SOME IMPORTANT INSECTS OF ILLINOIS 
SHADE TREES AND SHRUBS 
By STEPHEN A. FORBES, state entomoi^ogisx 
The protection of the shade trees and ornamental shrubs of 
Ilhnois against insects has been for several years a problem of rap- 
idly increasing importance. Many of' our most desirable trees 
and shrubs are liable to slow destruction by obscure insect 
pests understood little if at all by those immediately con- 
cerned. Trees which have grow^i for years, becoming more at- 
tractive, more valuable, and more highly valued year by year, begin 
to weaken and decay, the owner does not know why. This is often 
due to borers or to scale insects, the presence of which has not been 
detected or suspected, but whose injuries might have been prevented 
if the facts had been known in time. More sudden losses are fre- 
quently caused by overwhelming attacks of leaf-eating insects 
which, altho conspicuous, are not dealt with because proper measures 
of procedure are not known. Observations and experiments upon 
this subject have been for several years a prominent part of the work 
of the office. Beginning in 1898, repeated careful examinations 
have been made of the trees and shrubs of the parks and boule- 
vards of Chicago, and this work has been extended from time to 
time to other cities and towns thruout the state. With the estab- 
lishment of a field assistant in Chicago in 1907, the subject received 
more continuous attention at the hands, first, of Mr. H. E. Hodg- 
kiss and, later, of Mr. John J. Davis, the latter of whom espe- 
cially has made many studies of the life histories of species previ- 
ously but little known, and has added a mass of details to our 
knowledge of the subject in all its parts. 
The general subject is still under investigation, and will be in 
due time reported upon in a much fuller and more elaborate article, 
but the present brief preliminary paper has been prepared in the 
hope that it may be found of immediate practical use to municipal 
authorities in control of parks, boulevards, and streets, to town im- 
provement societies, and to owners of lawns and other private 
premises the appearance of which they are striving to improve by 
the use of trees and shrubs. 
