78 Annals Entomological Society of America [Vol. XIII, 



The sexes are easily distinguished as soon as pupation occurs. 

 The lamellate club of the antennae in most species is larger in the 

 male than the female, and thus affords one means of determina- 

 tion. However, this offers some difficulty in species where size 

 differences are not pronounced. In such instances, a second 

 and more reliable method can be adopted. On the ventral 

 surface of the female pupa, immediately cephalad to the anal 

 slit, are two elevated subquadrate structures (Plate II, Fig. 10 r) 

 which are characteristic of female pupas. In the male (Plate II, 

 Fig. 11 r) the same structures are present, but lying somewhat 

 between and caudad to them is a third rounded and somewhat 

 conical elevation (Plate II, Fig. 11 t) which is characteristic 

 of all male pupas examined. The sex of L. lanceolata is also 

 determinable by the size and shape of the male and female 

 pup^. 



The anal aperture of the adult beetle developing within the 

 pupa is so opened as to allow the genitalia of both the males and 

 females to protrude enough to be discernable under the pupal 

 skin. They can be seen under and in the near vicinity of the 

 structures described above, which are used in sex determination. 

 All that is needed is a familiarity with the genitalia of the different 

 species. Figure 11-N shows a ventral view of the posterior 

 region of a male pupa of L. crassissima, and Figure 11-0 is a 

 lateral view of the same. In both views the male genital organ 

 can be plainly seen in the region marked "x. " Figure 10-L is a 

 ventral view of the female of the same species, and Figure 10-M 

 is a lateral view. In the female the genital organ may be found 

 somewhat anterior to the two lobular subquadrate structures, as 

 shown in Plate II, Fig. 10-p, or they may lie directly beneath 

 them. 



As stated, the genitalia are only visible . after the body 

 begins to assume its darkened coloration. Records kept 

 during the past summer show this time of coloring to vary, but 

 it is of sufficient duration in a large number of cases to enable 

 determination to be made over the latter half of the pupal 

 period. The pupal period of L. crassissima was found to vary 

 from -16 to 58 days, with an average, for 178 individuals 

 observed, of 30.5 days. The following table shows, in a few 

 individuals observed, the time elapsing between pupation and 

 the date when specific determination was possible, as well as 

 the time during which the genitalia were visible. 



