Excrement-feeders 



Canthon nigricornis Onthophagus pciuisylvanicits 



Canthon vigilaus Aphodius spp. 



Canthon laevis Geotrupes opacus 



Copris Carolina Euphoria inda, larvae 



As the bunch-grass is very generally pastured, the presence of 

 horses and cattle attracts large numbers of excrement-feeders. As 

 the scavengers are commonly divided into plant scavengers and ani- 

 mal scavengers, according to the origin of the dead material on 

 which they feed, it would be supposed that excrement-feeders should 

 be placed unconditionally in the latter category. As a matter of 

 fact, much of the plant food eaten by horses and cattle passes through 

 the alimentary canal undigested, and the scavengers thus feed to 

 some extent on vegetable material. 



Scavengers belong mainly to the sub-surface and underground 

 strata of the association. They include animals of both selective and 

 non-selective food-habits. Strictly scavenger species are never domi- 

 nant. 



INVADERS FROM OTHER ASSOCIATIONS 



The animals of the bunch-grass and those of surrounding as- 

 sociations always intermingle to some extent, and the invading ani- 

 mals assume a place in the association, and exert an influence in it, 

 much as if they were typical members of it. Often the breeding 

 activity of these animals is restricted to local environments not rep- 

 resented in the sand prairie, as in the case of insects with aquatic 

 larvae. The associations from which invaders are derived most fre- 

 quently are forests and thickets, the cultivated fields, marshy and 

 aquatic situations, and the blowsand association. Alost of the spe- 

 cies from the blowsand are also found in the bunch-grass itself, as 

 interstitial animals, so that the invaders are not readily separated 

 from the true bunch-grass animals. 



( I ) Invaders from forests and thickets 



Diplocardia sp. Buteo platypfenis 



Parajidiis sp. Coccy:;us crythrophtlialnins 



Termcs Haripcs Tyrannus tyrannus 



Ischnoptera sp. Corriis brachyrhyiichos bracJiy- 

 Liiiiojiius qiicrcinits rhynchos 



Scrica scricea Cardinalis cardinalis cardinalis 



Batylc suturalis Laniiis ludoricianus migrans 



Xylopiniis sapcrdioidcs Minius polyglottos 



