252 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
Experiments with Apple Root Forms 
Experiments were begun with a view of working out the duration 
of the instars, number of young per female, longevity, number of 
generations per season, etc., of the apple root forms. We got satis¬ 
factory results by using tin salve boxes in the bottom of which we 
poured paraffin mixed with lamp black. This enabled us to detect 
aphids or exuviae which had fallen on the bottom of the box. Pieces 
of root were wrapped at one end with moist cotton batting and the 
other end was left exposed for the aphids. The boxes were sunk in 
soil out of doors and were covered with a board. 
Records of 40 aphids made by my predecessor, Mr. Paul Hayhurst, 
during March and April of 1910 are summarized in Table VI. 
The days for each instar are given. Duration of the fifth instar is 
practically the same as the period of reproduction as aphids almost 
invariably begin to reproduce on the same day that they moult the 
fourth time. The number of days from birth to the first young will 
therefore generally be the same as the combined number of days of the 
first four instars. The age at death is expressed in days. 
Table VI 
Days 1st 
Instar 
Days 2nd 
Instar 
Days 3rd 
Instar 
Days 4th 
Instar 
Days 5 th 
Instar 
Days to 
Young 
Max. Yng. 
per Day 
Total 
Young 
Age at 
Death 
Average. 
7.3 
3.9 
3.2 
3.8 
22.6 
18.8 
11.5 
86.3 
40.2 
Range. 
...3-14 
2-7 
1-6 
1-8 
5-47 
15-25 
2-23 
8-167 
21-59 
If the aphids develop on the roots of apple under normal conditions 
as well as in the salve boxes and if later generations develop as rapidly 
as the generations in March and April, it would appear that it would be 
possible for 6 to 12 generations to develop from March to November, 
which period is the period of activity of the root forms in this latitude. 
Experiments with Fall Migrants 
In 1915, 1916 and 1917 we made numerous attempts to get fall 
migrants to deposit sexuparise on Crataegus, apple and elm seedlings 
under cage conditions. Migrants were placed in cages of varying 
sizes with these seedlings and with large limbs from elms but we failed 
to get the sexed forms in 1915 and 1916. During the same period we 
also tried placing seedlings of its three hosts in the window and releasing 
the migrants in a dark corner of the laboratory. Although the mi¬ 
grants made their way to the seedlings they failed to deposit young 
on them. In 1917 we succeeded in getting migrants to deposit the 
sexed forms by confining them in large vials and under glass cylinders 
with rough pieces of elm bark, however, we failed to get any eggs 
from the sexed forms, 
