ONTOGENY OF ADULT COLOR PATTERNS. 1 57 



after the wing has become uniform in color, development is slower, many 

 hours being consumed in its completion. After the attainment of the condi- 

 tion represented in fig. 27 the wing turns darker (fig. 28), and then becomes 

 nearly black (fig. 29). In fig. 28 a faint greenish color, which is due to phys- 

 ical causes, can be distinguished overlying the developing cuticula color. This 

 physical color increases as the cuticula color deepens and becomes a more 

 effectual absorptive layer, until from the faint greenish-blue tinge first 

 observed a blue-black, and finally a violet-black, has developed, as is shown 

 in figs. 29 and 30. 



ON THE HIND WINGS. 



Upon the secondaries or hind wings of Coleoptera the color pattern is always 

 simple. In Lcptinotarsa it consists of patterns in which the uniformly colored 

 surface is broken by areas of bright color, usually red. On plate 20, figs. 

 21 to 32, are given figures showing the ontogeny of the color in the hind 

 wings of signaticollis, oblongata, and dilecta. In signaticollis, soon after the 

 beetle leaves the pupa, the wing has the same opaque yellow-white color as 

 the elytron (fig. 21), and this is retained for some time. The adult color con- 

 sists of faint yellow-drab at the base of the wing (fig. 22) and between the 

 tracheae, which spreads rapidly distalward (fig. 23). In later stages this 

 becomes darker, and finally covers the tracheae and the entire wings. The com- 

 pleted adult coloration is represented in fig. 24. In oblongata (figs. 25 to 28) 

 and dilecta (figs. 29 to 32) are found similar stages, excepting that in these, 

 as in oblongata, a red color develops after the yellow-drab and moves distal- 

 ward from the basal portion of the wing to about its middle. 



Fundamental likenesses are clearly distinguishable in the ontogeny of the 

 color pattern of the wings of these beetles, even although they are specialized. 

 Thus both possess initial stages which are identical as far as color is con- 

 cerned, and both have a brief period during which the color pattern is marked 

 out and a longer one during which it is developed. Further, in the develop- 

 ment of both elytra and hind wings, color appears first proximally in the 

 costal, subcostal, and ramous interspaces, and spreads distalward and caudal- 

 ward. 



The Ontogeny of Color on the Abdominal and Thoracic Segments. 



The development of the color pattern on the abdominal segments follows in 

 Leptinotarsa the same laws which have been found to hold for Coleoptera in 

 general. That is, the color pattern begins in a series of metamerically placed 

 centers, and from these spreads out. This color development is represented 

 on plate 20 as found on the ventral surface of the segments of undecimlinc- 

 ata (figs. 6 to 10) and of oblongata (figs. 1 to 5). In the figures given both 

 have a similar initial stage in which the general pattern on the segments is a 



