THE RUST MITE. 119 



circling the orange, as the ecliptic does the earth. The 

 rust ring is seen most plainly on the fruit from the upper 

 portion and south side of a tree when it stands with others 

 in a grove, and will be found to mark the band of half 

 shade between the portion of the orange most directly ex- 

 posed to the sun's rays and that in densest shadow. The 

 surface covered by this penumbra band is precisely that 

 upon which the mites gather most thickly in the middle 

 of the day. Here their attacks upon the rind will be 

 most severe, and its after effects most noticeable. 



There is also observable in rusted fruit a marked differ- 

 ence in the amount of discoloration upon the opposite 

 sides. Even where no plainly marked ring is visible the 

 side of the fruit which upon the tree was turned opposite 

 the sun frequently presents a bright spot, and the opposite 

 side an area of lighter bronze, with less sharply defined 

 boundaries. 



These facts, taken in connection with the observed habits 

 of the mites, may be regarded as the strongest evidence 

 showing a connection between rust and their attacks upon 

 the fruit. 



Influence of Weather. It has been already observed that 

 the hatching of the eggs, although retarded, does not cease 

 in cold weather, and that the breeding continues throughout 

 the year. Frost, which is sometimes severe enough to kill 

 the adult mites, does no injury to the eggs, and the sever- 

 ity of a winter has little if any effect upon the prevalence 

 of the mites during the following summer. In droughts, 

 however, there is some evidence that many of the eggs 

 dry up and are exterminated. The extremely dry seasons 

 of 1881 and 1882 have been followed in the winter of 

 1882 and 1883 by the brightest crop of fruit that has 

 been known for several years. 



Agencies which Assist in the Distribution of the Mites. The 



