No. 4.] ORCHARD SCALES. 357 



Jersey. An investigation in the latter State led to the dis- 

 covery that two nurseries there had about the } r ear 188(5 or 

 1887 introduced the " Kelsey " plum from California, in the 

 hope that it might be proof against the attacks of the cur- 

 culio. The trees thus obtained did not thrive (probably 

 because the} r were infested by this scale) , and were ulti- 

 mately destroyed, but presumably not until the insect had 

 spread from them to other nursery stock. As both of these 

 nurseries did a large business, the scale was in this way 

 scattered all over the eastern and middle States before the 

 danger was realized. As many of the places to which the 

 infested stock was sent were nurseries, these in turn became 

 infested, with the result that the San Jose scale is now 

 present in nearly every one of the United States, as well as 

 in Canada and other foreign countries. 



Life History. 



The insect passes the winter under the scale, but it is 

 probable that both the adult and the very young insects die 

 during this period. In the spring those which are alive re- 

 sume their feeding and become full grown about the first or 

 middle of June. The production of }'oung soon follows, 

 these being born alive. When the }■ oung first appear they 

 are extremefy minute, yellowish in color, and with six legs. 

 They crawl away from the parent scale and move about for 

 a day or two, then settle down, and, inserting their beaks 

 into the bark, begin to suck the sap from the tree. About 

 this time little waxy threads develop on the surface of the 

 body, and soon fuse together to form the first portion of the 

 covering scale. When this is completed, the scale is white, 

 nearly circular in outline, and with a little hump or nipple 

 in the centre. About ten days later the insect molts its 

 outer shell and adds this to the covering scale, which by this 

 time has become dark gray, except the central nipple, which 

 is lighter colored, often yellow. About ten days later the 

 female insect molts again, and, as before, adds the molted 

 skin to the covering scale, thus making it larger than those 

 of the males, which do not undergo a second molt. 



Soon after molting the second time the females become 



