20 BULLETIN 204, U. S. DEPARTMENT OF AGRICULTURE. 
RESULTS OF EXPERIMENTAL WORK. 
Many of the experimental projects which have been undertaken are 
nearing completion and detailed reports will be published later. 
The information on food plants will now form a definite basis for 
practical work, and as has been brought out by the observations in 
Europe on both parasites and food-plant conditions, it will be neces- 
sary to bring about in our forests a great reduction of the favored food 
plants of the gipsy moth before natural enemies can be expected to 
keep this insect within reasonable boimds. 
The parasites and wilt disease, as has already been shown, are doing 
effective work, but the results would be greatly amplified by eliminat- 
ing favored food plants. 
The study of the increase of the moth in the field furnishes valuable 
data on all phases of the forest control problem, while the work on 
dispersion is of special value in connection with the field control work 
which is being carried on. 
Secondary insects are important inasmuch as they may prevent the 
recovery of many trees which have been defoliated and which would, 
under normal conditions, gradually recover. 
SILVICULTURAL WORK. 
During the time the gipsy moth has been known to exist in this 
country it has done an immense amount of damage to tree growth of 
the infested region. The injury has caused the death of many of the 
trees attacked or the retardation of their growth and development, 
and has produced conditions favorable to the increase of secondary 
enemies. The tree growth affected may be divided into three classes, 
(1) fruit trees, (2) shade or ornamental trees, and (3) forest trees. 
All have suffered severely, but owing to their greater value and 
relatively smaller numbers- it has been possible to prevent a large 
amount of the injury b}^ applying hand methods of suppression to 
fruit and shade trees. Gipsy-moth damage to forest trees, however, 
can not be controlled in the same way owing to the great expense 
involved, hence the problem of preventing damage in woodlands is a 
serious one. In some European countries this has been solved to a 
considerable extent by growing species which are not so susceptible 
to gipsy-moth attack. The investigations on the food plants and 
feeding habits of the gipsy moth indicate that the work of eliminating 
the most susceptible and encouraging the growth of those that are 
not favored as food by this insect is likely to give good results. As 
this work involves, to a considerable extent, the practice of silvicul- 
ture, the Bureau of Entomology requested and received the coopera- 
tive assistance of the Forest Service, and these two branches of the 
Department of Agriculture are now working together on this problem. 
Mr. George E. Clement, who was formerly an assistant in the Forest 
