28 



a formative stein is seen, which has short joints that become globular 

 conidia and break apart. Short chains of cells, sometimes showing 

 branches, may often be separated from the mass. The base of the fun- 

 gus mass is stained with a tinge of green, but the stain in the wood is 

 almost black. 



Two species, Monarthrum fasciatum Say (fig. 27) and 

 M. mali Fitch (fig. 28), are confined to the Atlantic 

 forests and range in latitude from 

 Lake Superior to Florida. They 

 have identical habits and feed upon 

 the same fungus. They are com- 

 monly associated in the same tree 

 trunk, and not seldom occupy gal- 

 leries haviug a common entrance 

 hole. Both species are known to 

 attack wine casks, but they proba- 

 fig. 28.— Monarthrum bly breed only in dying trees. 



The trees attacked include oak, 



hickory, beech, maple, aspen, apple, 



and orange, and the list might be extended to include hard-wood timber. 



Monarthrum scutellare Lee. and M. dentiger Lee. are Western species 



of which little is known, except that they have been found in oak timber. 



Fig. 27 . —Monarthrum 

 fasciatum — enlarged 

 (original). 



maK— enlarged (origi- 

 nal). 



THE GENUS XYLOTERUS. 



As in Monarthrum, the males accompany the females in their flight. 

 The young are raised also 

 in separate cradles. 



Xyloterus oivittatus Kirby 

 (fig. 29) is common in con- 

 iferous trees from Alaska 

 to Maine, and extending 

 southward in mountainous 

 regions. It is equally com- 

 mon in Northern Europe. 



Xyloterus politus Say (fig. 

 30) is a smaller, smoother, 

 and unicolorous species in- 

 festing the sapwood of de- 

 ciduous as well as of con- 

 iferous trees. It has a wide 

 distribution in the diver- 

 sified forest region of the 

 Eastern United States. Mr. Schwarz has shown that its attacks may 

 sometimes prove fatal to trees not in vigorous health. It is a dangerous 

 enemy to smooth -barked trees whenever they become weakened by 

 external injuries or shaken by storms. 



Observations made upon maple trees at Washington, D. 0., show that 



Fig. 29. — Xyloterus bivittatus- 

 enlarged (original). 



Fig. 30.— Xyloterus politus- 

 enlarged (original). 



