486 The American Naturalist. | [June, 
seen from the following observations. On September 16, 1899, 
it was observed that the large stream at Riverside, a few miles 
west of Chicago, was so low that in many places one could travel 
across on the limestone bed, a thing before impossible. Aloug 
the banks of this stream Orthoptera appeared uneasy and 
much affected by the heat prevailing at the time. To the 
southeast and southwest, the directions from which the Grouse 
Locusts were blown, for miles the broad stretch of marshes, 
sloughs, small streams, ponds and lakes were dried, changing 
decidedly the topography of the districts. The effect upon 
animal life was to cause the shifting about of many kinds. 
The young grasshoppers, unusually favored, passed on to 
maturity aided by a scarcity of birds, their natural enemy, 
moreover, circumstances on every side being favorable, allowed 
excessive numbers to develop. Multitudes infested the regions 
where usually a few existed. By late fall the soil was baked 
by the heat, giving rise to a difficulty in finding a suitable 
place to deposit their eggs. Later, still further changes were 
enacted, for those habits ordinarily sedentary, now took on a 
tendency to be nomadic. Simultaneously, a kind of restless 
irritation took possession of the insect. Rising in the air 1n 
short flights to rid themselves of distress, aimlessly they pursued 
these movements through the day seeking for shelter. Æ 
long, a wind rushing in to take the place of the rarefied all, 
moving upward, bears off to distant points those caught up 10 
its irresistible powers. Upper air currents may blow from 
three to twenty miles an hour, so basing an estimate on these 
grounds, a day’s flight may be approximated at from twenty 
to one hundred miles. When subjected to a test the Grouse 
Locust’s flight, ordinarily, is quite prolonged, being swift and 
noiseless. Referring again to the map Fig. 4, (shaded por 
tion) an idea may be gained of the local flights of this little 
locust. If the furthest point be placed at one hund. 
miles distant from Chicago, the local point of observation, 
taking into consideration also the specimens found, the section 
of northeastern Illinois including the Kankakee River and 
its branches, the outlying marshy districts, various streams, 
ponds and tributaries of the Illinois River and the section 
Re ees a hae 
