468 ANNUAL REPORT OF NEW- YORK 



CHESTNUT. TRUNK. 



15. THE CHESTNUT.— Ca^/anea vesca, 



AFFECTING THE TRUNK AND LIMBS. 



We have never noticed any boring insect of a large size in the 

 wood of this tree. But the durability of its timberj which is so 

 highly valued, particularly for fence rails and posts, is much im- 

 paired by small insects which perforate it with holes that are only 

 of sufficient size to admit the head of a pin, but which are often 

 excessively numerous, and being pierced directly inward towards 

 the heart of the tree become filled with wet from every shower. 

 The decay of the vrood is hereby greatly accelerated. These per- 

 forations are made by a slender cylindrical six-footed worm, half 

 an inch long, of a white color and brownish yellow at each end, 

 its apex cut off abruptly and obliquely and edged with small 

 black teeth. The beetle that is produced from this worm is not 

 yet ascertained. 



Eails which have been pierced with pin-holes by this insect 

 should always be placed in the fence with their sap side down- 

 wards, as it is upon this side that these holes mostly open. 



195. Two-toothed Silvanus, Silvanus bidentatus, Fab. (Coleoptera. Myce- 

 tophagidae.) 



Under the bark of logs and decaying trees, probably loosening 

 the bark from the wood, a minute, narrow, flattened beetle, of a 

 light chestnut-brown or rust-color, its thorax longer than wide, 

 slightly narrowed towards its base and with a small tooth pro- 

 jecting outwards at each of its anterior angles. Length 0.10 to 

 0.12. 



This is a European insect, which, like a kindred species, the 

 Sui'inam Silvanus, has now become perfectly naturalized and as 

 common throughout the United States as it is in its native haunts. 

 On stripping the bark from recently cut logs of chestnut and of 

 oak, this minute beetle, which is so flattened and thin that it can 

 creep into the slightest crevices, will be found frequently in con- 

 siderable numbers. We have several other insects which inhabit 

 similar situations and are so much like this that a careful exami- 

 nation is requisite to determine their respective species. By the 



