8 Oklahoma Agricultural Experiment Station 



hatch readily in fourteen to fifteen days, by far the greater num- 

 ber requiring fifteen days. In hatching, the egg cap is pushed up 

 by the head of the emerging nymph, which gradually forces itself 

 out at the top of the shell by aid of the spines on its back. The 

 thin, delicate membranous sack about the nymph is forced up 

 with it and acts as a support for the small, compressed bug while 

 it is expanding and drying out and extending its legs and anten- 

 nae. This sack-like pellicle is split along the back after the nymph 

 is partially out of the shell and slips off over the head in front 

 carrying the egg cap with it. 



The time required from the time the nymph begins pushing up 

 the cap until it is free from the egg is approximately twenty min- 

 utes by actual count made on several occasions. The newly 

 hatched nymph begins feeding at once and grows rapidly ; at the 

 end of the third day it molts into the second stage. If the tem- 

 perature is very cool, the time may be extended a day, or even 

 more. 



The second stage is very much the same as the first, requiring 

 three days to get its growth, or a day or two longer if the weather 

 is cool. After molting to the third stage, another four clays are 

 necessary for the completion of this stage. I have observed a 

 very few to complete the third stage in three days, but by far the 

 greater number require at least four days under very favorable 

 conditions. The fourth and fifth stages each require at least five 

 days for full development with the temperature and moisture 

 ideal. 



Thus we see that the time required from the laying of the egg 

 to emergence of the adult, with optimum conditions, is: 



Egg 15 days 



First instar or stage 3 days 



Second instar 3 days 



Third instar 4 days 



Fourth instar 5 days 



Fifth instar 5 days 



Total 35 days 



This time may be reduced to thirty-three days in a few in- 

 stances when the egg stage lasts fourteen days and the third in- 

 star but three days. 



With cooler weather the time from the egg to adult may often 

 be extended to forty-six days, as was shown by several tests made 

 with the immature forms on a small tree placed near the "cold 

 room" from whence a chilly draft constantly passed over the bugs 

 which were on the lower leaves of the tree. 



In these experiments adults were isolated in pairs on leaves 

 by means of cloth cages tied about the twigs. The nymphs were 

 very difficult to enclose safely in anything of this type so were 



