112 INSECTS AFFECTING THE ORANGE. 



to be wafted by the winds and caught in distant trees, has often been 

 noted. There is little doubt that of all other modes of dissemination, 

 both of Scale-insect and Enst mite, that of transportation by spiders is 

 the most important, the most constant, and regular. The spiders bear 

 with them upon their hairy bodies the young Bark-lice and the adult 

 Mites, conveying them in their own migrations to distant points, and 

 colonizing them under their protecting web whenever they chance to 

 select the leaves of a citrus plant as their resting place. 



And here is found the solution of that puzzling influence of the wind 

 so often remarked in the case of Scale-insects, and which has led many 

 to believe that they are disseminated directly by this agency, and there- 

 fore spread most rapidly in the direction of the prevailing currents. 



Spiders of the web-making kinds are necessarily dependent upon the 

 wind in making long v'oyages. The warm southeasterly winds of spring- 

 excite in them the migratory 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 bearing with them "on the wings 

 of the wind" the seeds of mischief to the orange- grower. 



RAVAGES OF THE RUST-MITE. 



The Mite known only upon Plants of the Citrus Family. — The Eust-mite 

 attacks indiscriminately the various species of Citrus in common culti- 

 vation, but has not been observed to feed upon plants of any other ge- 

 nus. It is found upon the Lime, Lemon, 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 attack are essentially the same, although the rust is most noticeable 

 on the Sweet and Bitter Orange. 



Effect of Attacks upon the Foliage. — Like certain internal animal para- 

 sites which feed only upon the fat of their hosts, 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 at- 

 tacked, but there is loss of vitality, and the growth of the plant is 

 checked. This is especially noticed in young trees, which are frequently 

 overrun by the pest in early summer, and during the remainder of the 

 year make little progress. 



The foliage of affected trees wears a dry, dusty appearance, and loses 

 color. The leaves are without gloss, and become slightly warped, as in 

 droughts. 



Rusted Fruit. — If severely attacked by rust before it has completed 

 its growth, the orange does not attain its full size. Very rusty fruit is 

 always small. Its quality is, however, improved rather than deterio- 

 rated . The toughened rind preserves it from injury and decay , prevents 



