14 



ENTOMOLOGICAL NEWS. 



[Jan., '13 



The Effect of Temperature on the Molting of the 



Walking-stick, Diapheromera femorata Say 



(Orthop,). 



By Henry H. P. Severin, Ph.D., Honorary Fellow, University 



of Wisconsin, and Harry C. Severin, M.A., Professor 



of Entomology, South Dakota State College of 



Agriculture and Mechanic Arts. 



In a recent paper we ( i ) called attention to the fact that of 

 one hundred Diapheromera femorata reared under as nearly 

 normal or field conditions as possible during June, July and 

 August, the months during which the development of this 

 Phasmid occurs in its natural habitat in Wisconsin, 23 per 

 cent, molted four times, 76 per cent, five times, and only i 

 per cent, six times. The suggestion was also made that "in 

 all probability temperature plays an important role in the rate 

 of development." To determine with certainty what effect tem- 

 perature has on the molting of this walking-stick, a number 

 of experiments were performed. 



In order to compare the data obtained by rearing some of 

 these insects under normal conditions with specimens bred 

 under a temperature either higher or lower than field condi- 

 tions, the following table containing the averages of the inter- 

 vals or periods between molts (stages or stadia) and the total 

 duration of the periods (post-embryonic development) of five 



TABLE I. 



AVERAGES IN DAYS OF THE STAGES BETWEEN MOLTS OF DIAPHERO- 

 MERA FEMORATA REARED UNDER NEARLY FIELD CONDITIONS IN 

 JUNE. JULY AND AUGUST. 



