230 THE ELM. 



task, she dies. About two months afterwards the eggs 

 are hatched, and the grubs immediately begin to eat their 

 way also through the inner bark in a horizontal direction, 

 some to the right and some to the left, but never inter- 

 fering with each other's track. When each grub has 

 finished its course of eating, it turns to a pupa and then 

 to a beetle ; after which it gnaws a straight hole through 

 the bark, and comes out about the end of May in the 

 year following that in which the eggs were deposited. 

 The injury thus inflicted by the grubs is so much greater 

 than that occasioned by the perfect insect, that, when the 

 former have commenced their ravages, the tree cannot be 

 saved from destruction, and the only alternative is to cut 



SPOTTED ELM-LEAF. 



it down and to burn every particle of bark. But when a 

 tree is attacked by the perfect insect, it may be saved by 

 being carefully brushed over with coal-tar, the smell of 

 which is so offensive that the insects will desert it, and in 

 the course of a few years it may recover its healthy con- 

 dition. Had this discovery been made and acted upon at 

 an earlier period, it is probable that an immense number 

 of trees in the promenades of several of the principal cities 

 of Europe, including from twenty to thirty in St. James's 

 Park, might have been saved. 



