174 



COI.ORATION IN LEPTINOTARSA. 

 Table 54. — Temperature conditions. 



Conditions— 



7 a. m. 



I p. m. 



8 p. m. 



Maxi- 

 mum. 



Mini- 

 mum. 



Aver- 

 age. 



Deviation 



from 



normal. 



In nature 



In experiment. . 



19.2 

 7 



30.62 

 12.009 



° C. 



17.389 

 8 



C. 

 33-5 

 15.5 



° C. 

 13 



6 



22.403 

 9.003 



° C. 

 



-13-4 



In these experiments 88 per cent died in the larval and prepupal stages, 

 7 per cent in the pupal, and 5 per cent appeared as imagines, of which there 

 were 70 females and 80 males. The pupal period averaged 43 days, or over 

 four times that in nature. The hypodermal color was a light yellowish-white, 

 and many of the spots of the cuticula were absent or small. On the epi- 

 cranium g and g' were separate, small, and light brown in color, while h and 

 W were often absent. On the pronotum there were no fusions, and h, d, and f 

 were always very small and frequently absent. The elytral stripes were 

 shortened and were light in color, while upon the ventral surface the middle 

 sternals were largely wanting, and the legs were almost devoid of dark color. 

 The general appearance was decidedly albinic, as is shown by the following 

 seriations : 



Table 55. — General color of beetles used. 



Class 



4 



5 I 6 



1 



7 



8 



9 



10 



II 



12 



13 



14 





P.ct. 



P.ct. 



p.ct. 



Pet. 



P.ct. 



Pet. 



P.ct. 



Pet. 



P.ct. 



p.ct. 



P.ct. 



Parents 





I 



2 



5 



20 



42 



18 



9 



2 



I 





Control 



. . 



. . 



2 



7 



10 



23 



30 



16 



6 



5 



I 



Kxperiment. . 



2 



10 



24 



22 



20 



12 



8 



2 









Empirical mode of parents 9 



Empirical mode of control 10 



Empirical mode in experiment ... 6 



Modal deviation of parents o 



Modal deviation of control -\-i 



Modal deviation in experiment . . — 3 



Experiment 7. — To determine the effect of an extremely low temperature deviation 

 upon the color and color pattern of L. decemlineata. 



Conditions. — Temperature on the average 23.5° C. below that in nature. 

 Relative humidity increased in some experiments 7 to 10 per cent; light 

 decreased to one-half its normal intensity. 



Apparatus. — Glass tanks with jacket of ice and salt between. Use was 

 also made of an ice box. 



In this experiment, which was conducted during the years 1900 to 1904, 

 2,000 larvae were used. These were taken at random from potato patches in 

 the last instar and were placed in glass vessels. Food, moisture, and soil were 

 the same as in nature, but the light was greatly diminished or entirely want- 



