INSECTS INJURIOUS TO THE SPRUCE. 229 
under the bark of the spruce. The cells, like those found in the pine 
branches, were situated under the bark of the trunk of spruces 6-12 
inches in diameter, and contained the pupa or more commonly the imago. 
The beetles were found flying about also at this date. 
5. THE RIBBED RHAGIUM. 
Rhagium lineatum Olivier. 
Already described on p. 162, this insect occurred in the larva state in 
abundance under the bark of spruce stumps and standing trees, loosen- 
ing the bark, but never doing any mischief as far as we are aware to 
the living tree. Small larvee, only 4 or 5™™ in length, occurred in spruce 
stumps August 25, while others were 14™™ long. Fully grown ones 
occurred in neighboring pine stumps, and one after having been kept in 
confinement until the last of September went into the pupa state. The 
eggs from which the smaller ones hatched were probably laid in the early 
summer; the trees containing these grubs were cut down in November, 
1880, so that it is not probable that the larva lives more than one year. 
6. THE UNARMED SPRUCE BARK-BORER. 
Xylolerus bivittatus Kirby. 
Order COLEOPTERA; family SCOLYTID. 
This is the most destructive pest of the spruce, the beetle most con- 
cerned in the ravages of spruce forests in northern New England from 
1878 to 1881. We first observed it July 22, 1881, in spruce stumps near 
the Glen House, in the White Mountains, N. H., the tree having evi- 
dently been cut down within a few months; the beetles were very 
abundant, and though there were no perforations in the bark, there 
were small holes between the bark and the wood on the top of the 
stump, the beetles having availed themselves of the shrinkage of the 
bark due to drying of the wood, to effect an entrance between it and the 
wood itself; here they were congregated in abundance and were appa- 
rently engaged in making the primary galleries of their mines and lay- 
Ing their eggs. It was also found under the bark of dead standing or 
fallen spruces. Afterwards (July 27) this bark-borer was found in 
abundance, many larvee, a few pupe, and beetles in great numbers, 
under the bark of partly living and dead spruces at Brunswick. The 
burrows made were small and irregular, slightly larger than the size of 
the beetle, and were much like those made by Xyleborus celatus, with 
which it was commonly associated. It was also found at Merepoint- 
The trees at Brunswick teemed with them, and many fewer beetles than 
those observed would suffice to completely girdle and kill the tree. 
This beetle has its insect enemy; we observed a green chaleid fly un- 
der the bark, July 27, and a month later, August 25, chalcid larve 
nearly fully grown were found under the bark so near the larve of this 
