144 



COLORATION IN LEPTINOTARSA. 



larvae of many Leptinotarsas (iindecimlineata, decemlineata, signaticollis, etc.) 

 we find color areas or centers which are represented diagrammatically in text- 

 figure 7 as seen from the side, and in text-figure 8 as seen from above. An 

 abdominal segment (text-fig. 9), which represents the simplest condition, 

 shows the skeletal ring composed of paired tergse, pleurae, and sternae. Upon 

 each of these are color centers which are placed in a constant morphological 

 position and have definite relations to the structure of the animal. Upon the 

 tergum are found on either side of the median line three pairs of color centers 

 divided by a crease or furrow into two series. These are designated the outer, 

 middle, and inner tergal centers, and they exist as an anterior and posterior 

 series (text-figs. 7 and 8). Each of these centers may consist of one, two. 



anterior median pronotal spot 



posterior median s 



pronotal spot *^^ 



inner-tergals 



anterior lateral epicranial 



^ ^ „^po8terior lateral epicranial 



janterior pronotal band 



.posterior pronotal band 



. _ . .~ —— —outer tergal 



• middle tergal 



wing spots 

 • rf" spiracula 



baso-pleural 



spiracula. 



anterior tergal band 



•^—posterior tergal band 



Text -FIGURE 8.— Diagrammatic representation of the color centers shown in text-figure 7 

 when seen from the dorsal side. 



or three small, closely placed spots, and in many species they are the locations 

 of spines. This type of coloration is found not only upon all the tergae of the 

 abdominal segments, but also upon the last two thoracic tergae. Upon the 

 anterior thoracic tergum or pronotum, however, there appear in the larvae 

 the anterior and posterior pronotal bands (text-figs. 7 and 9), which are homo- 

 dynamous with the anterior and posterior tergal system of centers of the pos- 

 terior segments. This same type, further obscured, is seen in the epicranium, 

 where there exist the anterior and posterior lateral epicranial areas, each 

 homodynamous with the abdominal tergal areas. The anterior and posterior 

 median spots (text-fig. 8), which often appear upon the pronotum, are the 

 only ones not found in this series of abdominal tergal centers. On the side 



