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 other 
ornamental trees as well, where tli^se are grown in rows or groups 
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 our 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 wel- 
come 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 histoi-y 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 over most of it, the maple 
scale has l)een 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 
cessation of its injuries and its virtual disappearance from the trees 
infested by it have seemingly been due almost wholly to the agency 
of its insect enemies. 
An exception to these statements is presented bv 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 vege- 
tation, 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 
*Pulviiia>ia inuumi-rahiHs. 1 Acer saccharinum. 
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