118 ILLINOIS BIOLOGICAL MONOGRAPHS [118 



Estigmene acraea D. latipennis 



E. congrua Arachnis zuni 

 Diacrisia rubra A. picta 



D. virginica A. confusa Druce 



Family Lithosiidae 



The Lithosiidae are arctian in most particulars and some of the 

 larvae are said to be indistinguishable from that family. When ver- 

 rucae are present, those of the last two thoracic segments are out of 

 line instead of being in definite transverse rows, and usually only one 

 verruca is present between the spiracle and the proleg in addition to 

 the single seta kappa. Of the American forms the writer has seen only 

 species with the armature reduced to single setae and is unable to de- 

 scribe the positions of the verrucae in other genera. 



The arrangement of the setae is similar to that in Noctuidae except 

 in two or three particulars. The Pi group on the mesothorax and 

 metathorax is bisetose and Rho on the first six or eight abdominal seg- 

 ments is bisetose. An additional seta is also present near mu on the 

 abdominal segments but the Pi group consists of only three setae. The 

 crochets are homoideous. The labrum is shallowly concave at tip. 



Hypoprcpia miniata. The three setae composing the Kappa group 

 on the mesothorax placed on one triple chalaza, equidistant from each 

 other and arranged in a horizontal line. 



Illice nexa. The three setae composing the Kappa group on the 

 mesothorax not borne on the same chalaza, theta much farther caudad 

 than kappa and eta, which are close together, kappa farther ventrad 

 than the others. 



Family Syntomidae 



The Syntomidae are differentiated by the single verruca above 

 that of the kappa group on the last two thoracic segments. The only 

 other similar condition is in one genus of Pericopidae but the position 

 of verruca kappa on segment 7 serves to distinguish the latter from this 

 family (Figs. 67, 68). 



Head similar to that of Arctiidae ; front almost an equilateral tri- 

 angle : labrum moderately acute at tip ; secondary setae usually present. 

 Body bearing verrucae, usually well developed. Prothorax with verru- 

 cae rho rudimentary, but those of kappa and Pi groups large ; mesotho- 

 rax and metathorax with all setae above Kappa group forming a single 

 verruca ; Pi normal ; sigma small or wanting. Abdominal segments 1 

 to 8 (Figs. 67, 68) with alpha, beta, rho, kappa, eta, and mu distinct 

 and separate verrucae ; kappa often small, in about the same position 

 on segment 7 as on other abdominal segments ; Pi group also forming a 



