102 
failure of the insect enemies of this scale to multiply at a sufficient 
rate to check its rapid increase, and this is possibly the consequence 
of an unfavorable effect of a city environment, although there is 
some reason to suppose that the cottony maple scale has here ex- 
tended northward into a latitude more favorable to itself than to the 
insect enemies which commonly hold it in check. 
Although no attempt has been made to define the present area of 
destructive infestation in Illinois, this scale was reported to me dur- 
ing 1905, in the current correspondence of the office, as locally 
abundant in fifteen counties, namely, Winnebago, Lake, McHenry, 
Cook, Dupage, Kane, DeKalb, Ogle, Bureau, and Henry in northern 
Illinois; Woodford, DeWitt, Sangamon, and Montgomery in cen- 
tral Illinois; and Marion in the southern part of the state. Doubt- 
less the actual area infested by it was much more general than this 
list would indicate. 
The injurious effect of a severe and long-continued drain by the 
cottony maple scale on the vitality of trees infested by it is unques- 
tionable. Many thousands of soft maple, linden, box-elder, and elm 
trees in northeastern Illinois are now dead or dying, or have been 
disfigured by the death of large branches, because of injuries by 
this insect, and large numbers of such trees have been removed. Pri- 
vate citizens, town boards, and park commissioners have become 
deeply concerned, and numerous inquiries and appeals for aid have 
come to this office during the past three years. A lack of available 
funds has, however, prevented as active a participation in the work 
of practical experiment and insecticide operation as might reason- 
ably have been expected of the Entomologist's office, and I ha;ve 
been obliged to content myself, in the main, with improving the 
opportunity to observe, and incidentally to assist, the work of official 
bodies and private parties for the control of this pest. 
I am particularly indebted to Mr. Reuben H. Warder, Superin- 
tendent of Lincoln Park, who has kept me acquainted with his work 
against this and other scale insects, and has made it possible for us 
to follow his operations in detail to their final results. I am also 
under obligations to Mr. O. C. Simonds, Superintendent of Grace- 
land Cemetery, for similar privileges. Our field observations have 
been mainly made by Dr. J. W. Folsom, Associate in Entomology 
at the University of Illinois, and by Mr. E. O. G. Kelly and Mr. 
C. A. Hart, serving as assistants to the State Entomologist. Dr. 
Folsom also managed a small spraying experiment for me at Grace- 
land Cemetery in 1905. 
The present article, in the preparation of which I have had the 
valued assistance of Mr. Hart, is intended to give a brief account of 
