5i8 
Journal of Agricultural Research voi. xxvn, no. 7 
By October 6, the oviparous females were not present on the plants 
kept under the long-day conditions, although they were already present 
on the control plant. Examined December 3, the viviparous forms were 
still present out of doors on the strawberry plants receiving the long 
daily exposure. 
INFLUENCE OF THE SHORT DAY ON MIGRATION 
Aphis rumicis L —Having been successful in securing the sex forms by 
the use of a short day, and noting that in the migrations of plant lice sum¬ 
mer is the time for dispersal to the secondary hosts, and that the return 
migrants make their appearance during the short days of the fall, the 
writer started a series of experiments to prove, if possible, that the 
migration of aphids is also influenced by the length of day. Several 
well-known migratory aphids were selected, such as A. rumicis , Capito- 
phorous hippophaes, and A. sorbi. 
In Tennessee the common snowball (Viburnum opulous) is the primary 
host of A. rumicis , and several weeds such as burdock (.Arctium lappa) and 
curled dock (Rumex crispus) serve as the secondary, or summer, hosts. 
The eggs began hatching on March 9, 1923, and small potted snow¬ 
balls bearing A. rumicis were subjected to jjJ hours of daylight. The 
stem-mothers became full-grown April 2, while pupae made their appear¬ 
ance on April 16. These became winged on April 17, and represented 
the spring migrants. In this case, as with other species, the length of 
day is apparently not operative when certain stages are predetermined, 
and follow in quick succession. Most of the second generation, under 
normal conditions, become winged and migrate, and the production of 
migrants can not be stopped in so short a time. 
On April 17 spring migrants were placed on curled dock (Rumex cris¬ 
pus), which was placed in the dark chamber and given about 7X hours 
of light. The first males and sexuparae made their appearance on June 
6 . The sexuparae were then placed on snowball, where the oviparous 
females became mature June 20, at the hottest time of the year, and when 
the days are longest. In 1922, under natural conditions, the males, 
females, and sexuparae were present on snowball October 19. 
Capitopkorous hippophoes Koch.—This species, as determined by 
Gillette (<?), winters on the Russian olive {Elpeagnus umbullata ), and 
goes tq smartweed (Polygonum sp.) for the summer months. The eggs 
began hatching February 27, 1923, on the Russian olive. A young plant 
with lice was placed in the dark chamber, and the first migrants made 
their appearance on April 10. These migrants were then placed on smart- 
weed, which was transferred to the dark chamber to be subjected to the 
short day. The first generation became mature on smartweed April 25, 
and on May 24 the young of the sexuparae and males were first observed 
With the characteristic red dorsal stripe that is present on no other genera¬ 
tion. The first males matured June 2, whereas normally they do not 
make their appearance until the latter part of October. 
Gillette ( 8 ) records that in Colorado the second generation on Eloeagnus 
all acquire wings. Here in Tennessee most of the second generation ac¬ 
quired wings, but a few remained on the primary host as late as June. 
It is interesting to note that young smartweed growing in the greenhouse 
was in flower on March 26, when it was but 2 inches high. 
Aphis sorbi Kaltenbach.—The rosy-apple aphis has for its alternate 
host the common narrow-leaved plantain (.Plantago lanceolata). On 
