170 



COLORATION IN LEPTINOTARSA. 



In these experiments 55 per cent died in the larval stage, 45 per cent in the 

 pupal, and 5 per cent completed their transformation. These were normal in 

 shape, but 23 per cent below the average in size. The color and color pat- 

 terns were changed as follows : The hypodermal color became pale yellowish- 

 white, and the areas of cuticula pigments were considerably altered. All of 

 the elytral stripes were shortened and narrowed, and showed no fusions ; the 

 spots on the pronotum and epicranium were also without fusions and small, 

 / and f being continually absent, and d and b being represented only by traces 

 of color. On the ventral surface nearly all the color was lost, traces only of 

 the outer sternals remaining, and rarely of the inner sternals. The general 

 appearance of the imagines and their seriations as regards general color are 

 shown in the following table : 



Table 47. General color of beetles used. 



Empirical mode of parents 9 



Empirical mode of control 10 



Empirical mode in experiment . . 4 



Modal deviation of parents o 



Modal deviation of control .... +1 

 Modal deviation in experiment. . 5 



In each of the separate experiments comprising this second set the resulting 

 individuals showed a strong prophetic skewness toward an albinic condition. 

 This was due to the general reduction in size of all areas of cuticula pigment, 

 to the loss of many, and to the change in the hypodermal color already noted. 



Experiment 3. To determine the effect of a high average deviation of temperature 

 upon the color and color pattern of L. decemlincata. 



Conditions. Temperature on the average 12.097 C. above that in nature. 

 Other conditions normal. 



Apparatus. The same as in experiment 1, artificial heat, however, being 

 used to some extent. 



Ten thousand one hundred larvas of L. decemlincata, taken at random from 

 potato fields, were subjected to the conditions of this experiment, which 

 extended over the years 1894 to 1904. All the larvae were placed at the 

 beginning of the last instar, a temperature condition similar to that found in 

 nature, and the temperature was raised in four or five days to the desired 

 degree. Food, moisture, light, soil, etc., were kept normal. The tempera- 

 ture records are given in the following table : 



