126 UNITED STATES NATIONAL MUSEUM BULLETIN 276 



than the length of the foretibia for americanum, but it almost always is 

 distinctly less for californicum. 



Female californicum with light lines on the forewings are most likely to 

 be confused with americanum, but americanum always can be identified 

 by the heavily sclerotized genital plate with the ostium near the an- 

 terior edge. Female californicum may have a heavily sclerotized genital 

 plate, but the ostium is never near the anterior edge. Female californi- 

 cum with dark lines may be confused with disstria, constrictum, or tigris, 

 but those species can be positively identified by the ovipositor charac- 

 ters given for them (pages 86, 94, 103, respectively). 



MATURE LARVAE (figs. 352-389).— Color pattern highly varia- 

 ble, especially in the Great Basin and Rocky Mountains. Middorsal 

 area with or without a stripe, but usually with a broken stripe formed 

 by a blue-white to bluish dash on each segment. Addorsal area black or 

 mixed orange and black. Subdorsal, supraspiracular, and subspiracular 

 areas varying combinations of orange, black, and blue. Many larvae 

 have a vertical black bar on each segment; some specimens have addi- 

 tional black markings on both anterior and posterior sides of the bar 

 which may merge with it to form the "torso" mark. Both primary and 

 secondary dorsal setae usually orange, but occasionally white, and 

 rarely the primary setae may be black. Primary lateral setae usually 

 orange or white, rarely black. Secondary lateral setae orange or white, 

 sometimes somewhat tufted. 



LARVAL DIAGNOSIS. — Larvae of disstria, americanum, constrictum, 

 and tigris can be separated from californicum by the characters given in 

 the larval diagnosis for each of them. Any larva which has a broken 

 middorsal stripe formed by a blue-white to bluish dash on each segment 

 is probably californicum, since the only other larvae which have similar 

 markings are some specimens of irwurviim. See the larval diagnosis for 

 :. incurvum (page 1 75) for the best way to separate incurvum from californi- 

 cum in Arizona, and the larval diagnosis for i. discoloratum (page 179) for 

 the best way to separate them in the southern Utah region. Larvae 

 without the broken middorsal stripe usually are completely unmarked 

 dorsally except that the black middorsal area may be outlined by orange 

 markings on both sides. Such specimens may occur in many areas, but 

 the yare most often found around San Francisco Bay in California and in 

 the "four-comers" area of the Southwest (37° N. Lat., 109° W. Long.). 



EGG MASSES (figs. 105, 112, 115, 116).— The egg mass is always 

 laid as a basically flat, clasping mass, the amount of curvature depend- 

 ing on the size of the twig or branch on which it is laid. They may be 

 laid on small twigs, larger branches, or even on small trunlcs of young 

 trees or shrubs. They are always covered with spumaline which varies 

 considerably, ranging in color from dark brown to pale gray or even 



