72 BULLETIN 234 



from galls which were quite common in Michigan on a willow (Salix discolor}. Davis 

 describes these galls (Insect Life, IV, p. 66) as an oval swelling of the live branch in 

 which the borer tunnels "an oval gallery downward from the gall, sometimes in the pith, 

 but oftener indiscriminately through the wood, and makes its exit often an inch and a half 

 below." This work in willow is so different from that of Agrilus auxins in birch, that I 

 was inclined to doubt the identity of the two borers, but an examination of one of Cook's 

 specimens convinced me that they are probably the same insect, and Mr. E. A. Schwarz 

 confirms this. As the specimen was a female, it was impossible to determine it definitely. 



In 1896, Jack reported (Garden and Forest for 1896, p. 269), that " some of the foreign 

 birches in the Arboretum and other localities about Boston have been killed by the attacks 

 of boring larvae " which were doubtless this Bronze Birch Borer. About the same time 

 the white birches in the parks of Buffalo began to die from the attacks of this pest, and 

 during the past six years the insect has killed hundreds of these beautiful trees in Buffalo, 

 Rochester, Hornellsville, Ithaca and doubtless other cities in New York ; and similar 

 destructive work is reported from Detroit and Ann Arbor in Michigan, from Chicago, and 

 from Guelph, London and Hamilton in Canada. It is still continuing its ravages in some 

 of these cities, slowly spreading from tree to tree, as practically no well directed effort is 

 being made to check it. 



A good summary of previous records of the insect and an account of its work in Buffalo 

 was given by Chittenden in 1898 and 1900 (Bull. No 18, new series, U. S. Div. of Entomology, 

 p. 44-51, and Bull. 22 of the same Division, p. 64-65). In apaper on " A Disease of the 

 White Birch" read in March, 1901, before the Michigan Academy of Science (3rd Rept. of 

 Mich. Acad. Sci. 1902, p. 46-49) John Larsen gave an excellent account of many original 

 observations on the work and habits of this insect. Professor Lochhead well summarized 

 the records in 1903, (28th An. Rept. Ontario Agr. Coll. & Exp. Farm for 1902, p. 22-23). 



THE DISTRIBUTION AND DESTRUCTIVENESS OF THE INSECT 



This bronze birch borer is an American insect and is widely distributed 

 throughout the northern United States and Canada. It has been recorded 

 from New Hampshire and Massachusetts westward through Connecticut, New 

 Jersey, New York, Pennsylvania, Virginia, Quebec and Ontario in Canada, 

 Michigan and Illinois to Colorado. Thus far it has been reported as injurious 

 only in Massachusetts, New York, Michigan, Illinois and Ontario in Canada. 

 But doubtless many white birches in other States have been killed by the 

 insect, the real cause being unknown or unrecorded. 



In New York state this borer now occurs in destructive numbers in St. 

 Lawrence County, and in the following cities : Buffalo, Rochester, Ithaca, 

 Hornellsville, and probably others. The beetles have been taken in other 

 parts of the State, and it is liable to appear in destructive numbers wherever 

 white birches are used as ornamental trees. 



In Europe two similar borers (Agrilus betuleti Ratz. and Agrilus viridis 

 L.) are destructive to birches. 



The fact that the bronze birch borer often kills large trees in three or 

 four years is sufficient evidence of its very destructive character. Within a 

 few years many white birches in Chicago, Ann Arbor, Detroit, Buffalo, Ithaca 

 and other cities have been killed by the insect. A tree usually succumbs 

 within two or three years after the first top branches die. 



In 1895, M. F. Adams, a keen observer of insct life, discovered that 



