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as, in spraying large trees, a uozzle throwing a coarser spray must be 

 U3ed. It is advisable to have several interchangeable nozzles to suit 

 the different kinds of work. There should always be a detachable cap 

 to the nozzle, so that auy obstruction may be quickly and easily remov- 

 ed. Many nozzles are provided with a fine point, held back by a spring, 

 but which, when pushed forward, clears the aperture. 



A few further remarks may be quoted from Mr. Lounsbury's 

 report in which he gives some recommendations for . the care of spray 

 pumps. * Bef ore a spray pump of any kind is put away alter use, it 

 should be thoroughly washed and clear water pumped through it ; hot 

 water answers much better than cold if sticky or soapy washes have been 

 used. The working parts should be occasionally oiled, and if the paint 

 on the iron parts becomes worn away it should be renewed. Attention 

 to these details will preserve the pump for a long period, while, if they 

 are neglected, the pump may never save its initial cost.' 



Before quitting the subject of general remedial measures and en- 

 tering upjn detailed descriptions of particular processes, something 

 should be said upon the important question of the introduction of 

 ' natural enemies ' of the Coccidae. The same circumstances that make 

 an imported pest so exceptionally dangerous, act in our favour in the 

 importation of beneficial insects. Just as the absence of its established 

 natural enemies enables an insect pest to multiply without hindrance, 

 so the introduction of a beneficial insect without its own natural checks 

 will also permit of its rapid increase as long as an ample supply of 

 congenial food is obtainable. When the food supply begins to fail, 

 which means when the pest has been mastered by its imported enemies, 

 then they will both decline together. There need be little fear that, 

 when the food supply has been exhausted, the imported insect will itself 

 become a pest. A predatory insect, by which is understood one that 

 preys upon other insects or animals, will seldom, if ever, alter its diet 

 and become a vegetarian. 



It is noticeable that an insect seldom assumes any importance in 

 its original home unless through some accidental or artificial interfer 

 unce with the balance of nature in that part. (For instance, it has been 

 asserted that the wide-spread destruction of moles in England has re- 

 sulted in a marked increase of damage 10 pasture land from the grubs 

 of the ' cockchafer ' beetles and ' crane-flies, ' upon which the moles 

 fed.) Consequently, if we are to obtain any benefit from the use of 

 natural agents, we must endeavour to reproduce the conditions prevail- 

 ing in the country where the insect in question is known to occur, 

 though without attracting notice as a pest. Or, if the original home of 

 the injurious insect is unknown, we may reasonably hope for good re- 

 sults from the introduction of an insect that is found to prey upon some 

 allied pest in another country. 



The most i < portant natural enemies of the scale insects, or, at 

 least, those that have attracted most attention, belong tc a family of small 

 beetles popularly known as ' lady-birds.' The complete success attend- 

 ing the introduction of an Australian lady bird (Vedalia cardinalis) into 

 California, where it cleared the orange orchards of the destructive 

 4 Fluted-scale ' (Icerya purchasi) has led to numerous other experiments 

 of a similar kind. These experiments have not always been successful. 

 There must, of necessity be many failures. We are still only in the 



