oe 
bo 
shoots of plums in spring. The stunting 
effect of its injury is sometimes very no- 
ticeable on the trees. The summer gen- 
erations live on grasses. 
CHERRY 
The Black Cherry Aphis 
Wyzus ceras. Fabr. 
This is a jet black shiny louse with 
long slender black cornicles. It infests 
ehiefiy the heads of young shoots and is 
often very injurious, checking consider- 
ably the growth of the tree. The life his- 
tory and control are similar to those of 
the Green Apple Aphis. 
PEACH 
The Green Peach Aphis 
Myzus persicae Sulz. 
The majority of the individuals are 
green or green with black markings, but 
some are pink, reddish-brown or yellow. 
This louse measures about one-tenth of 
an inch in length. No other aphid with 
such a wide range of food plants as the 
Green Peach Aphis is known. Its food 
plants include nearly all deciduous fruit 
trees, nearly every vegetable, many 
greenhouse plants and numerous weeds. 
In Colorado and Missouri it is often quite 
harmful to peaches and other stone fruits, 
but on the Pacific Slope it is rarely in- 
jurious to fruit trees. The life history 
is somewhat similar to that of the Rosy 
Apple Aphis, in that the third generation 
migrates from fruit trees to weeds, veg- 
etables and greenhouse plants. In the 
fall occurs a return migration to the 
fruit trees on which the winter eggs are 
deposited. In California viviparous lice 
may be found throughout the year on 
weeds and in greenhouses. The princi- 
pal injury occurs to fruit trees in the 
spring, the lice feeding on the young 
fruit buds and weakening them to such 
a degree that they finally shrivel and fall 
off. Later the foliage will be curled by 
the lice feeding thereon. 
Control 
As the lice hatch fully two weeks 
before the buds open a winter wash may 
be applied very successfully at this time. 
The winter sprays recommended for the 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
Green Apple Aphis are successful in com- 
bating this aphis. Black Leaf “40”, 1 
to 1,000, or Black Leaf, 1 to 70, is also 
effective. After the trees are in foliage 
the tobacco extracts may be used effect- 
ively, but spraying should not be delayed 
too long as the lice are very hard to 
reach once the leaves are curled. 
The Black Peach Aphis 
Aphis persicae-niger Smith 
This is a native American species dis- 
tributed all over the United States. Both 
Winged and wingless viviparous females 
are shining black and the young lice are 
brown. The louse infests roots as well 
as the aerial portion of the tree. Its 
life history is somewhat similar to that 
of the Woolly Apple Aphis. In winter 
only the wingless root forms exist. Some 
of these migrate upward in late spring 
and found colonies on the leaves and 
shoots. These colonies remain through- 
out the summer, the winged individuals 
migrating to other trees. The sexed 
forms are as yet unknown. The root 
form occurs chiefly on the smaller and 
more tender roots and thrives best on 
light sandy soils 
Control 
The aerial lice may be controlled by any 
of the contact insecticides suggested for 
the Green Apple Aphis. For the root 
form the surface soil above the roots 
should be scraped away and tobacco dust 
applied. This will be leached down by 
the rain. 
CURRANTS AND GOOSEBERRIES 
The Currant Aphis 
My2zus ribis L. 
This is a small green or yellow louse 
with black markings which curls the 
terminal leaves of the shoots of currants 
and gooseberries. Its life history is sim- 
ilar to that of the Green Apple Aphis. 
As the lice collect on the under side of 
the leaves it is necessary to use an under- 
spray nozzle to reach them. Any of the 
contact sprays suggested for the Green 
Apple Aphis may be used but applica- 
tions should be made before the leaves 
are badly curled. Very often hand-pick: 
ing of the curled leaves will suffice to 
clean up this pest. 
