ECOLOGY — INTERPRETATION OF ENVIRONMENT 411 



spring, and while green males are, very rare at this season, 

 green females are common; later the green form predominates 

 and the brown form is the one of exceptional occurrence, but 

 the males are less common than the females." These insects 

 are found throughout the summer in suitable localities. 



View of a landscape in the dune region in April, shoiving the 

 habitat of the granulated grouse locust {Tetrix granulata). 



The Grouse Locusts 



The grouse locusts are the smallest Acridians, and they will 

 be easily recognized from the photographic illustrations. They 

 are often found in marshy swales in early spring, such as 

 I have depicted in the typical landscape illustration on this 

 page. This particular view was taken at Dune Park, Indi- 

 ana, in April, and at the time I visited the spot the area 

 shown in the foreground was frecjuented by hundreds of granu- 

 lated grouse locusts, Tetrix granulata. These insects were sun- 

 ning themselves on the ground among the fragments of dead, 

 bleached bunchgrass and sedges. This part of the ground, 

 which was now dried out, had evidently been under water 

 but a short time previously. The row of granulated grouse 

 locusts presented in our second illustration shows seven 



