ENTOMOLOGY 35 



ous little scales of varying sizes, beneath which lies the small, oval, 

 orange colored, jelly-like objects which are the true insects. 



If an adult female insect is closely examined, a small grayish 

 circular scale about one-twenty-fourth of an inch in diameter, the 

 center of which is convex forming a slight nipple will be seen ; also 

 numerous concentric circles can be seen around the nipple the scale 

 developing by additions to the outer edge. The scale of the male is 

 somewhat elongated. Beneath the scale is the true jelly-like individ- 

 ual. The color of the scale is variable. In the half mature insect 

 the scale is nearly black with a central gray nipple and one or two 

 grayish rings, but it gradually becomes entirely grayish when ap- 

 proaching the adult state. 



The San Jose scale passes the winter in an immature condition 

 fixed to the bark of the host plant, the small, dark-gray or blackish 

 scales being just discernible with the unaided eye. As has been 

 already stated the San Jose scale, in the absence of proper treatment, 

 will quickly bring about the death of most plants of economic im- 

 portance. When safety, cost and efficiency are all considered, we 

 believe lime-sulphur is the best remedy for the orchardist to use. It 

 can be used very liberally with little or no danger to the trees and, 

 by its color, indicates within a few hours whether the spraying was 

 thoroughly done. 



No particular difference has been observed in the effectiveness 

 of the lime-sulphur wash, whether applied in the fall or early spring, 

 during the dormant season. It is believed, however, that early spring 

 is the best time to spray, as the mixture will remain on the trees for 

 a longer period during the summer, when the scale is breeding, and 

 this is desirable. Certain manufacturers have put on the market 

 concentrated solutions of lime-sulphur wash, which have only to be 

 diluted with water for use. These commercial washes have proved 

 to be about as effective in controlling the scale as the well-cooked 

 lime-sulphur wash, and, although somewhat more expensive, have 

 been adopted by many commercial orchardists in preference to the 

 home-prepared spray. (Pop. Ed. Bui. 193 and 194, N. Y. Agr. 

 Exp. Sta. ; Bui. 148, Md. Exp. Sta. ; Cir. 129, B. of E., U. S. Dept. 

 Agr. ; Cir. 64, Ohio Agr. Exp. Sta. ; Press Bui. 48, Col. Agr. E. S.) 

 The Oyster Shell Scale.* This insect has received the common 

 name "oyster-shell scale," owing to the resemblance of its scale or 

 covering to a long, narrow oyster shell. The adult female scales are 

 about one-eighth of an inch in length, usually brown to dark brown 

 in color, though occasionally they have a grayish appearance which 

 is due to bleaching over winter. On account of its size, the scale 

 is not conspicuous unless in large numbers. The scale adheres very 

 closely to the bark of the tree, and resembles it very much in color. 

 During the winter, it shelters the eggs. 



A cheap and very satisfactory remedy for the oyster-shell bark- 

 louse is kerosene emulsion, applied shortly after the emergence of 

 the young. This is about May 1st for latitude corresponding to 

 Washington, D. C. 



* See illustration on page 375. 



