REVISION MALACOSOMA HUBNER IN NORTH AMERICA 45 



adjacent areas are black. Often the black around Dl may extend 

 ventrally to just below setal group SD, resulting in a mark that is 

 referred to as the "vertical black bar" (figs. 7 and 376). The dorsal 

 end of the bar usually is inclined slightly anteriorly. This vertical 

 black bar may be quite conspicuous, only partially formed, or absent. 

 It is seen most strikingly in populations of M. calif or nicum lutescens 

 which occur in the southern Great Plains (fig, 376), but it may be 

 found in many other populations in a somewhat modified or ob- 

 scured form (figs. 358-361, 363-365, 367, 370-372, 374-379, 383, 384, 

 and 387). 



In some populations additional black areas may blend with the 

 vertical black bar to form distinctive marks. One of these marks 

 commonly encountered in some areas is termed the "torso" mark 

 (figs. 9 and 7). It is formed by the addition of anterior and posterior 

 "arms" to the vertical black bar just below the black Dl setal group 

 which forms the "head" of the torso (fig. 9). The posterior arm usually 

 extends back to include setal group D2. A further modification of this 

 mark by the addition of one or more black areas on the lower posterior 

 edge is termed the "tailed torso" (fig. 9). Both the torso and tailed 

 torso marks are most common in populations oi M. calif ornicum pluviale 

 (figs. 370-372) and M. californicum recenseo (fig. 364), but all kinds of 

 intermediate marks between these and the vertical black bar can be 

 found in neighboring populations (see figs. 358, 360, 365, and 378). 

 In some larvae the black may be so extensive that the entire larva 

 appears black with practically no, or only very few, distinctive marks 

 (figs. 359, 361, 372, 377, and 384). 



Just anterior and just posterior to the vertical black bar approxi- 

 mately midway between the dorsal and ventral boundaries of the 

 subdorsal area are two spots termed the "anterior" and "posterior 

 subdorsal spots" (fig. 7). These spots are bluish-white and range 

 from being nearly absent (figs. 352-354) to being conspicuous spots 

 or blotches (figs. 356, 370, 384), or to being large areas that com- 

 pletely merge with the bluish subdorsal area so that no spot is apparent 

 (fig. 376, and others). 



The supraspiracular, subspiracular, and ventral areas do not have 

 any distinctive markings such as those just described for the more 

 dorsal areas. The color of these areas is usually a mixture of several 

 colors that blend together to give a color pattern (see fig. 371) that 

 may be characteristic for a given geographic region. 



The larva of M. californicum ambisimile (fig. 354) can be taken as an 

 example of how the basic pattern may be modified (or in this case 

 largely obscured). Typical c. ambisimile larvae are largely black, usually 

 lack a dorsal stripe, have small or no anterior and posterior subdorsal 



