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. ' t 



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 verj'^ 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. 



( Oalerucella 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 

 becomes less numerous and destructive toward the north. In middle 

 Germany it is common, though not especiallj' 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 Housatonic 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 



•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. 



i0356— No. 99—06 2 



