THE RUST MITE. 113 



to attacks of the mites, but it is in the intermediate period 

 of its growth that the fruit offers conditions most favorable 

 to their increase. 



Attacks of the Mite always followed by Rust. The evidence 

 that rust follows as a sequence upon the depredations of 

 this mite is circumstantial rather than direct, but is also 

 cumulative. Oranges marked and kept under observation, 

 but allowed to remain upon the tree, have in all cases 

 rusted after being overrun by the mites. Those upon 

 which no mites made their appearance remained bright to 

 maturity. 



A very large number of observations show a close con- 

 nection between the occurrence of mites upon the foliage 

 and rust on the fruit, so that it may be stated as a rule, 

 when the foliage of a tree retains its gloss, the fruit also 

 will be bright, and, conversely, when the condition of the 

 leaves indicates the presence of mites in great numbers, 

 the fruit will be discolored. 



This is found to be true, not only of the entire tree but 

 of restricted portions. Thus the upper, the lower branches, 

 or one side of an orange tree may produce rusty fruit while 

 that on the other parts of the tree remains bright. In 

 such cases there will always be a marked difference in the 

 condition of the foliage upon the two portions, and the 

 leaves surrounding the affected fruit will indicate more or 

 less clearly the work of mites. 



Other and perhaps more exclusive reasons for consider- 

 ing the mite responsible for rust will be better understood 

 when the habits of the mite itself have been considered. 



Interval between tJie Disappearance of the Mites and the 

 Appearance of Rust. As has been indicated, the mites do 

 not permanently infest either the surface of the leaf or the 

 rind of the fruit, but wander off to fresh feeding ground 

 when, through their combined attacks, all the accessible 



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