10 U. S. DEPARTMENT OF AGRICULTURE BULLETIN NO. 484. 



Backberry {Celtis occidentalis Linn.). 

 Holly, American (Ilex opaca Ait.). 

 Laurel, Mountain (Kalinin I<i1if<ilia Linn.). 

 Locust, Black (Robinia pseudacacia Linn.) 

 Locust, Honey (Oleditsia triacanthos Linn.). 

 Maple, Mountain {Acer spieatum Lam.). 

 Maple. Striped (Acer pervn&ylvanicum Linn.). 

 Mulberry, Red (Morns rubra Linn.). 

 Nheepberry {Viburnum lent ago Linn.). 

 Sycamore (Platamis occidentalis Linn.) 

 Tulip (Liriodendron Udipifera Linn.). 

 Walnut, Black (Juglans nigra Linn.). 



Shrubs occur frequently as undergrowth in the woods of the in- 

 fested region and may have an important bearing on the infestation 

 of the trees growing above or around them. A stand of such species 

 of trees as are not fed upon until the larvae reach their later stages 

 might be immune from damage were it not that the larvae are en- 

 abled to reach these later stages by feeding on near-by shrubs. Most 

 of the shrubs which grow in the region die out if sufficiently shaded, 

 and the balance occur so rarely in shade or are eaten to such a slight 

 degree by gipsy-moth larvae that they are unimportant. If forests 

 were under management the danger of woods thus being infested 

 would be eliminated, because in a properly managed forest the trees 

 should be so grown that they produce at all times an amount of 

 shade sufficient to preclude the development of shrubs in any numbers. 



Larvae feeding on shrubs which are favored food plants, occurring 

 in open land adjacent to woods, might migrate to the woods, but 

 would not penetrate very far if the trees of the stands were of any 

 but those of Class I. 



The following statement appears on page 27 of Bulletin 250: 

 " There is in some cases, at least, considerable variation in suscepti- 

 bility of different trees of the same species." This should be con- 

 sidered carefully in connection with any form of management which 

 prescribes the removal of certain trees on the ground that they are 

 liable to infestation. 



PRECAUTIONS NEEDED. 



Natural enemies of the gipsy moth, in particular those introduced 

 from abroad, are constantly increasing in numbers, and their influ- 

 ence is a large factor in the control of the moths in woods. It is safe 

 to assume that this increase in numbers is going to continue and that 

 in the future the character of gipsy-moth damage to woods will 

 thereby be greatly modified. 



In view of the above, and of the fact that it is impossible definitely 

 to predict the outcome of an infestation under any circumstances, 

 it is unwise to attempt to eliminate any particular species out of 

 consideration for susceptibility to gipsy-moth attack alone. There 



