484 The American Naturalist. _ [Sune, 
conditions effecting these movements, principal among them 
being a break in the interrelation of food supply, or improper 
conditions for the carrying on of propagation. The unusual 
appearance of insects in a given locality, classed under the 
category of primary or “ local flights,” are met with occasion- 
ally by observers. One of considerable moment is set forth in 
the following narration: On the nineteenth of September, 
1893, the Grouse Locust, with a few other members of Acridi- 
de, striking out for more favorable conditions, landed at night 
in swarms in Chicago. The writer noticed them everywhere 
in the city. The small size of this locust (9, ¢—12-16 mm.) 
in length, with peculiar inconspicuous colors, caused them to 
be overlooked by the people passing the next day who, with- 
out being conscious of the fact, crushed thousands under their 
feet, leaving tiny stains upon the sidewalks. Again, two days 
following their first appearance, on the twenty-first inst., mul- 
titudes of Grouse Locusts dropped during the night. As 
individuals, they were comparatively large and vigorous. 
Many were taken to indicate the range of flights; specimens 
being recorded at scattered points. A region covering, not 
only the City of Chicago, but the northeastern portion of 
Illinois and that part of Indiana including the lower bend of 
Lake Michigan adjacent, as shown in the accompanying map 
Fig. 4, was represented. Observations in the city showed that 
the electric arc lights, to which they were attracted, killed off 
large numbers, while the stretch of waters in the lake 
destroyed others. ; 
Through the streets, in the heart of the city, the writer col- 
lected in a short time, twenty-seven specimens, comprising 
thirteen males and fourteen females, showing a remarkably 
even distribution of sexes. A significant point indicating 
direction from which they came was gathered from the fact 
that most, if not all the specimens, when examined, 0n the 
streets running east and west, were on the north side of the 
street, showing that they were blown against the tall buildings 
and then dropped to the ground. Information received from 
Mr. H. C. Frankenfield, local forecast official, who kindly a 
ored the writer with a report, giving the direction of the wih 
