4 BULLETIN 143, UNITED STATES NATIONAL MUSEUM 



sisted of only males and females, or whether workers were also 

 present as in the social insects. 



Champion (1836) was the first to suggest that the Miitillids were 

 parasites of other wasps and bees. He gives his reasons for such a 

 conclusion, as follows : " I have frequently seen the females enter 

 the nests of Andrenidae, and occasionally those of CerceHs. I also 

 once caught a female climbing the trunk of Uhnus campestris, on 

 which some of the Eutnenes had formed their clay bottle-shaped 

 nests. Another species I took commonly on the sea sand, in which 

 the Bemhex rostrata had dug its nests." Shuckard (1837a) believed 

 that possibly the larva was fed on Diptera, because " my friend, 

 Mr. Pickering, dug a female out of the ground during the last winter 

 at Coombe wood, and mixed in the sand he had removed he found 

 the wings of flies." This, of course, has never been confirmed, since 

 none of the Mutillids, either in the larval or adult state, are known 

 to feed on adult insects. Nylander (1846) reports that Dahlbom 

 had collected M. europaea in the nests of Botiibus rajeUus Kirby, 

 but makes no other comment regarding it, and Dahlbom (1847) 

 himself called attention to this same fact and suggested that the 

 Mutillid was really a parasite. 



The various textbooks on entomology of this period and even as 

 late as 1860 quote various of the above-mentioned authors regarding 

 the habits of the Mutillids, but in most of these the suggestions 

 regarding the parasitic role of these wasps were ignored. 



OBSEKVATIOXS ESTABLISHING THE PARASITIC RoLE OF THE MUTILLIDS 



Over 50 years after Christ made his observations regarding the 

 relationships of bumblebees and Mutillids, Drewsen (1847) estab- 

 lished the fact that this relationship was parasitic. Even Drewsen 

 calls attention to the fact that Christ's statements had been prac- 

 tically neglected during this 50-year period by the entomologists 

 who wrote on the subject of Mutillids. Drewsen collected a nest of 

 the bumblebee Bomhus scrwishiranus Kirby and took it home for 

 observation. The nest contained over 100 cells, but he obtained only 

 two worker bumblebees from it. In addition to these, however, he 

 reared 44 males and 32 females of 31. eujvpaea from the nest. He 

 observed that the cells from which he obtained the Mutillids had 

 been closed after the bumblebee larvae were full grown and that, 

 therefore, the former must have destroyed the full-grown bumble- 

 bee larva and in its turn have become the occupant of the cell. It 

 was also his opinion that the ovipositor of the Mutillid served as an 

 apparatus to bore through the wall of the cell and either kill or 

 arrest the development of the bumblebee larva. 



This was the first step in advance that the biology of the Mutillids 

 had taken since the work of Christ. It clearly established the para- 



