27 



Maine. Tt lielongs to tho same family of beetles as the true destroj'el*, 

 but to an entirely different genus. The sj)ecitic name, rufipemiis, 

 given to it b}^ Kirby, is unfortunately the same as that he gave to the 

 Dendroctonus described from the same region. This has caused 

 much confusion in the writings of entomologists and others relating 

 to the insect enemies of the spruce. 



This species is enormously abundant in all injured and dying stand- 

 ing trees, and in the bark of the branches, tops, and stumi)s, in 

 cuttings, wiudfalls, etc. (PL VIII, e, and PI. IX.) Its abundance, 

 togethei- with its hal>it of infesting the tops of trees immediately after 

 tlie middle portion of the trunk or ])ase has been attacked by the 

 spruce-destro^dng beetles, renders it one of the most efticient allies 

 of the primarj^ enemy. 



The adult is a small black beetle about .08 of an inch long aiul .01 

 of an inch broad. It is easily distinguished from all other spruce 

 bark beetles of similar size and form by tlie fact that each of its com- 

 pound eyes is divided b}^ a smooth narroAv space. It passes the win- 

 ter in all stages within the bark of spruce stumps, logs, and the tops 

 of felled and standing trees.' 



THE SPRUCE TETROPIUM. 



Tliis is the round-headed bark and wood-miner which was found to 

 be so common in the spruce of Westi Virginia in 1891, where its work 

 contributed to the rapid decay of the wood of dead trees. "^ It is very 

 common in the spruce of Maine, where it was observed by the author 

 in the stumps and logs of recently felled treos and toward the base 

 of trees attacked by the spruce destroyer. Indeed, an attack l)y the 

 latter is followed almost immediately by the Tetropium adult, which 

 deposits its eggs in the outer bark from toward the middle of the 

 trunk to the base. The young larva? are capable of mining through 

 the living bark (PI. X) and continuing their work regardless of the 

 sap and pitch. Therefore, this insect must be classed as one of the 

 principal aids to the spruce beetle in not only causing the death of 

 the trees, but in contributing to the rapid decay of the wood. 



OTHER INSECTS. 



Numei'ous other insects which aid in causing the death and decay 

 of spruce might be mentioned (Pis. VIII, XI, and XII), but the two 

 just referred to are by far the most important. There may, how- 

 ever, be an exception in the defoliating insects (PI. XIII), which, it 

 is believed, maj^ contribute greatly to produce favorable conditions 

 for the attack of the spruce-destroying beetle. 



' For a more detailed account of this beetle see Bnlletin 56, W. Va. Agricultural 

 Experiment Station. "Report on Investigations to Determine the Cause of 

 Unhealthy Conditions of the Spruce and Pine, from 1S80 to 189;), "" pp. 240-251. 



'' Ibid., pp. 239-242, 259, 438. 



