16 MAN AND ANIMALS 
b) Communities of parks and pastures.—The ground and subterranean 
animals of both pastures and lawns are (near Chicago) chiefly such 
prairie animals as can live under the conditions of close grazing or close 
mowing. This type of community is probably better developed in 
the pastures than in the parks and lawns. The thirteen-lined squirrel, 
the May beetle grub, and the earthworms are among the common 
species. On the lawns a few grass-feeding species have a hazardous 
existence. On the pasture land prairie animals are more abundant, 
and an occasional prairie bird nests in a clump of weeds which the cattle 
have not eaten. 
Shrubs, when present, are inhabited by the forest-margin species. 
The trees present are inhabited by such forest animals as are able 
to live without the characteristic ground conditions of a forest and 
under the more severe atmospheric conditions. There are various 
facts pointing to a difference in the animals attacking trees differently 
located with respect to other trees; for example, trees standing alone 
in open pastures probably have a very different fauna from trees of 
the same species growing in the woods. This has not been fully investi- 
gated, however. The trees of the parks and lawns are often somewhat 
different from those of pastures, because of the introduction of many 
trees not native to the region. The animal communities of trees fre- 
quently include species introduced from Europe. 
c) Communities of lands devoted to cultivated annuals —The communi- 
ties of farm lands are made up of animals from the prairies, the forest 
margin, and marsh vegetation, together with introduced species, such as 
the cabbage butterfly, the wheat aphis, the Hessian fly, etc. 
d) Communities of orchards —The communities of fruit-growing lands 
are made up of the animals from the wild haw, wild crab, wild plum, and 
other forest trees, the greater number of which are commonest on flood- 
plains. There are also a number of introduced species. 
e) Communities of buildings —The communities of barns, factories, 
and dwellings include the common bedbug (introduced), the silver fish, 
the cockroaches (introduced), various buffalo bugs of which several are 
introduced; one (Dermestes lardarius Linn.) is dangerous to stored 
materials and has been known to eat holes in lead pipe; while various 
spiders, centipedes, and camel crickets occur. The house mouse, the 
Norway rat, and the English sparrow have all been introduced. About 
75 household species are to be expected in and about Chicago. 
f) Communities of polluted waters—In connection with the building 
of cities, we always find the introduction of sewage and industrial wastes 
