34 TOWN PLANTING 



prevent the ingress of water, the decay and 

 death of not a few trees being directly attri- 

 butable to this cause. That dead and dying 

 wood will induce the attacks of injurious in- 

 sect pests, such as the goat and wood leopard 

 moth, which also attack healthy trees, is well 

 known, and was exemplified in some of our 

 London parks lately where Thorns and various 

 species of Pyrus were attacked and injured by 

 the caterpillar of the leopard moth, which 

 was bred in the adjoining old Chestnut trees. 

 The latter part of May or beginning of June 

 is perhaps the best season for pruning the 

 majority of hard-wooded trees, as during 

 that time the motion of the sap is most 

 vigorous, and, in consequence, the wounds 

 caused by amputation heal quickest. There 

 are a few exceptions the Birch, Maple, and 

 Sycamore where, on account of profuse 

 bleeding, pruning is best postponed till after 

 the leaves have developed. In cutting or 

 shortening small branches a sharp pocket- 

 knife will be found most convenient; but, 

 when large and weighty limbs have to be 



