8 Farmers’ Bulletin 1128. 
she begins producing young at an average of 6 a day. The stem- 
mother lives from a month to six weeks. 
The offspring of the stem-mother may either become winged or 
remain wingless, and this condition may continue for at least 7 gen- 
erations, so that during these generations both winged and wing- 
less forms are to be found upon the apple. Occasional colonies of 
wingless forms may be found throughout the summer upon the apple. 
The winged forms, however (PI. I, D), when mature fly to plantains 
and settle upon the underside of the leaves, or upon the flower stems, 
where they produce young (Pl. I, I, E). They live principally upon 
the species known as rib grass, long-leafed plantain, or buckhorn 
plantain. This migration to the plantains continues, in the vicinity 
of Washington, from the middle of May until the first part of July. 
On the plantains the insects continue to reproduce during the sum- 
mer months. Most of the forms produced on these plants are wing- 
less, although a few winged ones occur throughout the summer. 
The color of these forms is yellowish green, in contrast to the pink 
or rosy color of those upon the apple. From 4 to 14 generations of 
the summer forms occur upon plantain in the vicinity of Washington. 
In the middle of September winged forms, consisting of fall mi- 
grants (agamic females) and males, begin to appear upon the plan- 
tains. These winged forms are able to live and reproduce only upon 
apple trees or closely related species. The fall migrants leave the 
plantains and settle upon the underside of the apple leaves (PL. I, 
H), where they produce the young egg-laying females. These egg- 
laying females are wingless and orange-yellow (Pl. I, K). The 
males, which are similar in color to the fall migrants, often being 
nearly black, fly from the plantains and find the egg-laying females 
upon the trees. Here mating takes place and the females deposit 
their eggs about the middle of October. As later females are pro- 
duced by later migrants, egg-laying continues until freezing weather 
has killed all the females. 
THE GREEN APPLE APHIS.’ 
The green apple aphis lives on the apple throughout the year, and 
infests the tender terminal growth, causing the leaves to curl, as 
shown in Plate II, J, and figure 4. In young orchards by midsum- 
mer the shoots and leaves of the trees may be more or less generally 
1 Plantago lanceolata. 2 Aphis pomi De Geer. . 
DESCRIPTION OF PLATE II. 
Tue GREEN APPLE Apuis: A, Apple twig in spring with healthy young leaves; B, a leaf yellowed 
by attack of young aphids; C, a twig badly infested, showing sickly and stunted opening leaves; D, young 
aphid of first generation; E, mature aphid of first generation, a stem-mother; F, G, young and mature 
aphids of wingless summer generations; H, winged aphid of summer generations; 7, wingless summer 
form, side view showing the sucking beak; J, terminalshoot of young tree with late summer infestation 
of aphids; X, a leaffrom J showing aphids and their shed skins on uncer surface; ZL, a male aphid, pro- 
duced only in fall; I, asexual female, produced only in fall; N, eggs, yellowish when first laid, turning 
through green to black. 
DESCRIPTION OF PLATE III. 
GREEN APPLE APHIS ON OPENING APPLE Bups: Winter eggs and newly hatched aphids on opening app}8 
puds; young aphid much enlarged at right. 
