303 Report of the Department of Entomology of the 

 Table II.— Mortality of San Jose Scale Lart^ During Active Period. 



In two of the records the percentage of mortality is very high, 

 while in the remainder, with the exception of No. 6, not more 

 than 25 per ct. perished. Although all of the females and 

 young were kept under the same conditions, no reason for the 

 much higher percentage of mortality in some cases than in others 

 could be ascertained. As shown by the table the average mor- 

 tality was almost 40 per ct., leaving about 60 per ct. that 

 lived to settle down. The comparatively small number produced 

 by each female is noticeable, but it is not exceptional to our 

 experience with a large number of other females of the fall 

 broods kept under observation. It is not improbable that 

 females of the late broods give birth to fewer young than those 

 of earlier broods. 



PERIOD OF GROWTH. 



But-^tion. — The period of growth lasts approximately from 

 the time the larva settles down until the beginning of the repro- 

 ductive period. In the field there is much variation in the dura- 

 tion of this period. In the laboratory and insectary there was 

 also much variation, especially in the case of 19 of the larvae 

 under observation. Fifteen of these were transferred to smooth- 

 skinned apples and kept in the insectary and four were placed 

 on the smooth bark of a young apple tree also in the insectary. 

 The results are shown in the following table; 



