7 
In fact, it is safe to say that shade trees suffer especially from insect 
attack throughout the region of country which is contained in the 
Upper Austral life zone.' 
Concerning the borers, it may be briefly said that these insects 
rarely attack vigorous and healthy trees, but should a shade tree lose 
its health through the attacks of scale insects, through rapid defolia- 
tion by leaf feeders, or through a leaky gas main or sewer pipe, differ- 
ent species of borers will at once attack and destroy it. There is one 
particular exception to this rule, and that is the European leopard 
moth, a most destructive species, which is at present of very limited 
range and confined to the immediate vicinity of New York City. No 
certain information is at hand which indicates that it has spread for 
more than 50 miles from the center of introduction. This insect attacks 
healthy trees, boring into the trunks of the younger ones and into the 
branches and smaller limbs of many shade and fruit trees. It is an 
extremely difficult species to fight, and it is fortunate that its spread 
is not more rapid. 
THE IMPORTED ELM LEAF-BEETLE. 
(Galerucella luteola Miill. ) 
Original home and present distribution.—The imported elm leaf-beetle 
(fig. 3) is a native of southern Europe and the Mediterranean islands. 
It is abundant and destructive in the southern parts of France and 
Germany, and in Italy and Austria. This beetle is found, though 
rarely, in England, Sweden, and north Germany, and gradually be- 
comes less numerous and destructive toward the north. In middle 
Germany it is common, though not especially destructive. As early 
as 1837 it was imported into the United States at Baltimore, and is 
now found as far south as Charlotte, N.C. From this point it ranges 
northward in the Atlantic cities as far as Providence, R. I. Inland it 
has not passed the barrier of the Appalachian chain of mountains, and 
is practically confined to the Upper Austral region, as indicated in the 
map on page 210 of the Yearbook for 1894. Thus, up the Hudson 
River it has spread to Albany, N. Y., but on either side of the river, 
as the land rises into the foothills, it has stopped. In the same way 
it has more recently spread up the Connecticut River Valley to a point 
north of the New Hampshire State line, and also, to a less extent, up 
the Ilousatonic Valley. From our present knowledge it seems likely 
that its future spread as an especially destructive species will be lim- 
ited by the northern border of the Upper Austral region, and that (as 
may happen at any time) should it once be carried by railway train 
across the southern extension of the Transition life zone, caused by 
the Alleghany and Blue Ridge mountains, it will spread unchecked 

| Briefly defined by Dr. Merriam in his summary article on ‘‘The geographic dis- 
tribution of animals and plants in North America,” in the Yearbook of this Depart- 
ment for 1894, page 203. 
