A tree is a live thing, and a living organism — not merely a 

 stick of wood — and for that reason the proper trimming of a tree 

 is a surgical operation. 



Consequently the Department will not allow street trees to be 

 trimmed by individuals in front of whose properties the trees may 

 grow, but itself trims and cares for all trees in the streets of the 

 borough. 



Insect Work 



This is another of our routine activities in "caring for" the 

 trees. There are insects and insects. Some of them are harmless, 

 indeed beneficial. Others of them are the divil's own pests. Such 

 are the Tussock Moth (Caterpillar, the Elm Leaf Beetle, the Wood 

 Leopard Moth) borer, all ferocious devourers. Other pests, not so 

 destructive and covering but limited areas, are the red spider, bag 

 worm, spiny elm caterpillar, woolly louse, cottony maple scale, 

 aphis phenacocus. 



The Tussock Moth directs its ravages against a practically un- 

 limited variety of (shade) trees and shrubs. The Elm Leaf Beetle 

 confines its attacks to the Elm. These (the tussock and the beetle) 

 are leaf eaters, as distinguished from the wood-eating borer. 

 Against the tussock and the beetle we use a solution of Arsenate 

 of Lead, eight pounds of the arsenate to one hundred gallons of 

 water. This we apply in a fine spray by means of a gasoline 

 sprayer, 2y 2 horsepower, aiming the spray at the underside of the 

 leaves and taking pains to do thorough work. Spraying for leaf- 

 eaters, especially the tussock and the beetle, lasted from the latter 

 part of May to about the middle of July. 



The Borer (wood leopard moth) is a wood-eater, as we have 

 said. Also he's an imp of destruction. His presence argues at the 

 outset poor nutrition and low vitality of the trees. While the cater- 

 pillars are harmful, because of their numbers, one borer will suffice 

 to kill a stately young tree. His attack is strategic. He makes for 

 the cambium layer of cells beneath the bark and tunnels around the 

 tree horizontally. Since the ascending and descending sap has its 

 course through the cambium layer, and since the tunnels break the 

 cellular connection, the circulation of sap ceases. The borer is 

 immune from wholesale mechanical methods of extermination. 

 Each grub must be sought out individually, and often one or two 

 days will be consumed in locating them in a large tree and ridding 

 it of them. This may cost $5.00 per tree, while a tree of like size 

 may be cleared of ten thousand caterpillars with one dose of spray 

 at a cost of thirty cents. 



We have to combat several varieties of this pest, but the method 



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