694 : Rospert MATHESON. 
experimentally. The period of reproductive activity varies considerably, 
as well as the total number of young produced. This is well shown in the 
accompanying chart (Reproduction Chart I) illustrating the productive 
period and the daily rate of reproduction. On examination of the chart 
it may be seen that for five stem mothers the reproductive period varies 
from 29 to 34 days, the average daily rate of production varying from 
1.38 to 2.41. The total number of young produced varied from 40 to 77. 
The greatest number of young produced by any one individual during 
a period of twenty-four hours was 10, in the case of stem mother 129. 
The total length of life from the time of hatching until normal death 
occurred varied but little, being only from 47 to 55 days in the case of 
the five insects reared under such conditions as to produce the normal 
life cycle. 
From an examination of the chart it may be observed that the period 
of reproductive activity extends from the beginning of the blossoming 
period almost up to the beginning of the ordinary June drop for apples. 
Description of stages 
First instar (Plate. XVIII).— Length 0.56-0.64 mm.; width 0.28- 
0.30 mm. 
The newly hatched nymphs are dark green, the legs and the antennae 
being dark yellowish green. The eyes and the cornicles are black. On the 
dorsal aspect of the head are two dark chitinized areas, one on each side 
of the median line. The antennae are 4-jointed, with sensoria present 
at the distal end of the third joint and at the proximal end of the flagellum 
of the fourth joint. 
At this stage the legs and the antennae are long as compared with the 
size of the body, and this gives the young lice a sprawling appearance. 
This stage grows very considerably before molting, becoming elongate- 
ovai and measuring over 0.72 mm. in length. 
Second instar.— Length 0.96-1.04 mm.; width 0.48-0.50 mm. ° 
The nymph in this stage is yellowish green, never bright nor grass- 
green in color. The cornicles and the cauda are black, the legs and the 
distal half of the antennae dusky. There are two prominent dusky patches 
on the head, one on each side of the median line. The antennae are 
5-jointed.. The cornicles are cylindrical, slightly tapering toward their 
tips, 0.04 mm, in length. 
