414 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 7 



metabolism is not only variable at different temperatures, but variable 

 for different developmental stages at the same temperature and, what 

 is still more striking, variable for the same developmental stages under 

 the same temperature at different times in the year. He points out 

 that consequently the curve, illustrating the temperature relationship 

 of each developmental stage for each period of the year when it occurs, 

 must be determined before the measurement of the temperature effect 

 can be made exact. 



The work thus far has served to emphasize the absolute necessity 

 for the systematic accumulation of data relative to the temperature 

 effect, and it is for the purpose of presenting some of this type 

 of matter that the temperature portion of this paper has been 

 written. 



The material used in this study was the apterus female of the south- 

 ern grain louse {Toxoptera graminum Rodani), its chief parasitic enemy 

 {Lysiphlehus tritici Ashm.) and the chinch bug {Blissus leucopterus Say) 

 with and without chinch-bug fungous {Sporotrichum globuliferum Speg.) 

 infection. 



The materials for the study of the southern grain louse and its para- 

 site were taken at the beginning of each experiment from outdoor 

 conditions when the season of the year permitted, and at other times 

 from greenhouse rearings. The chinch bug material was taken directly 

 from the field at the beginning of each experiment. 



In all cases, except two, the tests were made in constant temperature 

 and moisture incubators of the type described to the Entomological 

 Society of America at Boston in 1910. The two exceptions were 

 breedings made in the greenhouse for the purpose of finding what dif- 

 ference, if any, could be attributed to breeding under the incubator 

 conditions. The organisms under experiment were in all cases sup- 

 plied with an abundance of attractive food, consisting of young wheat 

 plants. Each test with the southern grain louse involved carrying 

 from six to forty-one individuals throughout their life cycles. Each 

 test with its parasite involved, taking the average of the response of 

 from two to ten pairs and their progeny. Each test with the chinch 

 bug involved the response of about twenty individuals. 



In summarizing the meaning of these temperature data it may be 

 said that the response of insect protoplasm, as exhibited in variations 

 of the rate of metabolism, appears to depend upon: (1) where in the 

 particular insect's temperature range the temperature changes occur; 

 (2) the type of metabolism characteristic of the insect, when the 

 response is taken; (3) the presence of any abnormal factor such as. 

 parasitism. 



