Nov. 13, 19x6 
Rosy Apple Aphis 
333 
REPRODUCTION 
The migrants appear to commence reproduction in about 1 to 2 days 
after settling upon the rib grass. The period for those transferred in the 
experiments varied from 1 to 5 days. It is very probable, however, that 
those insects which required the longer period were transferred too soon 
after becoming winged, since in the field the migrants usually remain on 
the apple for one or two days at least after the last molt. 
Ten migrants produced an average of 18 young, varying from 10 to 29. 
The average reproduction period for these individuals was 5.8 days, 
varying from 3 to 9 days. The daily average was 3.2 young per female. 
It is very interesting to note that without exception the mothers brought 
forth more young on the first day of reproduction than on any of the 
following days, the numbers of young ranging, with one or two excep¬ 
tions, from 7 to 10 for that day. It will be noted later that the repro¬ 
duction of fall migrants resembles that of the spring winged form. 
longevity 
The total average length of life for the 10 insects which have just been 
mentioned was 25^ days. As stated when discussing the length of life 
of immature forms, the period spent on apple averages 12 days, plus 1 or 2 
days as adults. The average length of life on rib grass was 12% days, 
varying from 3 to 29. All but two of the insects observed lived for at 
least 2 days after producing their last young, while one lived in this way 
for 15 and another for 22 days. These conditions also will be found to 
exist in an exaggerated form among the fall migrants. 
MIGRATIONS OF THE) SPECIES 
For many years entomologists have recognized the importance in the 
life history of this species of its secondary host. The actual discovery 
of this host was first made by Theodore Pergande, although no record 
was published. It would appear that Pergande observed the aphids 
under greenhouse conditions, for his first date referring to the plantain 
is January 25, 1882. His manuscript note reads as follows: “Large 
numbers of this aphid are noticed to-day on leaves of the narrow-leaved 
plantain. * * * They are found in all stages; larva, wingless females, 
pupae and winged insects.” Several of the specimens referred to were 
mounted on slides and these have been examined by the senior writer 
and are without a doubt A. imlifoliae. 
Since Pergande published no account of his findings, it had been 
believed by entomologists that the alternate host of the species had 
never been located. This is the view set forth in all the publications 
on the species. Ross (8, p. 23), however, reported his transfers made 
to Plantago major and P. lanceolata; and since his note appeared, these 
plants have become fairly well known as the alternate hosts of the 
species. The writers’ observations on the species in connection with 
plantains were begun in 1913 when the senior writer made transfers to 
64311°—16 - 3 
