ENTOMOLOGY 121 



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 rem- 

 edies 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 pres- 

 ence of the mite causes the leaves to lose their gloss and become some- 

 what curled, as though by drought. The leaves are never killed, how- 

 ever, 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 

 differently 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 hardened 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 result 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 

 important 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 pal- 

 lid 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 notable ; 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. 



As in the case of the orange, the rind of the lemon is hardened 

 and toughened, but the juicy contents are not affected materially; 

 furthermore, a silvered lemon will keep very much longer than a 

 perfect lemon, and will bear long shipment without risk of much 

 loss. Until very recently the rusted lemon in southern California 

 found no market whatever, and was a total loss to the grower. The 

 scantiness of the crop in 1900 resulted, however, in some shipments 

 of rusty fruit being made under the name of russet lemons, about 

 half the normal price being obtained. Should the manufacture of 

 citric acid assume very much importance in southern California, the 

 mite-injured lemons could be used for this purpose. Nevertheless, 

 considering the ease with which the mite may be controlled, there is 

 no excuse for allowing it to maintain itself in injurious numbers in a 

 lemon grove, since, irrespective of the appearance and value of the 

 fruit, its work on the foliage materially lessens the healthfulness and 

 vigor of the plant. 



