1907.] The Cottony Maple Scale in Illinois. 



345 



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 

 <ieeply concerned, and numerous inquiries and appeals for aid have 

 <:ome to this office during the past three years. A lack of available 

 iunds 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 have 

 ieen 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 k 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 



