Chapter XIX. 



INSECTS INJURIOUS TO THE JUNIPER. 



Insects Injurious to the Tree-Juniper. 

 Juniperus virginiana. 



affecting the trunk. 



1. The junipek bark-borkr. 



PhlcBOsinus dentatus (Say). 



Order Coleoptera; family Scolytid^. 



Making a short straight primary gallery, with about 15 to 50 longer secondary gal- 

 leries branching from it at nearly right angles, often ending in round holes perforating 

 the bark ; a small white curved grub, changing to a light brown cylindrical beetle. 



We have observed the depredations of this common beetle on the 

 junipers about the city of Providence. The attacks were confined to 

 sickly or dead trees ; whether the cause of death was due to the attacks 

 of this beetle or not could not be ascertain<}d. The beetles were found 

 May 2 and 13 alive in the burrows, which also contained the fully grown 

 larvse, but no pupae w ere observed. In one fallen juniper tree, the 

 trunk of which was about 5 inches in diameter, the mines were unu- 

 sually close together and abundant, fifteen occurring on one side of the 

 trunk in a space about one foot long. Selecting a separate average 

 mine for description, such as is figured in the accompanying engraving, 

 the main or primary gallery is 18™"» to 25""" (1^ to 2^ inches) long and 3""" 

 wide, widening at one end into a trilobed chamber twice as wide as the 

 main gallery. In a gallery 25""" long, including the three-lobed cell, from 

 which no lateral or secondary galleries proceeded, there were forty-eight 

 secondary galleries on one side and fifty-one on the other, the mouths 

 of the opposing tunnels being alternately arranged. The secondary 

 galleries being a little less than one-half millimeter in width ; those 

 arising at each end of the primary gallery are 45'""" long ; those arising 

 near the middle from one-third to one-half and two-thirds as long ; the 

 ends of the tunnels are about '.5""' in width, and they often communi- 

 cate with the hole made by the insect for its exit through the bark, 

 which is 1.5™"' or a little less. These holes are indicated by the round 



904 



