26 DEPARTMENT BULLETIN 179. 
quently results in the concentration of 6 or 8 individuals on one 
grain head while similar plants in the vicinity receive but slight 
attention from the species. When large numbers of the insects are 
present in fields of wide area the adults appear to concentrate in 
certain portions of the field and change their location as the food 
supply becomes exhausted. 
It is problematical whether this gregarious habit exhibited by the 
grain bug is a result of an attraction between the individuals or is 
largely stimulated by the presence of attractive food during its period 
of feeding and by superior facilities for protection during its inactive 
periods. 
FLIGHT. 
Generally the adults are very sluggish flyers and their flight is 
limited to a short distance. When disturbed they habitually drop to 
the ground for the purpose of seeking concealment without attempt- 
ing flight. Under special conditions, however, the adults are capable 
of long and sustained flight. On June 30, 1916, large numbers of the 
adults were present on a small plot of wheat growing in the insectary 
grounds at Maxwell. The day was very warm, with no wind, and 
at this time when disturbed the adults took to flight and gradually 
ascended to a height of from 10 to 30 feet in the air, from this altitude 
maintaining a straight course as far as the eye could follow. Similar 
observations have been made in the field from time to time, and it is 
probable that these migrations generally are traceable to the need of 
a fresh food supply. 
The adults have not been observed in flight during windy days, but 
the fact that they commonly migrate to the leeward side of the field 
at these times would indicate that their general line of flight was in 
the same direction as the prevailing wind. 
On October 2, 1916, during a windy period, large numbers of 
adults were found feeding on the Russian thistle growing in the 
northeast corner of an abandoned wheat field. The wind was from 
the southwest, and although the adults were found in small numbers 
throughout the field, most of them apparently had been driven to 
their present location by the prevailing wind. 
HIBERNATION. 
The grain bug hibernates exclusively in the adult stage. No im- 
mature forms have been observed to survive the winter, although 
many of the larger nymphs enter hibernation with the adults and 
live for a short time. 
LOCATION OF HIBERNATING QUARTERS. 
In general, Chlorochroa sayi hibernates under and among dead 
weeds or rubbish, in crevices under the loose bark of trees or posts, 
