December, '10] SEVERINS: dryness and walking-sticks 479 



the fifth. Only four stages of growth between the egg and the mature 

 form have hitherto been recognized. Dr. L. O. Howard stated in 

 1901,'^ "The natural egg piace of this common insect is not known, 

 but the rest of its life has been well worked out by Woodworth, al- 

 though there is probably one more molt than he has observed, i. e., 

 five instead of four." The senior writer has also said of this species, 

 "There is little doubt that there are five stages, to agree with other 

 species of plant-bugs which have been traced through their meta- 

 morphoses," this deduction having been drawn from his experience 

 in rearing Anasa and Leptoglossus and that of Quaintance and 

 Slingerland, who have observed five nymphal stages of Pamera vinda 

 Say and Poecilocapsus lineatus Fab., respectively. 



THE EFFECT OF MOISTURE AND DRYNESS ON THE 

 EMERGENCE FROM THE EGG OF THE WALKING- 

 STICK, DIAPHEROMERA FEMORATA SAY 



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 



Heymons^, Godelmann^ and Stokard^ have all noticed that in 

 various species of Phasmidae some specimens, after issuing from the 

 egg, may have one or more legs caught within the egg-shell and drag 

 it after them for hours. Besides confirming these observations we 

 frequently noticed that one or both antennae or even the abdomen 

 together with one or more legs may fail to be withdrawn from the 

 egg-capsule. Some specimens, after having withdrawn the pro- 

 thorax, part of the head and mesothorax, were unable to extricate 

 themselves further. 



A number of experiments were performed in order to determine why 

 the walking-sticks fail to emerge completely from the egg-shell. One 

 thousand eggs were kept on wet sand in a breeding cage; another 

 thousand were put in a tin box and kept perfectly dry from the time 

 they were deposited in the autumn. The follo\ving table shows the 

 results of hatchings of two hundred eggs kept in dry and moist 

 surroundings. 



The table shows that 13% of the 200 specimens hatched under wet 

 conditions, and 94% of the 200 specimens hatched under dry con- 



»The Insect Book, New York, 1901, p. 301. 



