88 INSECTS AFFECTING THE ORANGE. 



the migrating young of Bark-lice, so that if they effect a lodgment upon 

 any plant, the entire row, and even the whole nursery, is quickly over- 

 run by them. 



The crowding of the plants prevents free and vigorous growth ; they 

 are stunted, and for want of nourishment, as well as lack of light and 

 air, they are thrown into a condition in which they are particularly liable 

 to the attack of Scale insect. In common parlance, "they breed scale." 



In the existing almost universal distribution of the pest, those nurser- 

 ies only can be kept from becoming foul in which a reasonable amount 

 of space is allowed to each plant for its growth and cultivation. At 

 least 18 inches should intervene between the plants, and the rows should 

 be not less than 3 feet apart. Experience teaches that it is easier to 

 keep clean and uninfested a large, well-ordered nursery than it is to 

 remove the Scale-insect from a single orange tree of moderate size when 

 once the pest has become fully established. 



No part of the grove is so liable to suffer neglect as the nursery, and 

 it is unfortunately a very common practice to allow seedling' plants to 

 grow up without attention in neglected corners, and frequently to become 

 so foul with scale as to become a source of infection to the groves and 

 nurseries in the vicinity. 



To this neglect, undoubtedly, is due the fact that the advance of insect 

 pests has fully kept pace with that of the orange industry in the recently 

 occupied districts, both in Florida and California. 



Protection afforded by Hedges and Forest Trees. It is a serious evil, and 

 one as yet hardly appreciated, that in Florida, in removing the forest 

 to make way for the advancing orange groves, every tree is generally 

 sacrificed. Not even in the lanes and roadways has the ax spared an 

 occasional pine to serve as a wind-break against the sweep of storms. 

 In many districts, once well clothed with timber, the naked laud for many 

 miles now lies exposed to the destructive force of gales, which, by whip- 

 ping and thoruiug the fruit, will, when the groves begin to bear, occasion 

 severe losses. 



The pines of the original forest, from their great height, serve to break 

 the force of upper currents, and a single giant tree extends its protecting 

 influence over a wide area. If cut, the loss is well-nigh irreparable ; many 

 generations must elapse before its place can be satisfactorily supplied 

 by the lower and more spreading oaks and pines of second growth. But 

 a discussion of this subject, though of sufficient importance to horticul- 

 turists, would be out of place in the present treatise, were it not for the 

 great value of wind-breaks as an aid in isolating and preventing the 

 spread 6f Scale-insects and other pests of fruit-trees. 



From the time of their first appearance it has been remarked that 

 Scale insects spread most rapidly in the direction of prevailing winds. 

 This phenomenon is now known to be due to the influence of the wind 

 in guiding the flight of other insects which transport the minute, crawl- 

 ing young of Bark-lice upon their bodies. 



