a 
Piant Lice Insurtnc FouiAGE AND FRUIT OF THE APPLE 687 
HISTORICAL 
To determine when this plant louse was brought to America has been 
impossible because of the confused state of the literature. Due to the 
statements of Pergande (1904)* it has been generally held that the species 
is of recent importation. Pergande, in a careful study of Szphocoryne 
(Aphis) avenae Fabr., endeavors to clarify the synonymy of that species 
and concludes that it is identical with Aphis mali Fitch nec Fabricius. 
He states that the true European apple louse, Aphis mali De Geer (he 
surely means Aphis pomi De Geer, or Aphis mali Fabricius), was first 
observed by himself in the spring of 1897 and has since spread thruout 
the United States. That he was mistaken in his conclusions can be 
readily shown by a careful reading of literature. 
Fitch (1855 a) in his first report has undoubtedly confused Aphis 
avenae Fabr. and Aphis pomi De G. This is shown in his descriptions 
of so many varieties, in his summary of the life history of the species, 
and furthermore in his published notes in the Country Gentleman (Fitch, 
1855 b) and in his illustrations and notes in his third report (Fitch, 1856). 
In the Country Gentleman he inserts a letter from William Gilchrist, one 
of his correspondents, who reports on June 25, 1855, myriads of plant 
lice infesting his young orchard. These lice were injuring young fruit, 
were curling the leaves severely, and were congregated in great numbers 
on the tender twigs. Such are not the habits of Aphis avenae Fabr. (A phis 
mali Fitch), and Dr. Fitch was puzzled, as is shown in his comments on 
the letter. Fitch’s early observations had been confined to an infestation 
of Aphis avenae Fabr., with which were undoubtedly mingled some A phis 
pom: De G. Evidently the injury reported by Gilchrist was caused by 
Aphis sori Kalt. or Aphis pomt De G. or by both species. In his 
discussion of the life history Fitch certainly outlines that of Aphis pomi 
De G. If he did not copy the life history in its entirety from European 
authors, he must have made some observations which warranted such 
an accurate description of many of the activities of Aphis pomi De G. 
Fitch also records the observations of Gilchrist that Northern Spy and 
Red Astrachan are not so susceptible to attack as are other varieties. 
This is in agreement with the recorded experience of entomologists with 
reference to Aphis pomi De G. 
1 Dates in parenthesis refer to Bibliography, page 760. 
