202 REPORT OF THE DEPARTMENT OF ENTOMOLOGY OF THB 
TABLE IJ.—MorTALITY OF SAN JOSE ScaLz LARVA DURING ACTIVE PERIOD. 
Number 
: Number : Num-  Percent- 
No. Reproductive young t ure. ber age of - Remarks. 
period. produced. died. mortality. 

down. 
1 Sept.25 to Nov.1 59 52 7 1 Scale notremoved. 
bs a3 12 2 10 83 “6 é 
3 As 4 26 20 6 23 €6 KS 
4 é6 66 87 67 20 23 Be il 
5 66 6s 14 4 10 70 £cale removed. 
6 sé 6 61 34 27 44 6 ef 
Ff ‘é be 12 9 3 95 6c &é 
Average 
Motale Lowes woe 271 188 83 39 _8 
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. 
Duration—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 larvee 
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: 
