LEPIDOPTERA 



579 



In order to make use of the primary and subprimary setee in 

 classification, it is necessary that each of these setag should be desig- 

 nated by a distinctive term. The terminology most generally used 

 is that proposed by Dyar ('94), who was the first author to base a 

 classification of lepidopterous larvae on the variations in the arrange- 

 ment of the setiferous tubercles. 



The terminology of Dyar was based on a study of the tubercles 

 of the abdominal segments. He recognized on each side of each ab- 

 dominal segment, except the last two, eight tubercles, which he 

 nimibered with Roman numerals beginning with the one nearest the 

 middle line of the back; the number VII was applied to a group 

 of three tubercles on the outside of the proleg, or in a corres- 

 ponding position in the legless abdominal segments. Subsequent 

 studies, and especially those by 

 Forbes ('10) and Fracker ('15), 

 have revealed the presence of 

 setiferous tubercles not num- 

 bered by Dyar. Figure 717,6, 

 represents the arrangement of 

 the tubercles of a middle ab- 

 dominal segment of a noctuid 

 larva as figured by Forbes. The 

 tubercles are numbered ac- 

 cording to the terminology of 

 Dyar, with the addition of 

 tubercles X, Ilia, and IX, not 

 figured by Dyar.* 



The arrangement of the 

 setiferous tubercles on the 

 thoracic segments of any cater- 

 pillar differs to a considerable 

 extent from that on the ab- ^^2- 717— Arrangement of setiferous tu- 

 J -1 ^ r ji bercles m a noctuid larva: a, tubercles 



dommal segments of the same ^f ^ metathorax; b, tubercles of a 



insect. In Figure 717, arepre- middle abdominal segment. (After 



sents the arrangement of the Forbes.) 



tubercles on the metathorax and h that of the tubercles of a middle 

 abdominal segment of a noctuid larva as figured by Forbes ('10). 

 This writer also figures and numbers the setae on the head of a 

 caterpillar. 



Fracker ('15) made an extended study of the classification of 

 lepidopterous larvae, which was based quite largely on the variations 

 in the number and positions of the setiferous tubercles; and his 

 paper is illustrated by a large ntmiber of setal maps. This writer 

 proposes a mcw terminology for the setae, using Greek letters instead 

 of Roman nimierals. 



*In diagrams indicating the arrangement of setiferous tubercles, one side of a 

 single segment is represented as if cut on the mid-dorsal and mid-ventral lines, 

 and laid fiat. The anterior edge is to the left, and the mid-dorsal line at the up- 

 per edge. In Figiu-e 717 the positions of the spiracle and of the legs are also 

 indicated. 



