87 



Family Pieridae 



The pupae of this family resemble the Papilionidae very strongly 

 as to the general shape of the body and arrangement of ridges and 

 projections. They are much smaller, however, and are easily recog- 

 nized by the fact that they possess a single median cephalic projection 

 instead of two cephalo-lateral projections as do the Papilionidae. The 

 epicranial suture is never present. The labrum is usually slightly 

 cephalad of its normal position and a small portion of the labial palpi 

 is always exposed. The maxillae vary in length from two thirds the 

 length of the wings to extending slightly beyond their caudal margin. 

 The legs are of normal length. The antennae are more distinctly 

 clubbed than in the Papilionidae and sometimes reach the caudal mar- 

 gin of the wings. The caudal end of the body is very like that of the 

 Papilionidae except that the four ridges are seldom present, and the 

 hooked setae are inserted in a slight concavity. The genital openings 

 are in the usual positions. On the ventral surface of the tenth abdom- 

 inal segment there is a low ridge, circular in outline, which encloses 

 the anal opening and terminates at its cephalic end in a small tubercle 

 on each side of the meson. These tubercles are located just caudad 

 of the genital openings. Similar tubercles and ridges are found in the 

 Nymphalidae, but they are rather more prominent in that family. 

 Tubercles without the ridges occur in the Papilionidae. 



There is very little question as to whether or not the Pieridae 

 and Papilionidae are related, but which is the more specialized seems 

 to be a questionable point with all workers in the group. Aside from 

 the question of prominences or projections, which, after all, seems a 

 matter of small importance, there is little of fundamental difference 

 between the two families excepting the length of the thoracic seg- 

 ments, which are more generalized in the Papilionidae, and the ridges 

 and tubercles just mentioned on the ventral surface of the Pieridae, 

 which resemble the Nymphalidae. The Nymphalidae certainly seem 

 to be the most specialized of the Papilionoidea, although this is an- 

 other much debated question. The two families have undoubtedly 

 been developed from a common ancestor and represent parallel lines 

 of development. The genera of Pieridae may be separated by the 

 following table : 



a. Distance from the cephalic margin of the prothorax to the distal end 

 of the cephalic projection much less than the length of the pro- 

 thorax ; ventral line of body often convex but never forming a prom- 

 inent angle. 



b. Thorax with a strongly carinate median ridge, highest at the mid- 

 dle of the mesothorax, and forming a prominent projection; ab- 



