230 



HUBERT M. MORRIS. 



and occasional ones on other segments, which bear a single, short, blunt spine. The 

 scales in this larva are much more regular and are placed more closely together than 

 in any other species so far examined (fig. 15). 



Fig. 15. Portion of cuticle of larva of 



Bibio venosus from dorsal surface of fourth 



segment : a, lateral view ; b, vertical view ; 



X 330. 



Pupa. 



This pupa again bears a considerable resemblance to that of B. marci, from which 

 it also differs in its smaller size ; in the greater development of the process at the 

 anterior end, which is slightly larger than that of B. lacteipennis ; and in the 

 presence in the male of a pair of similar blunt processes on the anterior portion 

 of the eyes. The eyes in the male of this species are rather smaller than in the 

 two species previously described. Length of pupa 10 to 11-5 mm. In the 

 laboratory the pupal state lasted 19 days. 



Differences between Larvae of various Species. 



In the foregoing descriptions of Bibio larvae it will be noticed that attention 

 is drawn to the differences in the cuticular structures in the different species dealt 

 with. These differences seem so far to be sufficiently cHstinct and regular to give 



ilOAIM /' 



— O ^„ O ^^ 



Fig. 16. Portion of cuticle of larva of Bibio johannis from 



dorsal surface of fourth segment : a, lateral view ; 



b, vertical view ; x 330. 



a ready means of distinguishing between the species in the larval state. There 

 are many other species of Bibio, the larvae of which have not yet been examined, 

 but it is possible that some such distinction may hold good throughout. 



