INSECTS INJURIOUS TO CITRUS GROVES. 519 



Rust mites occur in great numbers on the leaves and 

 fruit, as many as 4,568 having been found by the late 

 H. G. Hubbard on a square inch of leaf surface in winter. 

 During warm weather, when not too dry, these insects 

 multiply rapidly. 



They attack both the leaves and the fruit. When the 

 leaves are attacked they lose their glossy color and be- 

 come covered with brownish spots, but it is upon the fruit 

 that its effects are most noticeable. The mites feed upon 

 the essential oil of the rind and through the punctures 

 which they make the air comes in contact with the oil, 

 bringing about a change in color. On the lemon, the col- 

 oration is somewhat silvery, hence the name applied to 

 the insect by Mr. Marlatt. Fruit when attacked does 

 not develop normally, but remains undersized. The in- 

 sects prefer and seek the shade, hence, the under side of 

 the fruit not exposed to the sun becomes "rusty," while 

 the upper portion in the strong light is not affected. 



Because of its attacks, the cost of handling the citrus 

 crop is increased materially, as two classes of fruit have 

 to be made. As a matter of fact the russet fruit is sweeter 

 than the bright, but usually brings somewhat less money, 

 the markets generally preferring a smooth, bright fruit. 



Remedies. Spray with formula (11), (12), or 

 (13) or dust with sulphur and lime in equal parts every 

 two weeks. A more adhesive solution, formula (13), may 

 be used, if so desired, and this will destroy the scales as 

 well. If this solution is used, the intervals of applica- 

 tion may be lengthened out to about a month with fairly 

 good results. 



The Six-Spotted Mite. (Tetranychus sex-maculatus 

 Eiley). The length of full grown specimens is 0.3 mm, 

 or about .012 of an inch. This is slightly smaller than 



