Walter] 



CLASPING ORGANS IN HYMENOPTERA 



81 



amply sufficient for the determination of the families. Nor can 

 peculiarities of the clasping arrangement be used for differentiating 

 nearly related genera similar in their grosser characters, because 

 such nearly always agree in the character of their clasping organs. 

 Neither does the structure of the clasping apparatus admit of the 

 recognition of the different sexes of the same species, males and 

 females showing the greatest similarity in this respect. At the most, 

 the larger females possess more hooks than the smaller males (Bom- 

 bus, Camponotus, Vespa). The number of the hooks, of the distal 

 as well as the subbasal rows, is by no means constant and character- 

 istic for any one species, but varies more or less with the size of the 

 animal, between very wide limits. Of a number of species it may be 

 said that the number of the hooks is primarily in accordance with the 

 size and not with the power of flight. The great variability in the 

 number of hooks, which precludes their utilization in systematic 

 work, may be shown by the following table, in which the results of 

 counting the number of hooks in different specimens of three species 

 are brought together (/. — left; r. — right wing) : 



Rhyssa persuasoria L. 

 I. r. 



SbH. D H. 

 11 

 12 

 13 

 14 

 15 

 16 

 16 



(All the specimens of Vespa rufa were taken from the same nest.) 



This table shows how wide the limits of variation are in this 

 respect, even in a comparatively small number of individuals of 

 the same species. It also shows that usually even the same indi- 

 vidual has different numbers of hooks on the right and the left hind 

 wing. A repetition of the same numbers in different specimens turns 

 out to be still more rare, and was only found once in Vespa rufa 

 6 



