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12 BULLETIN 143, UNITED STATES NATIONAL MUSEUM 



It is remarkable that the hosts of only 39 species of Mutillids are 

 known, in view of the fact that the number of species of the latter 

 that have been described runs into the thousands. The knowledge 

 that we have of this phase of Mutillid biology is most meager, and the 

 need for further investigation is apparent. It is probable that many 

 species of these wasps may have some economic importance, as in 

 the case of the three species attacking the tsetse fly. It can also be 

 predicted with certainty that as a more complete knowledge of the 

 host relationships of the Mutillids is gained, more facts regarding 

 the phylogeny of the group will be brought to light. 



The possibilities as to the range of the host relationships is more 

 or less unlimited on account of the little information that is known. 

 Thus it may be that many Coleoptera serve as hosts for Mutillids 

 (s. str.) in addition to the Ciythrid beetles mentioned in the table. 

 The validity of this relationship seems to be fairly well established, 

 having been observed by two different workers. It is quite improb- 

 able that Glossina 7norsitans Westwood is the onl}^ dipterous insect 

 involved as host, and as our knowledge becomes more complete many 

 other Diptera will likely be shown to be hosts of these insects. It 

 is interesting to note at this point that Lamborn (1925) has suc- 

 ceeded in rearing MutlUa glossinae from the pupae of Sarcophagid 

 flies. Previously this species had been known to parasitize only 

 Glossina morsitans. Lamborn states that seven male Mutillids were 

 reared from 10 Sarcophagid puparia which were submitted to a 

 female Mutilla glossinae. Whether other orders of insects than the 

 Coleoptera, Diptera, and Hymenoptera serve in this relation it is 

 impossible to say. 



Even among the h^^menopterous hosts the information available is 

 often vague and sometimes doubtful. It must be borne in mind 

 that the relationships as tabulated above are not definitely established 

 in every case. In some instances the identification of the Mutillid 

 appears to be incorrect, and the possibility exists that the host may 

 be incorrectly identified since the records are not all based on rearing 

 experiments carefully carried out. 



Two conclusions may be drawn from this tabulation : (1) A single 

 species of Mutillid is not limited to a single species or genus of 

 Hymenoptera or Diptera for a host ; this is clearly shown in the case 

 of Mutilla europaea Linneaus and DasymutUla hioculata (Cresson). 

 However, in the latter instance the two genera which serve as hosts, 

 Bemhia; and Aficrohemhex, are very closely related; (2) a single 

 species of the host insect may be the host of more than one species of 

 Mutillid. This is established in the case of Glossina morsitans 

 Westwood, but has not been demonstrated in the case of the hymenop- 

 terous hosts. 



