54 INSECTS AFFECTING VEGETATION 



with the San Jose Scale. This scale insect can be most easily identi- 

 fied during its hibernating winter stage. The scale is hemispherical 

 in form and at this time is about 2 mm. in length and slightly less in 

 width, mottled brown, with radiating streaks of black toward the 

 sides, and an orange red patch on the top, the sides being more or less 

 ridged. Sometimes individuals will be observed to be entirely red or 

 black. As the females develop in spring, the size increases and at 

 full growth the scale is about 3 mm. in length and of nearly uniform 

 reddish brown color. The eggs hatch about June 1 and the Iarva3 im- 

 mediately crawl to the leaves, usually on the under side. They re- 

 main here for a period of two months, then return to the twigs to 

 winter. 



From the above results we recommend that a standard miscible 

 oil be employed at a strength of 1 to 15, applied on the trees just as 

 late in the spring as possible before the buds open. In cases of slight 

 infestation, where only a few trees are affected, it is best to seek out 

 all such trees and treat them with an oil at the rate of 1 to 15. Inas- 

 much as such an inspection may not discover all cases of infestation, 

 it would seem advantageous to spray the balance of the trees with the 

 same mixture diluted at 1 to 20. This dilution will reduce the possi- 

 bility of the spread of the scale as well as the likelihood of any in- 

 jury to buds or twigs from oil. (Bui. 235, N. J. Exp. Sta. : Bui. 

 149, Md. Exp. Sta.; Cir. 88, B. of E. U. S. Dept. of Agr.) 



The Peach-Tree Borer.*' In the form in which it is most famil- 

 iar to the grower, the peach-tree borer is a white, grub-like cater- 

 pillar with a yellowish or brownish shield-like head, which lives and 

 feeds in the tree trunks at or just below the surface of the ground 

 and makes irregular galleries or chambers just beneath the bark> 

 from which gum and sap ooze out to form conspicuous masses. 

 These borers may be found at almost all periods during the summer, 

 but are usually very small in late summer or fall and become an 

 inch to an inch and a half in length in early summer. 



The parents of this borer belong to the Sesiid or clear-wing 

 moths. The male is a shining, slender, steel blue, wasp-like crea- 

 ture with two pairs of transparent wings marked with black and yel- 

 low scales, and the abdomen is narrowly banded with yellow. It 

 expands about an inch when the wings are fully spread. The fe- 

 male is decidedly larger and stouter, deep blue except for a broad 

 orange band around the middle of the abdomen, the hind wings 

 only transparent. The larvse feed all summer and during the win- 

 ter lie dormant doing no feeding but begin to do so with the rise 

 of sap. 



Trees of all ages may be and are infested by borers, from the 

 seedlings in the nursery to the venerable old relics still to be found 

 in some gardens. In nursery trees and in small trees generally, a 

 single larva may completely girdle and kill a tree. The work is 

 usually done just below the surface of the ground. There is no in- 

 secticide application thus far known that can be relied upon to kill 

 borers once in the trees. 



See page 285. 



