958 
Journal of Agricultural Research 
Vol. V, No. ai 
Aphis pomi also occurs in Canada, being found from Nova Scotia to 
British Columbia. It has recently been recorded in the Kootenai and 
Okanagan districts of the latter Province. 
Outside of Europe and North America few records of the species occur. 
It is present in Japan (18) and Dewar (12, p. 12) records it from Orange 
Free State. 
It is rather remarkable that this aphis has not become even more widely 
spread, since it is typically a nursery species and in the egg state is easily 
transported on nursery stock. 
Both in this country and in Europe Aphis pomi is usually abundant 
and particularly injurious at irregular intervals. Thus, in 1911 a severe 
outbreak occurred in Virginia, while in 1912 the species was very abun- 
Fig. i. —Map showing: the localities in the United States from which the Bureau of Entomology has 
actual records of the green apple aphis (Aphis pomi). 
dant in New England and New York. Similar phenomena have been 
noted from Russia. In some portions of this country, however, it seems 
to be always present and injurious. Gillette and Taylor (14) state that 
in Colorado “A. pomi is one of our very worst orchard enemies.” 
METHODS OF STUDY 
Experiments. —In initiating the experiments on which the following 
paper is based, twigs which bore eggs were collected at the time the eggs 
were beginning to hatch. These were kept under close observation. 
As soon as an egg hatched, the young stem mother was transferred to 
another twig kept in a vial of water. Although fairly satisfactory at 
first, this method of handling the food soon proved to be undesirable. 
Therefore there were substituted, first, dormant seedlings which had 
