39 



and is now one of the worst pests the lemon grower has to deal with. 

 For a number of years the effect of its attacks in California was 

 ascribed to a fungous disease, and it was not until the writer visited the 

 lemon districts about San Diego Bay in 1896, and identified the injury 

 as due to the Florida rust mite, that its true nature was known. Our 

 knowledge of its life history and habits and the remedies for it are 

 chiefly due to the work of Mr. Hubbard in Florida. 



This mite develops on both the leaves and fruit, although its presence 

 on the former is often overlooked. On the foliage the presence of the 

 mite causes the leaves to lose their gloss and become somewhat curled, 

 as though by drought. The leaves are never killed, however, the 

 attack resulting merely in the considerable checking of the vigor of 

 the plant. 



The presence of this mite affects the fruit of the lemon slightly dif- 

 ferently from that of the orange. 

 The ripening fruit of the orange, 

 after having been attacked by the 

 mite, becomes more or less rusted 

 or brownish, and the rind is hard- 

 ened and toughened. While the 

 orange loses its brilliant fresh 

 color and gloss, the toughening 

 and hardening of the rind enables 

 the fruit to stand long shipment, 

 and protects it very materially 

 from decay. The quality of the 

 juice is rather improved by the 

 mite than otherwise, the mite- 

 attacked oranges being more juicy 

 and sweeter flavored. As a re- 

 sult of this, a demand grew up in the Northern markets for the rusty 

 fruit, and good prices were obtained for it. 



In the case of the lemon, however, an injury to the rind is an impor- 

 tant consideration, a perfect rind being a requisite of the fruit, on 

 account of the numerous uses to which the rind is put and the valuable 

 products obtained from it. The effect on the lemon is also somewhat 

 different from that on the orange. The rind of both fruits, when 

 attacked by this mite in the green stage, becomes somewhat pallid or 

 "silvered, ""due to the extraction of the oils and the drying up and 

 hardening of the outer layer of the skin. This whitening is much more 

 marked with the lemon than with the orange, and, since the lemon is 

 often picked while green, the subsequent rusting is not nearly so nota- 

 ble; hence, in California this mite is known chiefly as the silver mite. 

 If the lemon is allowed to fully ripen on the tree, however, it also 

 becomes bronzed or rusted, but rather lighter in shade than the orange. 



172 



Fig. 33.— The rust or silver mite {Phytoptus olei- 

 vorus Ashmead). a and h, dorsal and lateral 

 views of adult mite; c, leg of same; d, egg; e, 

 lemon rind showing pits normal to surface and 

 mites and eggs — all greatly enlarged, (a to d 

 copied from Hubbard; e, original.) 



