Imperial Valley press., 1925-11-28
By B. A. HARRIGAN
Horticultural Commissioner Of I'M
perial County

per1al county
Prac tically every year many
thousands Of dollars worth of crop.
in Imperial Valley have been lost
by the attacks of small insect.
known as aphids. There are many
species of aphids, but the one most
abundant and most destructive
throughout the valley is known a:
the melon aphis. This insect con
tinues to live throughout the winter
months on various weeds, rs well
as on cucumbers which are becoming
more and more winter crop. In
the spring of the year this melon
aphis becomes a pest upon melons
eantaloupes and cotton, as well as
other crops.
Control measures. such as spray
ing or the application Of other in.
secticides, are more or less unsat
isfactory. For this reason the
state insectarv for a number of
years supplied the growers with
quantities of lady beetles in the
spring for the purpose Of destroying
these aphids. A few years ago
however, the distribution of the
common lady beetles for this pur-
pose was discontinued.
Flourished For Awhile
with the discontinued introduc.
tion of large quantities Of lady beet
les and the growing Of winter Gu
eumber crops, these little aphids OF
plant lice have had a free reign
with regard to their rapid develop
ment and increased attacks on
crops. They are known to praeti,
cally every farmer, although their
appearance on different host plants
sometimes differs considerably. To
the cotton grower they are known
as the cotton louse; to the orange
grower they are frequently called
the orange aphis; the cucumber
| grower calls them the cucumber
louse and likewise to the melon
! grower they are known as the
melon louse or melon aphis and
Others frequently speak of them as
the green aphis.
Multiply Most Rapidly
By giving birth to from four tc
ten offsprings each day and develop
ing from the new born aphis to tho
adult stage in a period of from
eight to ten or fifteen days vary
ing weather conditions, many gen
erations are reached in a single
season and countless millions OF
aphids soon swarm over the leave:
Of infested plants. The kind hand
Of nature has favored these little
creatures by causing them to devel
op wings so soon as food plant:
begin to dry up.
The winged forms then fly
through the air in search Of new
and greener fields. But the exis
tenee Of Mrs. Melon Aphis is not
all bed Of roses because she and
her family are called upon by Lady
Beetle and her offsprings. The
common ladv beetle, especially one
known as Hippodamia convergens
is ravenous feeder and can des
troy many aphis in the course Of a
single day.
Are Voracious Eaters
! Whenever large quantities of food
are available for the lady beetles
! they become established on these
plants and soon deposit eggs which
in turn hatch to the larval stages
| These young lady beetles are even
more ravenous in their feeding hab-
| its than the adults and single lar.
vac can destroy from one hundred
to one hundred and fifty aphids in
the coNrse Of twenty-four hours
It is, therefore, very important that
these beneficial insects should be
established early in the season Sc
as to increase in abundance, to
gether with the destructive aphids
pests.
With this in mind. ouy office il
securing large quantities Of lady
beetles from every available source
to distribute throughout the county
and thereby do everything possible
to save the crops for the cucumber
melon, cantaloupe and cotton grow
ers. In addition to protecting
these crops the lady beet
les are of great value in destroying
the aphids on such crops as grain
alfalfa and various orchard trees
Under normal conditions lady beet
les gradually begin to leave the
valley during the extreme hot
weather and migrate into the
mountain canyons. After this
they have a habit Of collecting in
swarms and seeking shelter during
the cold nights and winter months
in hollow trees and under rocks
and pine needles.
Go Back Home At Night
These colonies are located ani
here the lady beetles may be col
lected at any time from September
until the snow gets too deep and
then again when the snow melts ir
the spring until the lady beetles
become warm enough to scatter dur
ing the warm parts Of the day. Late
in the afternoon these lady beetles
swarm back to their hiding place
where they seek shelter for th'
night and each day until warm sum
mer weather sets in they come out
in search Of food. During midsum
mer they scatter widely from thu
mountain ranges feeding upon vari
Gus forms Of smaller insects ant
insect eggs.