TREE INSECTS AND THEIR CONTROL 185 
Of still greater value is the active cooperation of the local 
authorities in detecting and fighting the insect enemies, 
and this value lies not only in the matter of technical 
knowledge but in the facilities for active combat, as well. 
The owner of a single tree rarely wants to go to the expense 
of buying equipment for spraying and other forms of 
treatment. For the municipal government to handle this 
work for all taxpayers reduces the problem to its simplest 
terms and produces the greatest degree of efficiency with 
the least cost to the individual. 
The importance of municipal treatment of insect pests 
is emphasized by the way many insects spread. It is not 
uncommon for all the trees of a given variety to be affected 
throughout an entire community. Treatment of an indi¬ 
vidual tree in the event of such an epidemic obviously 
accomplishes nothing. The elimination of the visitors 
from that particular tree may be complete, but renewal of 
the attack will be made by emigrants from infested neigh¬ 
boring trees which have not been treated. The only effec¬ 
tual measure is to treat all trees of the infested species, and 
this, of course, cannot be satisfactorily accomplished 
without centralized authority and action. This consti¬ 
tutes one of the unanswerable arguments in favor of mu¬ 
nicipal control for street shade trees, however small the 
community. 
In the absence of a branch of the local government 
prepared for such work, it is important for the individual 
property owners to act in close cooperation among them¬ 
selves, to achieve the best possible results and to minimize 
the cost to each of them. Community ownership of spray¬ 
ing apparatus and other equipment, and community 
action in undertaking to overcome insect attacks, will lead 
to a solution of many of the tree owners’ most serious 
problems. 
