THE RUST MITE. 121 



Spiders of the web-making kinds are necessarily depend- 

 ent upon the wind in making long voyages. The warm 

 southeasterly winds of spring excite in them the migra- 

 torial instinct, and at a time when the orange trees are 

 swarming with the quickened life of scale and mite, from 

 a thousand projecting points of branch or leaf the spiders 

 are sending out their lines of rapid transit, and are bear- 

 ing with them, "on the wings of the wind," the seeds of 

 mischief to the orange grower. 



The Mite known only upon Plants of the Citrus Family. 

 The rust mite attacks indiscriminately the various species 

 of citrus in common cultivation, but has not been observed 

 to feed upon plants of any other genus. It is found upon 

 the lime, citron, shaddock, bigarde, and tangerine, and 

 none of the varieties of the orange are known to be in any 

 degree exempt. 



Upon the leaves and fruit of all these species of 

 citrus, the effects of its attacks are essentially the same, 

 although the rust is more noticeable on the sweet and 

 bitter orange. 



Effect of Attacks upon the Foliage. Like certain internal 

 animal parasites, which feed only upon the fat of their 

 host and do not touch its vital organs, the mite does not 

 destroy the vital functions of the leaf. The chlorophyl is 

 untouched, and the plant is robbed of a portion only of 

 its essential oil. The leaves never drop, no matter how 

 severely attacked, but there is a loss of vitality, and the 

 growth of the plant is checked. This is especially noticed 

 in young trees, which are frequently overrun by the pesta 

 in early summer, and during the remainder of the year 

 make little progress. 



The foliage of affected trees wears a dry, dusty appear- 

 ance, and loses color. The leaves are without gloss, and 

 become slightly warped as in droughts. 



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