400 NATURE SKETCHES IN TEMPERATE AMERICA 



similar instances among the Acridians, I have observed a notable 

 advantage to the species possessing two or more color phases 

 coexisting in individuals of the same species. In this case 

 it is obvious that its vertebrate enemies such as birds, snakes, 

 toads, and perhaps gophers are much less apt to discover them, 

 because the deception practised is probably more efficient 

 than in monochromatic, or one-colored insects, under the same 

 conditions, especially when these colors are in harmony with 

 the surroundings. 



It is a noteworthy fact that the grasses among which these 

 Orthoptera live are subject to frequent fluctations in color, 

 from green to ochreous brown, depending on humid conditions 

 or drought. Both color patterns are always present in different 

 individuals during their life period in summer. 



The legends under the illustrations describe the color phases 

 of this species, so that with these descriptions, it is hoped the 

 reader will have little difficulty in familiarizing himself with 

 these insects. In the chapter on "Meadow Echoes" I have 

 considered the subject of the relation of plants to the physical 

 conditions of the soil; the pasture differing from the meadow 

 in being drier, and its prevailing plants consisting of grasses. 

 In the sketch given above, the pasture locust is a well-marked 

 example of the adaptation of an insect to the plant societies 

 of the pasture. 



The Short-horned Locust 



To understand insect life, one must study a species in its 

 natural environment. Here one learns certain facts pertaining 

 to their behavior, and elicits from nature the important cir- 

 cumstances bearing on their life relations. I have shown in 

 another chapter how thoroughly adapted some of the Orthop- 

 tera have become to their habitat. Some of these insects are 

 so well adapted to a special kind of plant group that they 

 fail to exist elsewhere. I refer here to the short-horned locust, 

 known as Tryxalis brevicornis. As will be seen, its interrelation 

 to its surroundings is of a very exacting kind. In the plate 

 photographic illustration, I have depicted this handsome species 

 by four figures. This insect presents a graceful form, having 

 a produced conical head. From an economical standpoint 



