974 
Journal of Agricultural Research 
Vol. V, No. 21 
numbers were brought forth. Some insects bore numerous young daily 
till death; with others the production decreased gradually to that point; 
while in a third class the insects lived from 3 to 44 days after reproduction 
ceased, the longer period occurring in the fall, October and November. 
During the summer the longest period was 13 days. In one remarkable 
case an insect born on September 29 produced 10 young in 13 days (Octo¬ 
ber 13 to 26). It then ceased to reproduce till December 5 (40 days), 
when it bore one young and died. 
longevity 
The average total length of life for the entire season was 30.9 days. 
This average is only for insects which reached maturity. Many died 
while still nymphs. The greatest length of life attained by one insect 
during the summer was 48 days. In the fall the average period was 
longer than in the summer, and one insect lived 68 days. 
Wingless viviparous females were present on the trees until within less 
than a week from the time of the last appearance of oviparous females— 
i. e., during the fall of 1914 until after November 20. In the cages one 
insect was alive on December 22. 
hardiness 
A rather interesting note was made during the fall on the effect of low 
temperature on the activities of this species. On December 22 an exami¬ 
nation of about 50 insects, including wingless viviparous females and 
oviparous females, showed all the insects to be perfectly motionless, 
except one viviparous female. This insect moved both legs and antennae 
when irritated slightly with a camel’s-hair brush. The temperature at 
the time the observations were made was 34 0 F. and had remained con¬ 
stant for about 2 hours. For the 12 hours previous the temperature 
had been 30° F. or less. This would indicate that at least in individual 
cases the developmental or physiological zero for this species is quite low. 
WINGED VIVIPAROUS FEMAEE (PE. EXVII, PIG. i) 
DESCRIPTION 
First, second, and third instars. —In the first and second instars these insects 
are identical in form with those producing wingless adults. In the third instar the 
measurements are the same for those given under third instar wingless female, but 
beginnings of wing pads are present. 
Fourth instar (pupa) (pl. lxvii, pig. 3). —The pupae producing intermediates and 
those producing winged forms are identical, as follows: 
Morphological characters: Antennae as follows: I, 0.06 mm.; II, 0.06 mm.; Ill, 0.176 
to 0.256 mm.; IV, 0.128 to 0.176 mm.; V, 0.128 mm.; VI, base 0.80 to 0.112 mm., unguis 
0.216 to 0.28 mm.; sensoria, imbrications, etc., as in the wingless form. Vertex 
rounded, with a slight median indentation. Eyes prominent, with a large number of 
facets; ocular tubercles distinct and with usually three lenses. Thoracic and abdom- 
