229 



means of wires, and the bark is lacerated to produce a 

 rugged character. One branch is partly broken through, and 

 allowed to hang doAvn as if by accident ; another is muti- 

 lated to represent a dead stump. This treatment produces, 

 in course of time, the appearance of an old weather-beaten 

 forest-tree, and it is then, if unworthy of all the pains 

 that have been bestowed upon it, certainly a curious object. 

 Several insects prey on the Elm ; among which by far 

 the most mischievous is the Elm-destroying Beetle {Scolytus 

 destructor). The ravages committed by this minute insect 

 would scarcely be credible, 

 were we not informed that 

 as many as 80,000 have been 

 found in a single tree. Two 

 eminent entomologists, Mr. 

 Spence in England, and M. 

 Audouin in Erance, have 

 turned their attention to 

 this subject, and have satis- 

 factorily shown the impor- 

 tance of watching the habits 

 of an insect less than a quar- 

 ter of an inch in length. 

 The result of their obser- 

 vation is that the perfect in- 

 sect feeds on the inner bark of the Elm, to reach which it 

 perforates the outer bark, and feasts at its leisure. The 

 cavities thus made interrupt the ascent and descent of 

 the sap, and retain moisture, from the combined effect 

 of which causes the tree, in the course of a few years, 

 becomes sickly, and is brought into exactly that state in 

 whiich the female selects it for laying her eggs; though 

 sometimes she attacks a tree which is beginning to decay 

 from other causes. A suitable tree having been selected 

 about July, she perforates the bark, and eats away a verti- 

 cal passage about two inches in length, laying from twenty 

 to fifty eggs as she advances. Having completed her 



WOKK OF ELM-DESTEOTING BEETLE. 



