114 THE REPOKT OF THE N^o. 36 



Geneiial Methods of Control. 



The chief injurious insects included here may be grouped as defoliating in- 

 sects, sucking insects, and borers in the bark and wood. 



Most leaf-eating insects may be controlled readily enough by the ordinary 

 poison sprays of paris green or lead arsenate. A'ery strong mixtures are at times 

 required, and it is sometimes advisable to employ a spray of strong contact in- 

 secticide as a more rapid control for hordes of caterpillars. Very young Tent 

 Caterpillars, where in immense numtoers, are best controlled in this way. 



Sucking insects are controlled by spraying with strong contact insecticides, 

 such as kerosene emulsion, fish-oil soap, and good tobacco extracts. 



The spraying of shade-trees requires the insecticides and, in general, the 

 methods employed in the spraying of orchard trees ; except that we have to reach 

 greater heights, and in such cases need a more powerful apparatus. For spraying 

 the lower foliage the ordinary nozzles and equipment are used; but to reach the 

 top of the higher trees it is necessary to employ a solid stream and a power-sprayer 

 of large capacity. A few of the power spray-pumps sold for orchard work will 

 maintain a solid stream for 60 feet from the nozzle; other pumps, excellent for 

 general work in the orchard, have a small pump capacity, and are unable to main- 

 tain a solid stream above 40 ft. By using a good " solid stream " nozzle, such as 

 the Worthley, and elevating the nozzle on a platform or ladder, the average orchard 

 power-sprayer can be made fairly effective for shade-tree work. For to-\vns and 

 cities where large numbers of tall trees are to be sprayed a special power-sprayer 

 for shade-tree purposes should be obtained. Such pumps are now available, cap- 

 able of maintaining a solid stream from 80 to 100 feet up from the nozzle. 



Spraying for shade-tree insects should be thorough. A mist spray at high 

 pressure should be employed for as high as the extension will reach; and for the 

 higher portions the solid stream is necessary. The latter uses the spray mixtures 

 very rapidly and should be employed with discretion. It is, of course, quite 

 necessary to understand the habits of the insects to be controlled and to make the 

 sprays at the proper time. 



Hand-piclcing is effective to a very limited extent. The tents of the American 

 Tent Caterpillar can be removed by means of tree-trimmers or torches; egg-masses 

 of the tent-caterpillars and the tussock moths can be removed by hand~at time? 

 with profit; and the larger caterpillars, which rarely occur in great numbers, can 

 sometimes be removed from low foliage by hand more cheaply and effectively tlmii 

 in any other way. 



The Destruction of Larger Borers: When living trees become infested with 

 large boring grubs or caterpillars it is necessary to kill the borers within the wood 

 with the least possible injury to the trees. When the borers are near the surfac-e 

 it is often possible to cut them out with a knife or chisel without mucli injury to 

 the wood ; or a wire thrust into .the borings can sometimes be used effectively. It 

 is usually possible to kill the grubs by injecting carbon bisulphide or benzine into 

 the openings. The fluid should be injected with a syringe or oiling can, and the 

 opening should be immediately closed with soap or putty. After several hours the 

 plug should be removed and the grubs extracted if easily reached, decaying wood 

 cut away, and the holes thoroughly syringed with strong lime sulphur or copper 

 sulphate, or with a solution of bichloride of mercury, and finally filled with cement 

 or putty. The fluid should be injected into the flatter holes from which sap and 

 borings have been oozing, and which evidently lead to the tunnels of living larvae. 



