14 NORTH AMERICAN ACRIDIID^E. 



LOCUST SOCIETIES AND HABITATS. 



Independently of their zonal distribution, the Acridiidae may 

 be arranged, according to their habits, in local groups which we 

 call, for lack of a better name, societies or associations of species. 

 These groups will vary more or less according to the importance 

 attached to various environmental factors by the person arranging 

 them. We may follow the botanists and recognize hygrophile, 

 xerophile, and other groups, based upon distribution with reference 

 to soil humidity. We may divide them into campestral and sylvan 

 series, frequenting respectively open fields and savannas or forestal 

 environments. Or we may arrange them in still other ways. 



We find, it is true, species which are characteristic of these 

 various surroundings, and others whose habitats are not so readily 

 classified, or which, widely distributed zonally and geographically, 

 show no especial predilection for any definite kind of environment. 

 A complete and satisfactory classification of locust societies has yet 

 to be made. The hurried character of the trip forbade critical 

 study of this topic, and mention here is made of but a few of the more 

 noticeable features connected with the subject in the territory under 

 consideration. 



The following table shows the classification in outline of the 

 societies which I have found easily recognizable in the Eastern 

 States, but it needs to be amplified by further study. Fuller 

 details of distribution will be found in the list of species (p. 24). 



Locust societies of eastern North America. 



Geophilous division. Phytophilous division. 



Campestrian group. Campestrian group. 



Xerophile societies : Xerophile societies : 



Saxicolous species. Hygrophile " 



Arenicolous " Sylvan group. 



Humicolous " Thamnophile societies. 



Hygrophile societies : Dendrophile " 

 Humicolous species. 

 Paludicolous " 

 Limicolous ' ' 

 Sylvan group. 



Geophilous locusts are those which freely come into direct 

 contact with the soil and whose local distribution is largely con- 

 trolled by its character. Phytophilous locusts, on the other hand, 

 have much closer relations with the vegetal covering of the soil, be 

 it grass or tree. This primary difference in habits is accompanied 

 by a structural difference in the relative development of the tarsal 

 pulvilli large in the plant-perching species, diminutive, obsoles- 



