THE PINE INVESTIGATION. 



415 



THE TURPENTINE BARK BEETLE. 



Dendroctonus terebrans, Oliv. 



This is the u boring Hylurgus" of Harris' 

 Treatise p. 75; but its characteristic habit 

 of living in turpentine in the bark of pine 

 trees has suggested turpentine bark bee- 

 tle as a more appropriate common name. 



It is worthy of special mention in this 

 report from the fact that it was the 

 species which was first thought to be the 

 prime cause of the death of the pines 

 when in July, 1891, I found it attacking 

 healthy, living trees, also from the fact 

 that it was one of the most common and 

 principle allies of the destructive pine 

 bark beetle. Another feature which ap- 

 pears to entitle it to second place among 

 the insects associated with the trouble, tures and interspaces, 

 is the fact that it was the only species besides the destructive 

 pine bark beetle which was observed attacking and breeding in 

 the bark of vigorous, living trees. 



DESCRIPTIONS. 



Adult. Fig. LXXI1I. See description under the genus Den- 

 droctonus, p. 392, and P'ig. LXI1I. 



Egg, Length, .9 m.m.; width, .5 m.m.; color, white. 



Larva. Fig. LXXV. Length, matured, 8-10 m.m.; width, 2.5-3 

 m.m. ; described by Harris 1 as follows: "short, thick, nearly 

 cylindrical body wrinkled on the back and somewhat curved, 

 and of a yellowish white color with horny, dark-colored head, 

 and destitute of feet." To this I would add, that the large 

 series of larvae in our collection have as the most destinctive 

 character, a horny dorsal plate on the last abdominal segment 

 armed with seven acute spines, four of which are curved. Fig. 



1 Harris' Treatise, p. 85. 



