100 INSECTS AFFECTING THE ORANGE. 



inert and harmless to man, and acts mechanically by covering and stifling 

 the Bark-lice or by removing them bodily from the tree. (See Appen- 

 dix II, table G.) 



Very many substances used separately, or in various combinations, 

 are recommended as remedies for Scale-insect. Among the number the 

 following have been examined with more or less care and found to be 

 of doubtful or of no value : sal-soda, muriate of potash, salt, lime, soot, 

 and ashes. 



Many otherwise valueless washes and applications have been ren- 

 dered partially effective by the addition of a small quantity of free kero- 

 nene. The result in all such cases has been a very unequal distribution 

 of the oil, some portions of the tree receiving a dangerous dose and 

 other portions none at all. It seems hardly necessary to point out the 

 uselessness of such half-way measures in combatting a pest which the 

 most perfect remedy is powerless to eradicate unless applied with thor- 

 oughness and care. 



THE APPLICATION OF INSECTICIDES. 



Fineness and Force of Spray. In dealing with an enemy so thor- 

 oughly protected as are many of the Bark-lice, liquid insecticides should 

 be applied in as fine a spray as possible, or at least in moderately fine 

 spray, driven with considerable force, in order to increase to the ut- 

 most their penetrating power. The aim should also be to reach and 

 thoroughly wet every portion of an infested tree, so that no individual 

 Scale-insect shall escape the action of the liquid. This result is not at- 

 tainable by the old method of sending a jet from a distance into the tops 

 of the trees. An ordinary garden syringe is practically useless. There 

 is needed a force pump and a nozzle giving a finely atomized spray. 

 This nozzle should be attached to a sufficient length of flexible hose to 

 allow it to be introduced into the top of the tree. The orifice of the 

 nozzle should be directed at a right angle to the hose, and not in line 

 with it. The jet of spray may thus by a turn of the wrist be directed 

 upward or downward, and brought into contact with all parts of the 

 foliage and branches, from beneath as well as from the upper side. 



The Cyclone Nozzle. (Fig. 44: 1, profile 5 2, plan; 3, section). A nozzle 

 which answers the above conditions and is easily attached to any force- 

 pump by means of a rubber tube is described in the report of the En- 

 tomologist (Report of the Commissioner of Agriculture for 18S1-\S2, p. 

 1 (J2). It consists of a shallow, circular, metal chamber soldered to a short 

 piece of metal tubing as an inlet. The inlet passage penetrates the wall 

 of the chamber tangentially, admitting the fluid eccentrically, and caus- 

 ing it to rotate rapidly in the chamber. The outlet consists of a very 

 small hole drilled in the exact center of one face of the chamber. The 

 orifice should not be larger than will admit the shaft of an ordinary pin. 

 Through this outlet the fluid is driven perpendicularly to the plane of 



