Explanation of Plate 19. 



This plate illustrates the development of the color pattern upon the elytra 

 of several species of Leptinotarsa. 



Figs. 1 to 6, L. undecimlineata. 



Figs. 7 to 12, L. dilecta. 



Figs. 13 to 18, L. zetterstedli. 



Figs. 19 to 24, L. rubiginosa. 



Figs. 25 to 30, L. violescens. 



