Cockroaches, Locusts, Grasshoppers, and Crickets 147 



clear and transparent; the prothorax looked at from above appears to be 

 "pinched" at its middle. The males make a loud crackling when in the 

 air. 



It is familiar knowledge that locusts which are readily seen in the air 

 are extremely difficult to distinguish when alighted. This concealment, 

 resulting from a harmonizing of the body color with that of the grass or 

 soil, is of course an advantage to the locust in its "struggle for existence" 

 and is technically known as protective resemblance (see Chapter XVII). No 

 locusts show this protective resemblance better 

 than the species of Trimerotropis (Fig. 193) 

 especially familiar in the western states. The 

 colors of various individuals of a single species 

 vary with the soil colors of the locality, ranging 

 from whitish to 

 brownish to slaty 

 and bluish. I have 

 taken series of spe- 

 cimens of Trimero- 

 tropis sp. in Colorado 

 showing this whole 



range of 

 coloration. 



ground 



FIG. 192. FIG. 193. 



FIG. 192. Mestobregma cincta, male. (After Lugger; natural size indicated by line.) 

 FIG. 193. The maritime locust, Trimerotropis maritima, female. (After Lugger; nat- 

 ural size indicated by line.) 



The subfamily Tettiginae includes the strange little Acridiids known as 

 "grouse-locusts." They are all under inch in length, and most of 

 them are less than ^ inch. They have the wing-covers reduced to mere 

 scales, but the pronotum is so long that it extends back over the rest of the 



