ONTOGENY OF LARVAL COLOR PATTERNS. I49 



thorax, the first larval stage has a color pattern of a generalized character, 

 with all the color centers described in the beginning of this section clearly rep- 

 resented. The second stage, however, shows in all a marked change in color 

 pattern in the reduction of many centers. The centers first to go are the pos- 

 terior tergal and sternal, and the last are the thoracic baso-pleural, while the 

 spiracula and wing centers are never lost, although the posterior members 

 may be reduced. On the pronotum it is the anterior band that is reduced. 

 In the species oblongata, juncta, and defecta the first larval stage possesses a 

 color pattern like the second stage of the other species of this group ; and if 

 the color centers not found in the larvae appear at all it is only in the embryo 

 as very transient characters, or in the imago. Thus it appears that these cen- 

 ters are not lost when the stages are missing, but are only quiescent. 



In other groups of this genus the larvae likewise show stages or series of 

 stages which are of interest. These, however, do not present the generalized 

 conditions found in the lincata group, although the coloration of the larvae of 

 the entire genus starts with a condition comparable to the earlier stages in that 

 group. In haldemani and violescens the first larval stage shows the spirac- 

 ular, wing, baso-pleural, and sternal centers of coloration on the anterior four 

 or five abdominal segments. The general body color is red, due to red lipo- 

 chromes in the hypodermal cells (pi. 17, figs. 25 and 31). In the second 

 stage of both species all of the color centers are lost, excepting the spiracular 

 and wing and traces of the baso-pleural thoracic spots. The wing spots are 

 reduced to crescentic markings and the pronotal bands are much reduced, 

 as is shown in figs. 26 and 32, plate 17. On the head the reduction of color 

 is carried to the extent that all dark markings are lost, excepting the 

 retinal pigment and that at the tips of the mandibles. There is also a marked 

 change in the body color from opaque reddish to a nearly transparent pale 

 yellow-white. In the last stage the reduction of the dark color is somewhat 

 more marked, but the chief change is in the body color, which becomes pale 

 opaque yellow in violescens and corn yellow in haldemani (pi. 17, figs. 27 

 and 33). 



In L. dilecta is found a series of color-pattern stages which are in the main 

 comparable to those just described for haldemani and violescens. The larva 

 is at first red, with spiracular, wing, baso-pleural, and sternal centers of col- 

 oration represented, and with spines on the ventral surface (pi. 17, fig. 28). 

 In the second stage all excepting the spiracula and wing centers are lost, the 

 pronotal stripes are reduced, and color disappears from the head. The body is 

 a general transparent pale yellow-white. In the last stage the color becomes 

 grayish yellow, the anterior tergals unite to form bands, the wing spots 

 are mere crescentic lines, and the larva shows the condition rather unusual for 

 this genus, which is shown in fig. 30. In forms like rubiginosa larval devel- 

 opment starts with the centers much reduced, and finally reaches the condition 

 shown on plate 17, fig. 36. 



