PBESEIN^T STATUS OF THE PROBLEM. 9 



practical manner, and who consequently get the best results. It is 

 now largel}" a matter of getting the owners of small orchards to 

 follow a regular annual system of spraying their trees. 



The presence of San Jose scale has not only resulted in a consider- 

 able increase of information as to remedies and to improvements in 

 the methods of culture which directly relate to itself, but it has been 

 a stimulus to improved methods and more efficient means of control 

 of other common destructive insects, has demonstrated the necessity 

 of watchfulness against the introduction of similar pests from foreign 

 sources, and has led to active efforts in the direction of quarantine 

 and inspection on the part of practically all of the several States of 

 the Union. 



The control of the San Jose scale by parasitic and predaceous ene- 

 mies is increasing all the time, but there seems to be no likelihood that 

 either such natural enemies as are now in this country' or those which 

 ma}^ hereafter be imported will ever do more than merely lessen the 

 abundance of the scale. In other words, from past experience and 

 from a large acquaintance with other similar scale pests it is extremely 

 improbable that even under the most favorable circumstances will such 

 natural enemies reduce this scale as much as would one thoro treatment 

 with the lime-sulfur wash or other standard remedy. The insect 

 enemy of the scale can only exist when it has scale food; hence a nor- 

 mal balance is very soon reached in which the scale and natural enemy 

 fluctuate in relative abundance. A complete extermination of the 

 scale insect or host will rarely if ever be accomplished, and there will 

 probabl}^ alwaj^s be enough scale present to cause spotted and unmark- 

 etable fruit. This does not mean that such enemies are not going to 

 be helpful. The}'^ will decrease the virulence and destructiveness of 

 the scale, but to get clean fruit it will probably be always necessary 

 to spray. A very few scale on a tree will cause spotted fruit even 

 when they may not be abundant enough to do the tree itself material 

 injury. The fact that a large, succulent scale insect like the fluted 

 scale of California has been controlled by a ladybird enemy does not 

 necessarily allow one to hope for the same result with the San Jose 

 scale. The ladybird and other enemies introduced into California to 

 control scales similar to the San Jose scale have not succeeded in the 

 same measure at all. This statement is made to correct hopes which 

 may be aroused by certain popular articles which have recently 

 appeared on the subject of parasites. 



In brief, therefore, the San Jose scale must be recognized as a per- 

 manent condition to be met in the growth of deciduous fruits. The 

 greatest care should always be taken in the purchase of nursery stock 

 to see that it is absolutely free from infestation, and preferably also 

 that it carries with it a certificate of fumigation. Orchards should be 

 sprayed according to well-established methods annually as soon as the 



