ENEMIES OF EVERGREEN OR CONIFEROUS TREES 



WORK OF BARK BORERS IN PINK 



It is difficult for the average reader to gain a just conception of the 

 injurious character of these insects by a perusal of a number of detached 

 notices of the work of associated species. It is therefore proposed to give 

 at the outset a brief resume of the conditions we have found in the Hudson 

 valley. The white pines in this section have suffered seriously during the 

 last three or four years and a considerable proportion of the damage is 

 due to the work of bark borers and their associates. The extremely 

 injurious character of their operations is well illustrated on plates 52, 

 53 and the rapid progress these pests may make is shown in figures 1 

 and 2 of plate 53. Figure 1 was taken Sep. 28, 1901 and figure 2 of the 

 same trees was taken April 1902. It will be seen that these pines have 

 been practically killed within a year and if a close examination is made we 

 will find conditions substantially as follows; 



At the very base of the trees there are a number of irregular, rather 

 large masses of pitch and on removing these it will be found that they 

 cover the entrance to a gallery about ^ inch in diameter. The condition 

 within is well represented on plate 58, figure 4, which shows the preserva- 

 tion of the walls by the infiltration of pitch and is thus incontrovertible 

 evidence of living tissues having been attacked. This borer, known as 

 Dendroctonus terebrans Oliv., is a very common species in New 

 York State where it may be met with in small numbers in almost any pine 

 grove. It can hardly be regarded as a dangerous form though it works in 

 living tissues. Farther up the same trees a much more serious injury is 

 evidenced by the numerous pitch tubes on the bark [pi. 54, fig. 2]. Plate 

 54, figure 4, represents one in profile. The removal of a piece of bark 

 will show the condition of affairs under the pitch tube. Plate 54, figure 

 3, illustrates the large central chamber underneath with five longitudinal 

 galleries leading therefrom. Small notches may be observed on the sides 

 of these galleries, particularly near the extremities, ar.d these lead into 



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