THE GENETICS OF HABROBRACON JUGLANDIS ASHMEAD 



if any change, the intensity of the eye colors 

 varies inversely with the temperature, in con- 

 trast to that of body color (type and lemon) 

 which varies directly with the temperature. 

 Carrot showed wide variation from white at low 

 temperature to a deep reddish carrot at high 

 temperature, maroon showed less variation, from 

 a bright red to a dark red or black, and the com- 

 bination, carrot-maroon, showed still less vari- 

 ation from white to pale yellow. White-eyed 

 carrot wasps were phenotypically like geneti- 

 cally white-eyed. The bright red of the maroon 

 was similar to the deep reddish orange of the 

 carrot. Body color is determined earlier in de- 

 velopment than is eye color. 



Temperature treatment affects fecundity al- 

 though short time exposure to cold has only a 

 slight effect. Constant high temperature de- 

 creases fecundity by a little less than a third 

 and constant low temperature lowers it to less 

 than half that of control wasps. Constant cold 

 and extreme heat both have very significant ef- 

 fects on fecundity though they apparently act 

 in different v/ays. Cold acts by slowing down 

 all the activities of the adult wasps thereby 

 decreasing the rate of egg production. Cold al- 

 so keeps many of the eggs from hatching and 

 kills many of the young larval wasps. Heat 

 treatment apparently has little or no effect on 

 rate of egg production. It affects the young, 

 the consequences being especially noted in the 

 pupal stage. There are many naked pupae and 

 many dead in the cocoons. 



Maercks (1933) investigated the influence of 

 temperature and relative humidity on the eggs 

 of Habrobracon. He found the optimal tempera- 



126 



