9 
once if the beauty of the forest and residential districts about Boston 
is to be maintained. The cost of control will undoubtedly be less, 
under efficient general direction by some central authority, than the 
patchy and more or less intermittent work now being done. 
The fact should not be lost sight of that control of the gypsy moth 
will be a continuous charge on the State, towns, and individuals. In 
other words, this insect has now reached a stage when extermination 
is practically impossible. The cost of control will vastly decrease, 
however, once the present excessive infestation is overcome. <A large 
expenditure for two or three years must be expected, after which a 
much smaller sum will be sufficient to locate any important colonies 
which may develop, and effect their substantial extermination. The 
cost of protection in residential districts and on private properties of 
small area should, in a few years, be reduced to almost nothing, if 
good work be done for two or three seasons over the whole area. The 
outlook, therefore, is not necessarily a serious one. Such control, fur- 
thermore, will very largely check the wider distribution of the gypsy 
moth, and substantial protection will thus be afforded to the State of 
Massachusetts and adjoining States. - Even left to itself the moth 
spreads very slowly, as shown by the rather limited area now infested 
after over thirty years of the presence of the pest about Boston. The 
danger from natural spread, therefore, to the State at large and to 
the adjoining States is small. A slow spread must necessarily be ex- 
pected, but with efficient control it will be many years before it widely 
extends its range in Massachusetts. 
Another important step which may be taken looking to the control 
of this pest is the introduction of its natural enemies from Europe and 
Asia. As long as the operations of the gypsy moth committee were 
conducted solely to the end of extermination, it was not especially 
necessary to introduce natural enemies. For the successful introduc- 
tion of these it would have been necessary to have kept undisturbed 
large colonies of caterpillars in which the foreign parasites and pre- 
daceous enemies could multiply. With the object of extermination in 
view this was distinctly undesirable, but now that extermination is 
out of the question it becomes desirable and feasible to make the effort 
to introduce such natural enemies and to leave undisturbed isolated 
colonies of the moth in woodland districts in which these experiments 
ean be conducted. It is well known that in Europe and Asia, the 
original home of the gypsy moth, the pest is not often very destruc- 
tive. Bad colonies will occasionally appear, only to disappear again 
in a year or two. ‘This disappearance and the general inactivity of 
the moth in its native home are doubtless very largely due to the 
efficiency of parasitic and predaceous insect enemies. From the 
studies of European entomologists and foresters, such natural enemies 
are well known. The introduction of these into Massachusetts would 
