10 
BULLETIN 256, U, S. DEPARTMENT OF AGRICULTURE. 
®dges meeting near their tips. With feeding and growth of the nymph 
Hie abdomen elongates without a corresponding growth of the wings, 
with the result that the latter reach only about to the sixth abdominal 
segment just before transformation to the adult. The pro thorax 
extends slightly over the dorsum of the metathorax. The white 
lings on the antennae, which have grown gradually fainter with each 
succeeding molt, are now but faintly visible. The external genitalia, 
the ovipositor in the female and the forked, supraanal spine in the 
male, appear to be almost as fully developed as in the adult. The 
njmph is about five-eighths inch long just after the molt to this ins tar. 
vase" 
Fxg. 10.— The fork-tailed katydid: Sixth-instar nymph. About three times natural size. (Original.) 
DURATION OF INSTARS. 
The duration of instars, averaged from all our records, was as 
follows: Instar I ranged from 10 to 35 days, with an average of 18.8 
days; instar II ranged from 8 to 13 days, with an average of 9.7 days; 
instar III ranged from 4 to 12 days, with an average of 7.1 days; 
instar IV ranged from 6 to 10 days, with an average of 8.3 days; 
instar V ranged from 3 to 15 days, with an average of 10.4 days; 
instar VI ranged from 12 to 20 days, with an average of 14 days. 
The complete nymphal stage required from 58 to 88 days. Nymphs 
issuing early in the spring were slower to become adults than those 
issuing later when the average temperatures were higher. 
MOLTING. 
After feeding for from 1 to 3 weeks the nymph ceases to eat and 
s^mains sluggish for from 24 to 48 hours. The skin then splits along 
