IXDIRECT INJURIES CAUSED BY INSECTS. 211 



trees, may have been originally produced by the bite 

 or incision of insects. 



Besides exterior insect enemies, living trees are liable 

 to the ravages of many that are interior. The cater- 

 pillar of the great goat-moth (Bombj/x Cossus^ F.), of 

 the hornet-hawk-moth (Sesia crabroniformis^ F.), and 

 of two beetles {Nitidula grisea, F., and Ciirculio La- 

 pathi. L.), devour the wood of the willow and sallow, 

 which thus in time often become so hollow as to be 

 easily blown down. The bee-hawk-moth (Sesia api- 

 formis, F.^), and probably R?/nchites Populi, a bril- 

 liant green weevil, feeds upon the poplar — Prionus 

 coriarius is sometimes found in the oak and sometimes 

 in the elm, and Bostrickus Pini, F. in the Scotch fir. 

 When the sap flows from wounds in a tree it is attend- 

 ed by various other beetles, (I have observed Cetonia 

 aiirata^ F., and several Nitidulce and Staph?/ litii dee busy 

 in this way,) which prevent it from healing so soon as 

 it would otherwise do ; and if the bark be any where 

 separated from the wood, a numerous army of wood- 

 lice, earwigs, spiders, field-bugs, and similar subcor- 

 tical insects take their station there and prevent a re- 

 union. 



The mischief however produced by any or all of 

 these, is not to be compared with that sometimes sus- 

 tained in Germany from the attacks of a small beetle, 

 (Bostrickus T?/pographus, F.,) so called on account of 

 a fancied resemblance between the paths it erodes and 

 letters, which bores into the fir. This insect, in its pre- 

 paratory state, feeds upon the soft inner bark only : 

 but it attacks this important part in such vast numbers, 



^ Lewin in Linn. Trans, iii. 1. — Curtis in do. i. 86. 

 P 2 



