326 



YEARBOOK OF THE DEPARTMENT OF AGRICULTURE. 



The extensive development within recent }^ears of the industry of 

 manufacturing tannin extract from chestnut wood has made a market 





FIG. 39. Work of the Columbian timber-beetle: "Steamboats" in quartered or split white oak. 

 (Adapted from author's illustration.) 



for a large quantity of "wormy" chestnut wood in some sections of 

 the country. Indeed, it is said that the wood which is badly perfo- 

 rated with the wormholes is just 

 as good for the purpose as the 

 uninjured, if not better. 



CARPENTER-WORM INJURIES TO OAK 

 AND LOCUST. 



The very large oblong worm- 

 holes (fig. 37) commonly met 

 with in the heartwood of red 

 oak and other oak trees, and 

 also in that of the black or }^el- 

 low locust, is usually the work 

 of the so-called carpenter worm 

 (Prionoxystm robinise Peck). 

 The larvse are large white and 

 pink caterpillars which hatch 

 from eggs deposited by stout- 

 bodied, short-winged, gray 

 moths. The caterpillars often 

 attain a length of 3 inches and 

 a diameter of over half an 

 inch. The holes made by them 

 through the heartwood of the 

 best part of the trunk are some- 

 times li inches in diameter one 

 way by three-fourths of an inch 

 the other, thus causing serious 

 damage to the wood. These, 

 with other large wood-boring 

 grubs of beetles, sometimes 

 infest the top part of the trunk 

 and larger branches of oak trees, where their continued work results 

 first in the dead and so-called "stag-horn" top, and subsequently in 



m 



ict. 40. Work of the Columbian timber-beetle in 

 tulip wood "calico poplar." (Original from 

 photograph.) 



