342 
Journal of Agricultural Research 
Vol. VII, No. 7 
SUMMARY OF LIFE HISTORY 
The eggs of this species begin hatching early in April (about April 8 in 
1915) and hatching ceases in about a week (April 16 in 1915). The first 
stem mothers begin reproduction about April 25. From 5 to 7 genera¬ 
tions of the spring forms occur on apple in Virginia, although Ross reports 
the species all summer on apple in Ontario. The first, generation is wing¬ 
less. A few winged forms appear in the next generation and their per¬ 
centage to the wingless insects increases steadily in each generation until 
finally all the insects produced become winged. Intermediates may also 
occur, these acquiring the wingless habits and behaving like wingless 
insects. 
Migration to plantain commences about May 20, and most of the insects 
have left the apple by about June 20. A few may continue on apple till 
about July 1. 
From 4 to 14 generations of the summer form occur at Vienna, Va. 
These insects are practically all wingless, only a few occasional winged 
insects appearing. 
The first fall migrants become adult about the second week of Septem¬ 
ber (Sept. 13 in 1915; these insects were bom on Aug. 31). They 
remain on the trees until after November 1. (In the writers’ experi¬ 
ments they were produced till a much later period, but in the field they 
succumb to prevailing low temperatures more quickly than do either 
oviparous females or males.) 
Production of oviparous females commences about the middle to the 
20th of September, but very few are produced till early in October and 
their production is at its height about the middle of that month. Males 
begin to appear early in October, at the time the oviparous females 
begin to become adults, and the males also are most numerous about the 
last of October and early in November. 
Oviposition commences the middle of October and continues till the 
oviparous females are all dead. Some oviparous females may oviposit 
as late as the latter part of December in case excessive low temperatures 
have not occurred before that time. 
The life history as summarized is for the vicinity of Washington, D. C. 
LITERATURE CITED 
(1) Fonscoi«ombe, Boyer de. 
1841. Description des pucerons qui se trouvent aus environs d’Aix. In Ann. 
Soc. Ent. France, t. 10, p. 157-198. • 
(2) Kai*tsnbach, J. H. 
1843. Monographic der Familien der Pfianzenlause (Phytophthires). ... 222 
p., 1 pi. Aachen. 
(3) Koch, C. L. 
1854. Die Pfianzenlause Aphiden. ... Heft 1. Niimberg. 
