REVISION MALACOSOMA HUBNER IN NORTH AMERICA 189 



of calif ornicum. Larvae of neustrium are separated easily from americanum 

 by the presence of a conspicuous pair of black dorsal humps on abdom- 

 inal segment eight. In addition, the average number of setae in setal 

 group Dl is four and in setal group L2 is two on abdominal segments 

 3-6 for neustrium. M. disstria is the only North American species with 

 setal counts like this. All other North American species average five 

 setae in Dl and three in L2. Only a few inflated larvae of castrensis 

 (sLx) and franconicum (one) have been available, but these specimens 

 have mottled blue and black heads. This immediately distinguishes 

 them from americanum which has a black head. The number of setae in 

 setal group L2 averaged three for castrensis and franconicum, which is 

 the same as all species except disstria and neustrium. The number in Dl 

 was usually sLx for castrensis and five or six for franconicum, which is 

 greater than the four or five found in other species. 



Adults of both neustrium (figs. 321-323, 324, and 327) and castrensis 

 (figs. 325 and 326) are reported to be as highly variable as the North 

 American species, with colors ranging from pale yellow to dark reddish- 

 brown, and with variable lines on the forewings, or rarely none at all. 

 Adult franconicum (figs. 328 and 329) apparently are not as highly vari- 

 able, and they are unusual in having somewhat transparent wings, with 

 clearly outlined veins covered by dark scales, and in having no lines 

 on the forewings or relatively indistinct ones. 



Adult male neustrium easily can be identified by their large, distinctive 

 epiphysis which is like that of North America's disstria (fig. 75). The 

 epiphysis of male castrensis and franconicum is either small or absent. 

 However, the male terminalia of neustrium (figs. 27, 52, and 72) are 

 closer to those of castrensis (figs, 28, 53, and 73) and franconicum (figs, 

 29, 54, and 74) than they are to those oi disstria (figs. 12, 37, and 57), 



The few male castrensis which have been examined can be separated 

 from male franconicum which have been examined by their small 

 epiphysis (absent or minute on franconicum) or by genitalic differences 

 (relatively slight and of unknown constancy), but they are most easily 

 separated by the differences in wing scales which are more fully 

 discussed in the next paragraphs on females. 



The female terminalia of all three Palearctic species are quite 

 similar. The genital plate is unsclerotized except for a narrow arch 

 just anterior to the ostium. The ovipositors of all three species are 

 virtually identical, and differ from all North American species by 

 lacking a distinct ventral lobe in combination with a pronounced 

 dorsal lobe (fig, 104), The ovipositor is relatively small when compared 

 with those of North American species, and is closest to that of M. 

 tigris (fig. 84) in size and shape. 



279-280—68 14 



