Orange. 323 



covers itself with the long, yellowish or dark brown scale which 

 may be found upon the leaves and branches of the orange. 



Treatment. The trees should be sprayed with resin washes, 

 kerosene emulsion, or whale-oil soap whenever the young insects 

 are seen. It is especially important that this should occur dur- 

 ing the three periods above mentioned, for then the greatest 

 numbers can be destroyed. The old scales cannot be penetrated 

 by any insecticide which does not injure the foliage. 



San Jose Scale (Aspidiotus perniciosus, Coinstock). Descrip- 

 tion. This scale insect is undoubtedly the most serious to fruit 

 trees of any with which the horticulturist has to deal. It is 

 .probably a native of Chili, but was imported into California, 

 and from there it has spread to the eastern states. It is now 

 very irregularly scattered throughout the East and has already 

 shown that it is capable of destroying not only the orange, but 

 also most of our other fruit trees. 



During the winter the San Jose scale is only about one-half 

 grown, the scale being less than a sixteenth of an inch in diam- 

 eter. It is nearly circular, quite flat, but the center has a slight 

 elevation. This is of a dark color, while the remainder of the 

 scale is gray. These immature forms begin sucking the juice 

 of the plant as soon as growth commences in the spring. They 

 complete their growth in about four weeks, and then lay their 

 eggs under the scale. Early in June, in the latitude of New 

 York, the young insects begin to crawl out from under the old 

 scale. In two or three days they settle down, and begin the 

 secretion of a scale which resembles that of the parent form. 

 Before fixing themselves they are active, and so minute that 

 their small yellow bodies can scarcely be seen without the aid 

 of a glass. 



From the time of the appearance of the first generation in 

 spring, the young insects can be seen almost continually through- 

 out the summer months, and until the arrival of cold weather in 

 the fall. The number of generations which appear in a season 

 has not yet been ascertained. 



Treatment. The most effectual method of ridding plants of 

 this pest is by treating them, while dormant, with hydrocyanic- 

 acid gas. With grown trees, the operation of covering an 

 entire plant with an air-tight tent is a difficult process, al- 

 though it has been done successfully in the orange groves of 



