 lOD 



} 



7 

 9 

 11 

 14 

 12 

 15 

 11 

 11 

 19 



The average number of spiders in a cell was 9-3, the 

 minimum one, the maximum nineteen. The variation 

 in the amount of food stored up is considerable, even in 

 cells constructed by one Sceliphron. Thus No. 6 had only 

 a single spider, very little larger than one of the seven 

 in cell No. 7. The spiders are usually of a number of 

 different species, but the twelve in cell No. 19 appeared 

 to be the same. 



The destruction of spiders by Sceliphron must be con- 

 siderable. Supposing that ten cells are completed during 

 the lifetime of one individual, it will have accounted for 

 about ninety spiders. 



Sceliphron itself, however, is victimized by a large 

 " Ichneumon " fly of the same black and canary -yellow 

 hues presenting a remarkable likeness to its victim, 

 especially when seen on the wing at a little distance. 

 Two- winged flies (Tachinidae) can also be reared from 



