166 UNITED STATES NATIONAL MUSEUM BULLETIN 276 



vertical black bar as in figure 367. Subdorsal line usually not present, 

 but sometimes visible as a small yellowish area on each segment. Both 

 subdorsal and supraspiracular areas blue, speckled with small black 

 spots surrounding bases of secondary setae. Subspiracular area gray- 

 blue-white, speckled with black spots at setal bases. Ventral area 

 mottled gray-white and black, with a black median spot on each seg- 

 ment. Primary dorsal setae varying from orange to blackish; secondary 

 dorsal setae orange. Primary lateral setae black or white; secondary 

 lateral setae white. Secondary setae moderate in length and density, 

 and not noticeably tufted. 



LARVAL DIAGNOSIS. — Typical specimens have white lateral 

 setae, orange dorsal setae, a broken blue-white middorsal stripe bor- 

 dered by black, and bluish lateral areas which usually do not have a 

 vertical black bar. All of these characteristics intergrade with those of 

 neighboring populations of M. calif or nicum. M. incur vum discoloratum is 

 the only species likely to be confused with c. fragile. Not all larvae of 

 c. fragile can be separated from those of i. discoloratum (figs. 395-399) 

 where they occur together, but in general, those of c. fragile usually 

 have a conspicuous middorsal, broken, blue-white line bordered with 

 addorsal black which contains a few inconspicuous orange markings. 

 Larvae of i. discoloratum generally have some dorsal black which may 

 be reduced to a black spot around setal group Dl, but they usually 

 have more conspicuous orange markings, and a less prominent bluish 

 to blue-white middorsal stripe which is often about the same color as 

 the subdorsal area. Also, in southwestern Utah setae SDl and SD2 are 

 black on c. fragile and white on i. discoloratum. This character should 

 separate the larvae found there, but it cannot be relied on as a general 

 character since setal color may vary within or between populations 

 found in other areas. 



EGG MASSES. — The eggs are laid as a basically flat, clasping 

 mass on twigs or branches. The spumaline is usually gray or gray- 

 brown and contains numerous minute dark specks (fig. 1 1 8) scattered 

 throughout it. See the section on egg masses for a discussion of these 

 specks (page 20). Southern Mojave Desert populations of c. fragile 

 probably have the highest density of specks and the least variation in 

 density between different egg masses from the same population. More 

 northern populations which are intergrading with the adjoining central 

 populations of M. calif ornicum may have variable densities of specks or 

 none at all in egg masses from the same local population. 



TENTS (fig. 335). — They construct large tents like those of other 

 populations of M. californicum. 



