384 THE AMERICAN NATURALIST. [VoL. XXXIV. 
. VIII. ALTERATION OF ENVIRONMENT. 
The blue flag has been less.disturbed by the progress of 
civilization than most native species. Wild trees and shrubs 
and flowers have been uprooted, and cereals and forage crops 
planted in their place, for the farmer coveted their fields. But 
the Iris grows in wet places, not at once available for tillage. 
Yet it has suffered, both directly and indirectly ; directly, 
through artificial drainage, drying up its native shoals; indi- 
rectly, through the influence of the change upon insects affect- 
ing its life history. It would be worth much to know, for the 
sake of comparison, what its relations to insects were before 
the white man came. In the absence of such certain knowl- 
edge there are facts of ecological adaptation which may justify 
an opinion as to some results of the change. To “ civiliza- 
tion " I am inclined to attribute the following phenomena: 
1. The Destructive Abundance of Chetopsis enea Wied. — 
This species is an habitual enemy of the coarser, succulent 
grasses and cereal grains,! boring in their stems. Successive 
broods could not be maintained on the Iris, but the cultivation 
of corn and oats affords it almost unlimited opportunities for 
multiplication. A neighboring cornfield of the preceding year 
may well have furnished the swarms that devastated the Iris 
in locality 8. The scattering growth of the native coarser 
grasses in this region would not be likely to yield such swarms 
any season. 
2. The Injury locally wrought by the Grasshoppers. — These 
were all field and meadow loving species, such as have doubt- 
less become much more numerous in this region since the cul- 
tivation of their food plants was begun. Partial drainage, 
bringing the forage grasses and the flag clumps into closer 
proximity, would encourage the attack. 
3. The Nectar-Stealing of the Pamphilas.—The constant 
presence of large numbers of these butterflies, so well adapted 
for another type of flower, upon the Iris, which is so well 
adapted to another type of insect, furnishes an example of 
1 Vide Howard, L. O. An Ortalid Fly Injuring Growing Cereals, Znsect Life, 
vol. vii, pp. 352-354 (Fig.), 1895. 
