68 



A peculiar and interesting feature of what we may call the primary 

 insect injury is that it is due very largely to native species not previ- 

 ously known to be injurious ; in fact, the principal pine-destroying 

 insect, Dendroctonus frontalis, is even at the present time comparatively 

 rare in collections. Another singular fact is that the invading forces 

 disappeared as suddenly as they came, and, as is usual in such cases, 

 we are as ignorant of the reason for the insects' disappearance as we 

 are of the inducing cause. 



As usual in so many similar instances, these cases of forest-tree 

 injuries were not brought to the attention of entomologists until too 

 late for thorough investigation or experiment. 



December 7, 1891, Mr. W. H. Farley wrote that chestnut trees in 

 Botetourt County, Ya., were suffering from the attacks of wood-boring 

 insects, and although no specimens were obtained it is more than prob- 

 able that Agrilus Mlineatus was concerned. 



The following year Hon. Gardiner G. Hubbard sent a piece of 

 the bark of chestnut from his suburban residence in the district of 

 Columbia from which were reared the ensuing spring specimens of A. 

 Mlineatus. 



During June of 1893 Mr. A. J. Wedderburn, an extensive landowner 

 in Virginia, in the neighborhood of Washington, D. C, reported seri- 

 ous injuries from insects to trees, particularly chestnut and pine, on his 

 property. An investigation as to the cause was requested, and the 

 writer with Mr. W. H. Ashmead was detailed to visit the principal 

 infested locality, which is situated in Fairfax County, about 17 miles 

 from Washington, and now known as Wedderburn. The notes that fol- 

 low are mainly the result of these and subsequent visits that were made 

 in succeeding years to localities in the vicinity of Washington, where 

 injuries to chestnut had been observed, but in spite of every effort no 

 additional facts of value were learned and no opportunity offered for 

 continuing the observations begun in 1893. It was in the hope that 

 the full life economy of the principal depredator, which proved to be the 

 buprestid beetle, Agrilus Mlineatus, might be traced, as well as the 

 causes that led up to the attack of this insect, that the publication of 

 these notes has been deferred. In June, 1896, another visit was made 

 to Wedderburn, but the Agrilus could not be found at this time, and 

 as there is no immediate prospect that an opportunity for the further 

 study and possible solution of the perplexing problem will be afforded 

 it has been deemed desirable that such facts as are available be placed 

 on record. 



BORER INJURY TO CHESTNUT TREES. 



The first visits to Wedderburn were made June 6 and 8, 1893. The 

 principal damage was to chestnut ( Castanea dentata) and scrub pine 

 (Pinus inops), though very general injury to cedar and sassafras was 

 also noticed. 



