16 DEPAKTMENT BULLETIN 779. 



DURATION OF LIFE WITHOUT FOOD. 



The life of the adult is very short when deprived of food during its 

 period of normal activity in summer temperatures. Five pairs of 

 adults confined without food under a daily maximum temperature of 

 75° to 85° F. began dying on the second day and all were dead at the 

 end of the fifth day. Under the same circumstances five pairs of 

 adults kept under a daily maximum temperature 15° lower began 

 dying on the fifth day and all were dead at the end of the ninth day. 

 During hibernation the body of the adult contains much fatty tissue 

 which apparently acts as a reserve food supply. 



SEASONAL DEVELOPMENT. 



SEASONAL HISTORY. 



In the latitude of northeastern New Mexico the adults of Chloro- 

 chroa sayi emerge from hibernation during the first warm days of 

 late April or early May. At this time the ovaries of the females con- 

 tain fully developed eggs, and if mild weather conditions prevail 

 these eggs are deposited within a few days on the underside of the 

 rubbish or other material composing the hibernating quarters. 



The resulting nymphs feed and develop upon the young sprouts 

 of Russian thistle or other plants which have developed early in the 

 season under the protection of the accumulated rubbish. Upon reach- 

 ing maturity, about the last week in June, the adults of this first gen- 

 eration and the survivors of the overwintering brood migTate to the 

 fields of grain and feed upon the tender stems and developing heads 

 until the grain ripens. It is during this period that most of the 

 economic loss from the grain bug occurs. The females of this gen- 

 eration usually deposit their eggs on the underside of rubbish in the 

 field, or on Eussian thistle growing along the ditches, fence rows, or 

 waste areas. Occasionally eggs are deposited on different parts of 

 the host plant, notably the awns or beards of the head, but as a rule 

 the female seems to prefer the underside of some object near the 

 ground. The newly hatched nymphs from these eggs have not been 

 observed to feed upon the cultivated crops, but apparently depend 

 upon weeds, especially Russian thistle, for their sustenance until 

 reaching the third or fourth instar. 



The second generation is completed about the same time that the 

 majority of the grain crops are harvested, during the first week in 

 August. The surviving adults and large nymphs of the first two 

 generations then migrate to fields of late grain, milo maize, Sudan 

 grass, volunteer grain, or other food plants which then are developing 

 heads. If- none of these crops is present, the insects confine their 

 feeding to any of the native food plants growing in the vicinity. 



