ONTOGENY OF IvARVAI, COI.OR PATTERNS. 147 



ings develop around the centers of color described as anterior and posterior 

 bands, Avhich later fuse, first in the middle portion of the body and still later 

 toward the ends, but which are always distinguishable laterally. These 

 markings are confined to the abdominal segments. The general body color 

 also changes in this stage fromi the pale, transparent lemon yellow of unde- 

 cimlineata to a chalky or ocher yellow. The color of the head, and some- 

 times that of the pronotum, shows a change to brown, as do also the legs. 



Closely allied to the two preceding species is signaticollis, whose larval col- 

 oration has ontogenetic stages very much like those of diversa. The first 

 stage in signaticollis (pi. 17, fig. i) is the same as the corresponding ones 

 in diversa and undecimlineata; the spines and viscous secretions enable the 

 trichomes of its food plant to become entangled and cemented to the body in 

 signaticollis in the same manner as in the two species just described, so that 

 in life on their native food plants the three species are indistinguishable. So, 

 too, the second stage of signaticollis is like the second stage of the other two 

 species, in that all excepting the spiracular, wing, and basal-pleural thoracic 

 spots are lost ; and there is the same habit of decorating the body surface with 

 the trichomes of its food plant. In the third and last stage, however, occurs 

 a striking change in coloration and habits. The color centers now redevelop 

 color on all the abdominal segments excepting the first three or four baso- 

 pleural spots and the anterior and posterior tergal areas (pi. 17, fig. 9). The 

 tergal bands arise on the three pairs of tergal centers and fuse first distalward, 

 and then, beginning mediad, fuse caudad to some extent ; but a large part of 

 both tergal bands remain free, as in the figure given. Sometimes the two do 

 not fuse or coalesce at all, but are clearly distinct. The general body color 

 likewise changes from a pale, transparent yellow to an opaque ocher or chrome 

 yellow. This change is due first to the appearance of lipochrome pigments in 

 the hypodermis, and, second, to the development of the opaque yellow fat 

 body. There is a striking parallel in the ontogeny of the coloration of diversa 

 and signaticollis. 



In L. midtitceniata and its allies the color development is also suggestive. 

 The first larval stage (pi. 17, fig. 10) has a color pattern exactly Hke those 

 of undecimlineata, diversa, and signaticollis, the four species being in their 

 coloration so nearly alike in the first larval stage as to be indistinguishable. 

 L. multitceniata, however, does not have the habit of covering its body with 

 trichomes, and it soon develops a deposit of bright yellow lipochrome hypo- 

 dermal pigments, which give it a bright yellow color of about the same shade 

 as the large, hard yellow spines of its food plant, Solamim rostratum. In the 

 second stage of development a change of coloration occurs, but one not as 

 pronounced as those in the three species just described. In multitceniata all 

 the spiracular, wing, and basal-pleural spots are retained in this stage, as are 

 also the inner and middle pairs of tergal centers on the last two thoracic and 

 the first three or four abdominal segments (pi. 17, fig. 11). The body color 



