June, '11] SEVERINS ON WALKING-STICK 307 



THE LIFE-HISTORY OF THE WALKING-STICK, DIAPHE- 

 ROMERA FEMORATA SAY 



By Henry H. P. Severin, Ph. D., Professor of Zoology and Entomology, College of 

 Hawaii, and Harry C. Severin, M. A., Professor of Entomology, South Dakota 

 State College of Agriculture and Mechanic Arts 



(With Figs. 7-9, in Text.) 



A number of naturalists have worked on the life-history of Dia- 

 pheromera femorata, without as yet having accurately determined 

 the number of molts that this insect undergoes. Riley (63, 73, 74 

 and 76) claims in several papers that this species "molts but twice," 

 and this mistake has been carried into a number of text-books on 

 entomology as well as into some bulletins and reports of the State 

 Experiment Stations. Thomson (97) had some eggs of Diapheroniera 

 femorata sent to him from Toronto, Canada, and reared the walking- 

 sticks which hatched from these in the Zoological Society's Garden 

 at London. He claims that his specimens molted but four times. 

 During the last four years we reared one hundred Diapheromera 

 femorata under conditions which we made as normal as possible and 

 found that twenty-three per cent, molted four times, seventy-six 

 per cent, five times, and only one per cent, six times. 



Bordage (8), in working with the walking-sticks, Monandroptera 

 inuncaris and Raphiderus scabrosus, found that there were five or 

 six molts in both of these species. De Sinety (90) found that the 

 Asiatic species, Menexenus ohtusespinosus, molted either four or five 

 times and Dixippus morosus five or six times. Meissner (55), how- 

 ever, in a recent paper on Dixippus rnorosus claims that "samtliche 

 42 von mir bis zum Imaginalstadium gezogenen Tiere haben sechs 

 Hautungen durchgemacht; ich halte es auch fiir unwahrscheinlich, 

 dass weniger vorkommen sollten." Evidently, this author was not 

 acquainted with de Sinety's (90) work on this same species. La 

 Baume (4), in a recent paper on Dixippus morosus, writes as follows 

 concerning the number of molts of this insect: ''Die Anzahl der 

 Hautungen gibt de Sinety auf 4 bis 6 an . . ." Evidently La 

 Baume has erred, for de Sinety writes, ''Dans les especes asiatiques, 

 nous en avons constate tantot un nombre fixe, . . . peut-etre 

 faute d'un nombre suffisant d'experiences 7 chez Clitumnus patellifer 

 tantot un nombre variable; 5 et 4 {Menexenus ohtusespinosus) , 6 et 5 

 {Dixippus morosus)." 



The question naturally arises, what is the probable explanation of 

 this discrepancy concerning the number of molts of Diapheromera 

 femorata? Diapheromera, after casting its exoskeleton, eats a large 



