PLANTING AND CAKE OF TREES 151 



It is well to determine also whether the insect causing the injury- 

 is in the larval or adult form. As a rule, injury is caused by in- 

 sects in the larval form only, but some species, like the Elm-leaf 

 beetle, feed during both the larval and adult stages. With insects 

 of the latter type it is always advisal)le when possible to destroy 

 them in the adult form before they have had a chance to deposit 

 their eggs, and in this way prevent the ravages of the second gen- 

 eration. 



Spraying for Insects — The most common and the most satis- 

 factory method of controlling insects is by spraying. There are 

 many instances, however, where spraying is not practicable, and 

 there are many kinds of insects that cannot be controlled in this 

 way. The preparation and application of insecticides and the ap- 

 pliances used in the work will be discussed under the heading of 

 "Insecticides, Fungicides, and Spraying." 



Hand-Piching of Insects — The large and conspicuous cater- 

 pillars often may be controlled by hand-picking. Their presence 

 usually may be indicated by their droppings on the ground. Cat- 

 erpillars that live in colonies or that build tents like the fall web- 

 worm and the tent-caterpillar, may be destroyed either by burning 

 with a torch or by cutting or brushing them out and dipping them in 

 kerosene. Conspicuous nests and Qgg masses like those of the gypsy, 

 tussock, and brown-tail moths, may be destroyed either on or off the 

 tree during the dormant season. Where small bounties have been 

 offered to school children, serious pests have been kept under con- 

 trol without further expense. 



Borers also are usually controlled by hand-picking, ^ne saw- 

 dust-like castings around the base of the tree is an indication of 

 their presence. A sharp pocket knife, with which to dig the insects 

 out, will be found useful. A flexible wire or an old-fashioned 

 knitting needle sometimes may be used to kill the insect without 

 cutting into the bark. 



Banding and Trapping — Man}^ ways have been devised for trap- 

 ping insects and thus preventing them from reaching their feed- 

 ing and breeding places. These methods of control are especially 

 useful on forest lands and other places where it is impracticable to 

 spray. Sticky bands and other obstacles tied around trees make it 

 possible to destroy many insects that congregate beneath the band 

 in their efforts to reach the foliage. This method is especially 



