90 Psyche [August 



forms, which have been found to be associated but not so com- 

 monly, include Dendroctonus valens Hopk., Orthotomictis (Ips) 

 coelaius Eich., Dryocoetes americanus Hopk., Hylurgops pinifex 

 Fitch, Gnathotrichus viateriarius Fitch, Cossonus corticola Say, 

 Monohammus confusor Kirby, M. titillator Fabr., Rhagium lineatum 

 Oliv., and Pytho americanus Kirby, occurring principally in the 

 lower trunk region of the pine tree; while Pityophthorus granulatus 

 Swaine, Chrysobothris femorata Fabr., C. dentipes Germ., Pogono- 

 cherus mixtus Say, are occasionally associated in the tops and 

 limbs. 



Two beetles known to be predaceous were found rather com- 

 monly associated with Ips longidens. These are Phyllohoenus dis- 

 locatus Say and Hypophlceus tenuis Lee. One parasitic Hymen- 

 opteron, Ccelopisthus sp. was taken alive from a pupal chamber 

 and there can be little doubt that it is parasite on this bark beetle. 



Hylurgops pinifex Fitch. 



Hylurgops pinifex differs markedly in habit from the preceding 

 in that it is a monogamic form. It attacks white pines by prefer- 

 ence although Hopkins^ 1899, p. 449, records it from other species 

 of pine as well, and Swaine- 1918, p. 81, lists the hosts as "Pines, 

 Spruce and Eastern Larch." Its burrows are constructed in the 

 lower part of standing pines and especially in the stumps of recently 

 cut trees. The burrows have never been found by the writer at a 

 greater height than seven feet from the ground and are more 

 commonly in the lowermost three feet of the base of large thick- 

 barked trees. This region is often heavily infested and the brood 

 very frequently extend their burrows through the bark of the main 

 roots to a distance of 6 or 8 inches under ground. The factor 

 which determines the choice of the bases of trees is not entirely 

 the character of the bark in the region attacked but is apparently 

 the clumsy flight of the adult beetles, for in a number of cases 

 felled trees have been found infested at a distance of 30 feet from 

 their bases in regions where the bark was relatively thin, and in 

 the laboratory the beetles have been induced to breed in similar 

 material. 



The brood-burrows of Hylurgops are radically different from 

 those of Ips longidens or other polygamous forms, the most striking 



» West Virginia Agr. Exp. Sta., Bull. 56. 

 » Loc. cit. 



