Los Angeles herald., 1891-03-01
ASPIDIOTUS ClTRINUS.
THE YELLOW SCALE AND IT'S NEW
FOUND PARASITE.
Board of Horticulture-M Matters of Inter
est to Orchardists.

Board of horticulture Matters of Inter
est to Orchardists.
The California state board of horticul.
ture has issued bulletin No. 81, which
treats Of "Internal Parasites, Discov-
cred in the San Gabriel Valley Recon-
mendations and Notes." 1t is compiled
by Quarantine Officer Alexander Craw
and is OF such interest to fruit-growers
that the HERALD this morning present s
it in full:
In the year 1872 an extensive orange
grower in the San Gabriel valley pur-
chased several small orange trees at a
San Francisco tree depot, and planted
them in his grove with the intention
of budding from them if the
varieties proved desirable, as pre-
vious to that most of the cit
rus trees in California were grown
from seed and allowed to bear fruit as
seedlings. The trees were found to be
infested with scale insect OF species
of Aspidiotus, which spread to the ad-
joining orange trees, and their presence
was detected by the mottled, sicklv ap-
pearance OF the leaves and fruit. A de-
termined effort was made to check it's
spread, and, if possible, stamp it out,
and the trees in the infested portion Of
the grove were cut back, the branches
burned, and the trunks and limbs
scrubbed; but after all this heroic treat
ment enough scales escaped to infest
the district.
To distinguish it from the 'brown
SCALE" Lecanium hesperidum, and the
"black SCALE" l.. oleae (the only scales
that were then attracting attention in
the state), it was named the "red
SCALE" from its reddish-yellow shell,
and was considered identical with
the red scale of Australia, Aspidi-
otus aurantii, Maskell; but quite recently
specific differences have been observed
that prove it distinct, and it is now
known as the "yellow SCALE" aspidiotus
citrinus, Coquillett.
Various solutions were sprayed on the
trees; sulphur and other substances
were inserted under the bark, and the
small roots were severed, and to the
ends leading to the trunk vials were
placed containing chemicals of various
kinds, in the hope that the roots would
take the chemicals up, and destroy the
scales; but in a great many instances
viz UiOOp WCiC uSStlOyCU iI5tcdu, anu
others injured and made unproductive
by reason OF the caustic or greasy prop
critics of the washes then used. In the
mean time the scale was slowly but
surely spreading, until now it is found
in nearly all the orange-growing sec
tions Of the valley and adjoining foot
hills.
In the spring OF 1880 Mr.. Cogswell, of
the Sierra Madre villa, informed me
that the scales were not as
numerous in his grove as they
had been, but he could not account
for their disappearance. He brought me
branches infested with yellow scales,
from which hatched number OF very
small chalcid flies this parasite. how
ever, had been discovered by Prof. d.
w. Coquillett two years previous, in the
extensive groves of A. B. & A. S. Chap
man but as the improvement in the
condition of the trees was more notice
able in the Cogswell grove, am OF the
opipiop. that.thev- -spsaad from, tl,a -iastAr..
to the Chapman and other orchards.
Various theories have been advanced
for the disappearance Of the yellow scale
in that section; the principal one is, the
excessive rainfall OF the winter OF 1889
80. But this theory can easily be ex-
PiOdSu Wy tllC ldCO Illdb VIC nave IStl
very heavy rains in previous winters,
and again, the improvement was notice
able and commented upon previous to
the winter OF 1SS9-90. ii the rains had
caused the destruction of the scales,
why is it that the decrease is
not all over the infested section?
l find that where the parasite has only
recently been found, or where / have
been unable to find them at all, the yell
low scales are as numerous as before. |
have recently hatched them by the hun
dred from scale-infested leaves taken
from an orchard wherein little over a
year ago the parasite was not known to
exist. The presence of such numbers
of parasitic insects-even if they are so
minute as hardly to be detected with
the naked eye-should be sufficient to
convince even the most skeptical that
the scales are succumbing to natures
remedy"
The fact that the scales appeared to
be on the increase last fall can be ac-
counted for. That is the time when
our scale pests have every season shown
the most increase, and that this was
noticeable in the orchards where the
parasite has been at work the longest,
is not very remarkable, as we have had
another identical case. When the cot
tony cushion scale was supposed to be-
cleaned out of some groves, and con-,
sequently there was no food for the
vedalia cardinals, the latter disappeared,
and few Of the former that escaped in
creased and caused considerable alarm;
but they were soon destroyed when the
growers placed a fresh colony of the
ladybirds on their trees.
YELLOW SCALE PARASITE.
Coccophagus citrinusx = New species
.(originaD.