REVISION MALACOSOMA HUBNER IN NORTH AMERICA 37 



usually has a single line which may be more distinct tlian the dorsal 

 one, and which often bends sharply inward near the anterior margin. 



The wing venation (fig. 10) is constant for all species. Only slight 

 individual variations in the point of branching of veins have been 

 noticed except for veins R2 and R3. These veins may vary within the 

 same species frona complete fusion to almost complete separation. 



Color is extremely variable, even within species, ranging from 

 dark chocolate brown to light straw yellow, with all intermediate 

 shades. The body is about the same color as the wings and lacks any 

 distinctive markings. Females are more stout-bodied than males, and 

 have a greater wingspread. The wingspread of females is 25 to 50 mm.; 

 most specimens are 30 to 35 mm. The wingspread of males is 20 to 40 

 mm.; most specimens are 25 to 30 mm. 



The head is densely covered with fine, hairlike scales, and the 

 eyes sparsely so. Ocelli are absent. The antennae are bipectinate, 

 males with rami of medium length, and females with shorter rami, 

 about half as long as those of the males. Mouthparts are absent except 

 for the three-segmented labial palpi. 



The thorax is densely covered with fine, hairlike scales which ob- 

 scure all structures. The tarsi of all legs bear numerous small spines 

 ventrally on all five segments, and the last tarsal segment terminates 

 in a pair of strongly curved claws. The meso- and meta-thoracic tibiae 

 have a pair of short spurs at the tip. Each foreleg usually bears an 

 epiphysis (figs. 75-78) which is more highly developed in males than 

 in females. It is nearly always present in males, but frequendy absent 

 in females. 



The abdomen is moderately densely covered with scales and hairlike 

 scales; the tip of the male abdomen is rather blunt and tufted with 

 long hairlike scales, while the abdomen of the females is much heavier, 

 more evenly rounded at the tip, and without tufts of scales. The first 

 segment of the abdomen is somewhat reduced, segments 2-6 are 

 "normal," and the terminal segments are modified to form the genitaha 

 and accessory structures. Spiracles are present on segments 1-7. 

 The tergites and sternites are moderately sclerotized, and tergites 

 2-7 of females have a median unsclerotized area which is most pro- 

 nounced on segments 3-6. 



Male Terminalia 



The male terminalia of Malacosoma (fig. 30) have been highly 

 modified, yet they retain the fundamental plan of male lepidopterous 

 structure. 



