2 BULLETIN 143, UNITED STATES NATIONAL MUSEUM 



The classifications that have thus far been proposed for the Mutil- 

 lidae have had a purely morphological basis, and the problem has 

 been approached by most workers with the idea that the family is an 

 exceedingly variable group. Recent study has shown that in the case 

 of many American sj)ecies, at least, this idea has originated from the 

 fact that series of specimens in collections supposed to represent a 

 single species were really composite and represented two or more 

 species. Even from the strictly morphological viewpoint many val- 

 uable structural characters which have specific and possibly generic 

 or higher value have been completely overlooked. The classification 

 and phylogeny of the Mutillidae is still very obscure, due to the fact 

 that the morphological basis on which the former has been erected is 

 ver}^ incomplete, and also to the fact that morphology alone is too 

 inadequate a basis for a natural classification. 



A true phylogeny of any group of organisms represents the rela- 

 tionships of the component parts of the groups and also represents 

 the course of evolution during their development in geologic time. 

 The relationships of groups of organisms as they have actually 

 existed during the course of evolution can only be completely under- 

 stood when all the facts regarding them are available, and the phy- 

 logeny representing all these developments may be referred to as the 

 "ideal phylogeny." The nearer a classification of a group of or- 

 ganisms can approach to expressing this ideal phylogeny, the more 

 natural it will be, and the nearer it will come to expressing true 

 relationships. 



The factors of phylogeny are morphology, physiology, ontogeny, 

 and ecology. All of these factors have expressed themselves in all 

 organisms and the ideal phylogeny is the sum of this expression. A 

 classification based on morphology alone is then obviously incom- 

 plete since it ignores the facts of physiology, ontogeny, and ecology. 

 In other words, the biological data which will reveal some knowl- 

 edge regarding the relationships of the organisms in question have 

 been neglected. 



As mentioned above, the classifications of the Mutillidae so far 

 proposed have been based almost entirely on morphological grounds. 

 This is not surprising in view of the fact that comparatively little is 

 known regarding the biology of the family as a whole and the 

 knowledge that we do possess is widely scattered through the litera- 

 ture and more or less inaccessible. In order to overcome the latter 

 difficulty the writer has attempted to bring together in the following 

 pages all the facts available regarding the biology of this interesting 

 family of wasps. It is believed that a summary of this sort will not 

 only serve to stimulate further investigation of the group, but will 

 also be of some material aid in any phylogenetic study of the family 

 that mav be undertaken. 



