White Bluffs spokesman. [volume] (White Bluffs, Wash.) 1907-1938, 1927-04-01
Study Life History of
Aphids and Methods
OF Their Control
BY GEORGE L. ZUNDEL,
Former Extension Specialist in Plant
Diseases, State College of
Washington.

Washington.
The life cycle of aphids, and meth
DDS Of their control are important in
the control of mosaic, for certain
species of plant lice or aphids are the
means of spreading mosaic disease in
the potato field. Mosaic is caused by
a virus that circulates in the sap of
the potato plant When an aphid
feeds on diseased plant by sucking
the sap and then flies to healthy
potato plant and begins sucking, it is
capable of carrying the virus disease
to the healthy plant thus spreading
the disease in the patch.
At present we know definitely of
three species of aphids of worldwide
distribution that spread the mosaic
virus in potato patches. These three
species are known commonly as the
potato aphid," the Green peach
aphid," or as it is sometimes called,
"the Spinach aphid," and the duck
thorn" aphid.
In order for the potato aphid to
complete life cycle it must have the
rose and potato plants. The rose is
the normal plant upon which the eggs
are deposited in the fall. In the
spring they hatch out, forming wing
less females, known as "stem moth
ers." These are capable of produc-
ing other live aphids, some of which
are wingless and some winged.
Those that have wings fly from the
rosebush to the potatoes or some
related plant, such as the night shade,
tomato or egg plant. The wingless
females left on the rose later produce
other winged females which migrate
to the potato and related plants Dur
ing the summer several generations
of winged and wingless females are
produced on the potato patch, and the
winged females spread the disease in
the field. In the fall winged females
and males produced on potato plants,
fly back to the rose bush and there
generation of wingless egg-laying fe-
males are produced, and the life cycle
is complete.
The life history of the green peach
or spinach aphid is in general the
same as the preceding species, except
that instead of laying eggs on the
rosebush, they prefer the peach tree
or some other plant of this group
such as prune and plum trees. In
summer potato and related plants are
not necessarily the favorite plant
upon which they feed, sfhce when
they have a chance, they feed upon
the spinach and similar plants. How
ever, if potatoes are present in the
neighborhood, they do not object to
feeding on them.
In northern portions of the United
States this species has been found
during the winter on wild chokecher-
ries, and some of the wild plums.
When the climate is mild enough to
permit the ordinary method of repro
duction, the process goes on over win
ter. In such localities Overwhelming
eggs play less vital part in the life
history of this aphid.
Under special conditions, the buck
thorn aphid may be present in greater
numbers on the potatoes than the
other two species. This, however, is
somewhat unusual. The potato ordi-
narily is far from being it's favorite
summer food plant. 1t prefers mas
turtium and certain other plants.
Under ordinary conditions it likes to
be in the shade. If potato plants are
in the shade it is usually on the grow
ing tips; otherwise on the under side
of the lower leaves. Its life history
in general is the same as the preced-
ing types, with winged and wingless
forms, except that the eggs are laid
on the buckthorn. In Washington
this group of plants is represented by
our Ordinary CdSCdid LI6S.
No matter how careful the farmer
is in rogueing out diseased plants, if
he is still bothered with a heavy in
festation of aphids, his work might be
entirely void. Although these insects
are very small, they usually live in
colonies of several hundred or even
thousand. When one or two aphids
will ruin a good healthy potato plant,
it is important to control them. There
are a number of possible methods of
control; first, destruction of the over
wintering host plants; second, treat
ment of over-wintering host plants,
and third, treatment Of potato plants.
In considering the destruction of
the over-wintering host plant, the
question arises whether this plant is
more important than potato growing,
and whether it is feasible to destroy
the host plant. These questions must
be answered by each individual COM
munity.
Where potato growing is a very
important industry, it might be feas-
ible to destroy rose bushes, buck
thorn or peach trees, p e9lyiding these
are of no Economic Importance and
not very abundant. However, if seed
potato growing is in peach growing
district, it would be folly to destroy
the peach trees. Conditions in some