4 WHEELER— THE PARASITIC ACULEATA. 



detcrsa of Australia and subrixafor of the Philippines. In both 

 species the female, though possessing a well-developed sting, has 

 13-jointed antennae, a number peculiar to the male in all other bees 

 and in fact in most other Aculeates. The specimens cannot be 

 gynandromorphs, because R. E. Turner found the 13 joints in 14 

 females of detersa, so that Cockerell is justified in regarding it as 

 " certain that this is a normal condition and must represent an early 

 stage in the evolution of a parasitic species, like those of Ccclioxys 

 and Stelis. From the standpoint of genetics, it is an extraordinary 

 case, since the female seems to have dropped her secondary sexual 

 characters and thereby assumed those of the male which were pres- 

 ent in her genetic constitution." He adds that " presumably the 

 male of A. suhrixator cannot be distinguished from Mcgachile 

 suhrixator," which is a common species in the Philippines and in all 

 probability the host. 



Another peculiarity of the parasitic bees, to which Friese has 

 called attention, is their often very vivid coloration. Many of the 

 species are more or less red or yellow {Sphccodcs, Nomada, Epeo- 

 his, etc.) or banded and spotted with patches of white or blue 

 appressed hairs or scales {Epeolus, Crocisa, M electa, etc.), or are 

 brilliantly metallic (Excerete, Aglac). The red color suggests that 

 of certain myrmecophilous beetles {Eomcchusa, Hetccrius, Clavigcr, 

 etc.) and may have a similar meaning, but it is difficult to account 

 for the spots and bands unless we assume that they are an expres- 

 sion of peculiarities of metabolism, associated with the active habits 

 of the parasites, an interpretation which has also been suggested to 

 account for the more vivid color patterns of the males as contrasted 

 with the cospecific females of many animals. Perhaps the pecu- 

 liar odors of certain parasitic bees, c. g., of Nomada, odors which in 

 some cases at least seem to play a role in the relations to the host, 

 also point to such peculiarities in metabolism. 



From an examination of the brains of two genera of parasitic 

 bees, Nomada and Psithyrus, von Alten (1910) concluded that 

 their fungiform bodies, supposed to be the seat of intelligence and 

 therefore to correspond to our cerebral hemispheres, were more 

 feebly developed than in the nonparasitic species. He even found 

 that the fungiform bodies of the male parasites were relatively 



