372 A PRACTICAL HAND BOOK 



one-third to two-thirds grown to reach the adult condition in the 

 spring. This is accomplished by the latter part of May or early 

 June, and then the young appear, one or two every few days for a 

 month or more. These young, which are born alive, are very tiny, 

 lemon-yellow insects which escape from beneath the scale of the 

 parent and crawl about for a day or two. Each has a long beak 

 through which to suck the sap frc/m the plant, and on finding sat- 

 isfactory places the young settle down, force their beaks through 

 the bark and begin to feed. White waxy threads now grow out of 

 their backs and mat together, forming very small white specks as 

 the first coverings of the insects. To these are added molted skins 

 from the insects beneath, turning the scales brown or gray, and 

 enlarging them, and thus the scale covering the adult insect is 

 gradually formed. 



The young become adult in about a month, and then they them- 

 selves produce young and there are three or four generations, 

 according to the length of the season, before winter ends this pro- 

 cess. During the summer enormous numbers of the insects 

 are produced in this way. If all the young born survived, and 

 themselves produced the normal number of young in each genera- 

 tion, it would be possible for the descendants of one female to 

 number over three billions in a single season. Fortunately, death 

 reduces this number greatly, but enough remain of ten to seriously 

 injure or even kill the plant they are on, by removing the greater 

 part of the sap from it, and thus drying it up. 



This pest is very difficult to control, first, because being a suck- 

 ing insect it must be actually hit by a contact poison sprayed onto 

 it; second, because of its small size, which renders it very difficult 

 to reach all of the individuals by spraying, and finally, because of 

 the shell or scale which covers it, protecting it from the spray. 

 For this reason very strong materials must be used, in order 

 either to penetrate or work under the scale, and these are hardly safe 

 to apply while the plant is growing. Spraying for this pest must 

 accordingly be done during the period after the leaves drop in the 

 fall and before the buds open in the spring. The lime-sulphur 

 wash and miscible (often wrongly called " soluble ") oils are the 

 most usual sprays to use for the purpose. These materials are on 

 the market under various trade names, and only need dilution 



