208 



SOME ASPECTS OF ECOLOGY 



Peairs (1927) is one of the more recent workers to investigate 

 the relation of temperature to insect development. His experi- 

 ments were made on a considerable scale with a number of 

 different species of insects (larvae, pupa;, and, in one experiment, 

 eggs), which were divided into batches, each batch being subjected 



50 iQo IS* 20" 25" 50" 550 



Fig. 67. Velocity of development of Lucilia ccesar larvae. A, based 

 upon mean time of emergence. B, based upon average time of 

 first emergence for the lots at different temperatures (C°). 

 (From Peairs, West Virginia Agric. Exp. Sta. Bull., 208, 1927.) 



to a different constant temperature. The relative humidity was 

 not constant, but was usually maintained near the point of 

 saturation. In presenting his data the reciprocals of the time 

 factor have been plotted against the temperatures, and the curves 

 consequently show the direct relation between increase in velocity 

 of development and rise in temperature (Fig. 67). The curves 

 in all cases approximate within certain limits to a straight line, 



