122 ILLINOIS BIOLOGICAL MONOGRAPHS [122 



ee. Abdominal segments not bearing intersegmental stripes but 

 seoli Rho and Kappa connected by a yellowish ridge ; 

 spiracle about half way between scoli Rho and Kappa. 



Telea 



bb. Scoli alpha of mesothorax and metathorax larger than those of 



abdominal segments 2 to 6. 



c. Abdominal segments 1 and 2 bearing two scoli below spiracle ; 



scoli alpha of first abdominal segment much larger than those 



of second. Samia 



cc. Abdominal segments 1 and 2 bearing one scolus or none below 



spiracle, or sometimes a second one, very rudimentary ; scoli 



alpha of first abdominal segment not much larger than those 



of second. Callosamia 



aa. Eighth abdominal segment not bearing a scolus on the dorsomeson. 



b. Secondary setae numerous and long, obscuring the scoli, which are 



reduced. Agapema 



bb. Secondary setae rare or absent; scoli conspicuous, subequal in 



size on all segments. Saturnia 



Genera of Hemileucidae : 



a. Lateral spinules of supraspiracular scoli rho usually sparse, not 

 obscuring axis of scolus; head smaller than prothorax; secondary 

 setae often numerous ; labrum shallowly notched, 

 b. Scoli alpha of abdomen modified into verricules strikingly different 

 from other scoli. 

 c. Body covered with small white dots, each dot surrounding the 

 base of a secondary seta; colors variegated. Hemileuca 



cc. Body not covered with white dots, unicolorous (except in 

 P. hera). Pseudohazis 



bb. Scoli alpha of abdomen similar to those of other parts of the 

 body. Coloradia 



aa. Lateral spinules of supraspiracular scoli Rho long, thickly set, ob- 

 scuring axis of scolus ; head larger than prothorax ; secondary setae 

 of body rare ; labrum notched to more than one-half its depth. 



Aidomeris 

 Genera of Ceratocampidae : 



a. Secondary setae numerous, conspicuous, and distinctly longer than 

 scoli of abdomen. Basilona 



aa. Secondary setae above level of prolegs inconspicuous. 



b. Eighth abdominal segment bearing a scolus on the dorsomeson 



(Fig. 110) ; armature of metathorax similar to that of mesothorax. 



c. Prothorax bearing well developed scoli ; abdominal scoli slender, 



echinulate. Cither onia 



