THE GEAIIT BUG. 17 



The individuals of the third generation,, progeny of these adults, 

 feed on the late grain crops, or on their native food plants, and reach 

 maturity about the middle of September. 



A very large percentage of the third-generation females do not 



oviposit until the following spring, but during favorable seasons a 



few of the earliest maturing individuals of this generation sometimes 



. deposit eggs from which adults of a partial fourth generation develop, 



although most of the nymplis do not reach maturity. 



With the advent of cold weather, in October or November, the 

 surviving adults of the later generations seek hibernating quarters 

 for the winter. Many nymphs in all stages of development also 

 enter hibernation at this time but do not survive the winter. 



SL'MMAEY OF SEASONAL HISTORY. 



Hibernating adults deposit eggs during late April or early May. 



First-generation nymphs feed on native plants and develop to ma- 

 turity in late June. Adults migrate to grain fields and feed on de- 

 veloping heads. 



Second-generation nymphs feed on native plants or grain heads and 

 develop to maturity in late August. Adults migrate to fields of late 

 grain or feed on native plants. 



Third-generation nymphs feed as in the preceding generation and 

 develop to maturity by the middle of September. Adults feed 

 mostly on native plants. 



A partial fourth generation develops on native plants and ma- 

 tures just before the advent of cold weather. 



Adults of the second, third, and fourth generations enter hiberna- 

 tion during late October or early November. Nymphs enter hiberna- 

 tion but do not survive the winter. 



NUMBER OF GENERATIONS. 



In the section where these observations were made there are three 

 distinct generations each year and sometimes a partial fourth genera- 

 tion. The broods overlap considerably and all stages of the insect 

 may be found in the field from the middle of May until the species 

 enters its hibernation quarters in October or November. 



SEASONAL ABUNDANCE. 



The adults of the grain bug are very numerous locally during the 

 time of their emergence from hibernation in April and May. In 

 one instance 30 adults were found under a single " cow chip " about 

 6 inches square; and a total of 175 adults were found under the 

 dead weeds along a 20-foot space of an irrigation ditch. The period 

 of greatest abundance occurs, however, after the development of the 

 second generation in late June and during July. At this time many 

 103881°— 19 3 



