$7% PHYSICAL GEOGRAPHY. 



ern Illinois, the only southern locality I know ; at least, Mr. Thomas sent 

 it to me from there : could he have received it from some other quarter ? 

 This insect, like the preceding, stridulates at will during flight ; the flight 

 is well sustained, and the insect is capable of changing its course. At 

 each turn it accompanies the movement with a swoop-like curve, and 



Fig. 59. 



kla kla kla kla kla kla kla 



- 9 '- 0- 0t Hi. 



I I L 



v V / 



-S I ^ * O '- ^ i mv I- 



X 



kla kla kla kla kla kla 



#i 0-X0 H 0t 0- # i _ 



i vn C t ^ r 



Note of Triinerotropis verruculata. 



emits a crackling sound. In verruculata the sound is like kl or kla, the 

 former at a distance, the latter nearer by; it is repeated at the rate of 

 about five per second. Just before alighting, it crackles more rapidly 

 and frequently. 



36. Triinerotropis maritima Stal. This curious grasshopper is a good 

 example of mimicry, for it so closely resembles the color of the sand on 

 a sea-beach that it is difficult to see it when alighted. It is found only 

 in such localities, and reaches its northern limits about the narrow part 

 of the state washed by the sea. I have taken it at Hampton. South- 

 ward it extends at least as far as New Jersey. 



37. Camnula pcllucida (CEdipoda pelhicida Scudd.) This insect is 

 silent in flight, and is a northern species, swarming in immense numbers 

 among the White Mountains and on the dry summits of the country 

 south of it. The top of Mt. Prospect, near Plymouth, was covered with 

 myriads of them in the autumn of 1873. It is found, however, as far 

 south as Connecticut and southern Illinois, and west to the latter region 

 and Lake Superior. It is very closely allied to C. atrox of the Pacific 

 coast, which is said to be the most destructive grasshopper there, and to 

 migrate in swarms like Melanoplus spretus. 



38. Tettix gramilata Scudd. This is a northern insect, occurring 

 throughout the state, even into the valleys of the White Mountains. 

 Southward it extends as far as the middle states, but is most common 

 farther north ; it occurs at Hudson's bay and about Lake Huron, and as 

 far west as Minnesota. Kirby took it in Arctic America, as far north 

 as lat. 65 , probably near Fort Simpson. 



