1919] Blackmail — Notes on Species of Piiyophtkorus 139 



exception of the first few millimeters, are packed full of the detritus 

 derived from the excavation of the burrow. This doubtless is 

 correlated with their unusual length. The egg-niches are spaced 

 at considerably wider intervals than is common with other scoly- 

 tids, seldom being closer together than 4 mm. and often being 

 considerably farther apart. This is especially noticeable in the 

 terminal portions of the longer burrows. It would seem that the 

 female beetle continues to extend her burrows at about the same 

 rate even after her egg laying is nearly or quite completed. 



While absolute proof is not at hand, the evidence indicates that 

 in the latitude of central New York there is but one generation of 

 P. granulatus each year. It is doubtful if this insect is ever injuri- 

 ous. Usually, indeed, it should in my opinion be classed as bene- 

 ficial from the standpoint of forestry, for by preference it attacks 

 trees or limbs which are dying from suppression. In attacking 

 dying suppressed trees, it hastens but little the death of trees which 

 would inevitably soon be lost in any event. On the other hand, in 

 attacking suppressed limbs, it completes the death of these and 

 thus confers a benefit by hastening the natural pruning necessary 

 for the production of good, clear timber. 



Insects found associated with P. granulatus in white pine include 

 Chrysobothris femorata Fabr., C. dentipes Germ., Pogonocheriis 

 mixtus Hald., Leptostylus sexguttatus Say., Pityogenes hopkinsi 

 Sw., Pityophthorus nudus Sw., P. cariniceps Lee, P. puberulus 

 Lee, and the predators, Phyllobanus dislocatus Say and Hypo- 

 phlcpus tenuis Lee. Cocoons of a small hymenopterous parasite 

 have been found at the ends of the larval burrows but the writer has 

 not succeeded in breeding these out. 



Pityophthorus nudus Swaine, 



Pityophthorus nudus Sw. is found in Quebec, Ontario and New 

 York, and breeds in white spruce, Picea canadensis (Swaine, 1917, 

 p. 30). It is very similar to P. granulatus not only in structure 

 but also in habits. The writer has observed it in central New York 

 breeding in small limbs of white pine where it is usually associated 

 with granidatus, although it is here by no means as common as the 

 latter. All our specimens of this species were obtained from limbs 

 less than one-half inch in diameter, although it may occur in larger 

 limbs and tops as well. The engravings made by the insects in 



