THE COTTONY MAPLE SCALE IN ILLINOIS. 



The cottony maple scale* is a native insect parasite of the soft 

 maplef , rarely if ever injurious to the scattering trees of this species 

 growing in natural forests, but so destructive to them, and to otljier 

 ornamental trees as well, where these are grown in rows or grotips 

 along streets or in parks and on private lawns, that its control has 

 become an object of primary importance to all owners and lovers of 

 some of pur most beautiful and popular American trees. In and 

 about Chicago especially, it has destroyed, within the past five years, 

 thousands of trees, beautiful and valuable in themselves, and still 

 more highly valued because of the associations attached to them. To 

 do our best to save these noble but helpless products of nature from 

 a slow and unsightly death by parasitic disease, must be the welcome 

 duty of all who appreciate the significance of trees in the life of 

 the people, and especially of those who live in our larger cities. 



The history of this insect in Illinois since 1867 exhibits succes- 

 sive periods of abundance and of scarcity, each averaging about four 

 or five years for the state as a whole. That is, throughout some 

 considerable part of the state, and often dvei" riiost of .it, the maple 

 scale has been injuriously abundant once in eight or ten years, and 

 its period of abundance has lasted, as a rule, about half this time. In 

 any given locality, however, it has usually been injurious for a much 

 shorter time, often for not more than one or two years. The cessa- 

 tion of its injuries and its virtual disappearance from the trees in- 

 fested by it have seemingly been due almost wholly to the agency 

 of its insect enemies. . 



An exception to these statements is presented by the existing 

 outbreak of 'this insect in northeastern Illinois, and especially in 

 Chicago and its suburbs to the north and west. Here, as shown by 

 observations of assistants of the office who have been repeatedly sent 

 through the park and boulevard systems of Chicago for an investi- 

 gation of insect injuries to shade trees and other ornamental vegeta- 

 tion, it has certainly been destructively numerous since 1901. 

 Indeed, according to information locally given to Mr. H. E. Weed, 

 of Chicago, it has been continuously injurious over some parts of 

 this area since 1886. This general persistence of an injurious in- 

 festation within the same district for so long a period is due' to the 



*Pulvinaria innumerabilis. iAcer sacchariiium. 



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