12 The Bulletin. 



These large full-grown round scales are always females, and a picture 

 of an adult female insect of the San Jose Scale, without her scale, is 

 shown greatly enlarged in Fig. 5. Press the body with the point of 

 the knife or pin and it is easily crushed, yielding a tiny bit of yel- 

 lowish, oily liquid. 



If you rub the flat of the knife-blade along the thickly-infested 

 branch the insects will be crushed in such numbers that the oil from 

 their bodies becomes quite noticeable, though of course not enough to 

 run down the limb. 



DIFFERENT AGES AND STAGES OF GROWTH. 



In Fig. 3, note in the enlarged picture, that in the extreme lower 

 right-hand corner there is a scale which is oblong in shape rather than 

 rounded. Two other similar scales are seen near the left border of 

 the figure, about an inch from the top. These are male scales, and 

 may be readily disting-uished from the female scales, which are 

 nearly circular. The very large circular scales ' are of full-grown 

 females, and these at largest are about the size of a pin-head, so you 

 can see by comparison that the partly-grown scales are quite small. 

 Females are usually much more abundant than the males. 



Xow look at Fig. 3 again. On the right-hand border, about an 

 inch from the top, notice an insect which has legs. This is a young 

 scale-insect which has a few hours' liberty after birth before it begins 

 to feed. At this stage it can crawl about. Several of these young 

 insects are to be seen in the figiire, especially near the top. These 

 young insects when in this active crawling stage are so very small as 

 to be barely visible to the unaided eye, and are yellow in color. After 

 the young- insect has crawled about for an hour or so it becomes hun- 

 gry and inserts its delicate slender beak or sucking-tube (see Fig. 5 

 for sucking-tube of grown insect) into the tender bark and begins to 

 suck the sap. This slender sucking-tube is really the insect's mouth 

 just as the trunk of an elephant is his nose. Once the insect inserts 

 its tiny beak into the bark and begins to feed on the sap the scale 

 begins to be formed over the body. The scale is begun by the secre- 

 tion of a waxy substance from the back of the young insect, and 

 this is added to later by shedding the skin from time to time. At 

 first the newly-formed scale is white and oblong, of the same shape 

 as the body of the young insect as shown at the top in the center of 

 Fig. 3. Then the scale becomes more rounded, and as it grows it 

 becomes darker, until it is dark-gray or almost black — when fully 

 grown the scale begins to fade in color. 



We have already described the full-grown scales; now let us con- 

 sider the full-grown insects, for it must be remembered that the body 

 of the insect itself is not the same as the scale, but is concealed under 

 and is separate from the scale, or at most only slightly attached to it. 



