A Comparison of the Male Genitalia of Cane 



Beetles. 



AVorking with other groups of insects,, I learned hoAV useful were 

 the chitinous parts of the male intromittent organ for specific determina- 

 tion. Unfortunately, I have not recenth^ had access to papers by Forbes 

 and others, who used such characters for separating the Scarabieida?. 

 Yet, with the tremendous variety of these beetles occurring in Australia, 

 it is frequently a rather difficult matter to separate species on other 

 external characters. A case in point is Lcpidiota consohrina Girault, 

 which was confused for some time with L. frcncJti Blackburn. The 

 grubs of the two species were easily distinguishable, and ^Ir. Dodd (91) 

 cleared the matter up by breeding them out. when he discovered some 

 slight differences in the adults. Keferring to Plate XYI, however, it 

 will be noted that the genitalia of these two species bear little 

 resemblance. And, again, the adults of Lepidiota rotJiei Blackljurn and 

 L. No. 215 are very similar in appearance, but it will be seen that they 

 are easily separated by referring to these characters. 



Watching mating beetles, I first observed the pouch-like bursa 

 (Plate XVI, fig. 4, aa) extending from the end of the penis, just as 

 they separated. In a moment, however, this was retracted within the 

 chitinous structure. Apparently this bursa fits inside the Ijursa 

 co'pulatrix of the female during mating. At any i-ate it has exactly the 

 same form and size, the surface being covered witli exceedingly small 

 hairs. 



I have only had time to touch upon this systematic phase of the 

 problem, but undoubtedly its possibilities are many for exact 

 determination of species. 



