THE BRONZE BIRCH BORER y t 



and must have kept the little creature chewing nearly every moment of the 

 four months. 



Oftentimes on the trunk and larger branches the burrows of several 

 borers zigzag across each other in interminable confusion, as shown at a in Fig. 

 36. Yet it is a remarkable fact that even in this case where the infestation 

 was very severe, there were no indications on the bark of the trunk of any 

 injury beneath, or that the tree was infested by a borer ; this fact is well shown 

 in Fig. 33, where small portions of the bark were removed and the numerous 

 burrows of the borer revealed. The burrows mostly extend through the grow- 

 ing wood just beneath the bark, and often the effort of the tree to repair the 

 injury results in a woody growth over the burrow that causes corresponding 

 ridges to appear on the bark (Fig. 30, ). Sometimes a burrow can be 

 traced for several inches by these ridges on the bark. The next year's 

 growth of the tree may cover an old burrow with wood, and burrows have been 

 found thus buried under three annual rings of woody growth, showing that the 

 tree might overcome some of the injury were it not for renewed attacks by the 

 pest. Sometimes the burrowing of the borers weakens the limbs to such an 

 extent that they break from their own weight. 



HISTORICAL NOTES 



Scientific name. The first record in the literature of this Bronze Birch Borer concerned 

 its scientific name. Like many other American insect pests, this borer was also named in 

 Europe. One of the adults or beetles found its way into the collection of Dejean, a 

 Frenchman, who published lists of the beetles he had. In the third edition of his Catalogue 

 des Coleopteres (p. 63) issued in 1836, he listed this birch borer, giving it the name of 

 Agrilus anxius. But the honor of naming the insect is now credited to Gory, another 

 Frenchman, who first published in 1841 a description of it and courteously used Dejean's 

 name (Hist. Nat. des Coleopteres, Monog. des Buprestides, Vol. 4, p. 226). Dejean 

 recorded the insect from Boreal America. 



In 1859, the insect was first recorded in American literature by Le Conte, and was then 

 described under two different names as Agrilus gr avis, from Lake Superior and New York, 

 and Agrilus torpidus from Lake Superior and Illinois (Trans. Am. Phil. Soc., XI, p, 247) ; 

 he recorded Agrilus anxius from Massachusetts. The former names fell as synonyms of 

 Gory's earlier name of anxius when Dr. Horn monographed the genus Agrilus in 1891, 

 (Trans. Am. Ent. Soc. XVIII, p. 277-366. 



Early economic records. Dr. Lintner was the first to record anything about the habits 

 of the insect. In 1883, he collected 62 of the beetles "which were observed alighting 

 from their flight in the bright sunshine, and running actively in jerking motions, over the 

 bark upon some cut poplars piled by the wayside" in the Adirondack Region of New York. 

 He suggested that the larva was probably a borer in poplar (37th. An. Kept. N. Y. State 

 Mus. Nat. Hist. p. 50.; the same account occurs in Lintner's fth Kept. p. 281). In 1884, 

 Harrington took specimens of the beetles on willows in Quebec (Can. Ent. Vol. XVI, p. 

 101), and in 1889, Blanchard recorded it as occurring on the foliage of poplar sprouts in 

 Massachusetts, and he took a few specimens on the summit of Mt. Washington, N. Hamp., 

 whither they had flown from below " (Ent. Am. Vol. V, p. 32). 



The first notice of this borer attacking birch appears to be that of Schwarz who men- 

 tioned the insect in 1890, in connection with the work of a Scolytid beetle, Xyloterus poli- 

 tus (Proc. Ent. Soc., Wash., Vol. II, p. 78) at Detriot, Mich., where two silver birche* 

 were killed. The same year Cook ( 3 rd An. Kept. Mich. Expt. Sta., p.i 19), bred the insect 



