The San Francisco call. [volume], November 13, 1910, Page 12, Image 12

About The San Francisco call. [volume] (San Francisco [Calif.]) 1895-1913

Image provided by: University of California, Riverside; Riverside, CA

                
CALIFORNIA'S
SANEST
BUG HOUSE
The State Insectary
Leads the World in the
Propagation and Dis
tribution of insects
That Devour Insects
That Devnurthe Crops
John L. Cowan
ONE of the newest of applied
sciences Is parasitology. In Cali
fornia this has been developed
to a greater extent than elsewhere for
the conserving of the great fruit and
vegetable producing- industries for
which the state is famous. Freed from
eclentific verbiage, the essence of the
new science as applied -to agriculture
and horticulture is to put bugs to fight
ing bugs, or. in other words, to combat
Insect pests by Introducing their nat
ural enemies.
By far the most Important establish
ment In the world devoted to the en
couragement of parasitology Is the
California state insectary. located in the
capitol grounds at Sacramento. Here
millions of predaceous insects (notably
the ladybird beetles, collected In the .
\u25a0winter month from the hlg-h Sierras)
are kept In cold storage until needed
In the melon fields and apple and peach
orchards, and millions 'jof minute para
eltes are bred In confinement, for dis
tribution wherever agricultural or hor
ticultural pests make their appearance
•within the confines of the state.
Tt Is now regarded by scientists as
an established fact that every form
of life has one or more natural checks
that limit Its increase In numbers. Birds
constitute one of the most Important
checks upon the multiplication of insect •'
life, but it appears that every Insect
epecies that feeds upon vegetable tis
eues has insect foes that feed upon it.
\Ter« It not for^these natural checks
•upon Insects that devour vegetation
their powers of reproduction are such
that they would soon consume every
fTf^n thing.
PometimPß the insect checks upon
j-ests are predaceous in their habits:
t*iat Is to say. they pounce upon the
ptpt insects and devour them. Of this
nature are • the ladybird beetles, of
which there are upward of 2,000 spe
cies, which are the enemies of all va
rieties of plant lice and seal© Insects.
Sometimes thoy are parasitic — that Is '
to say, they deposit their eggs In the
grub of the pest, end as the young
hatch and develop they feed upon the
\u25a0urroundirg tissues, and the victim
(known as the "host") Is killed long
before it reaches maturity. Strictly
speaking, the science of parasitology
has to do with the first named class
only. But, es a matter of fact, para
fitolosiEts concern, themselves with
any insects that destroy other Insects
that are injurious, whether predaceous
or parasitic. ,
In most regions Insect pests are com
bated by means, of poisonous Bprays,
dips, washes, powder and gases; or by
hand picking; or even by digging trees
or plants out root and all and burning
them. Even in California these meth
ods arc used extensively. The chief,
objections to them are that they are
clumsy, expensive. Inefficient and of*
only temporary effect. It Is claimed
thnt they have never yet resulted In
the extermination or permanent sub
jection of a single Insect pest. The
"orchard or truck garden that has been
treated with insecticides this year must
be similarly treated next year, and
every year In the future.
The parasitologist contends that mis
recurring annual expense Is unneces
earv. His remedy Is to search the
•world for the natural foe of the pest
and put It to work fighting th« farm
er's ar.^ fruit grower's battles. In the
absence of either natural or artificial *
checks, the only limitation to the mul
tiplication of the pest is Its food sup
ply — that Is, the tree or plant upon
which it feeds. Similarly the only
limitation to the multiplication of the
numbers of a beneficial Insect Is its
food supply — the pest upon - which It
feeds. Consequently, the more numer
ous and destructive \he pest, the more
rapidly will its check multiply once the
parasitologists have succeeded in in
troducing !u ,
In every life zone nature has estab
lished a balance between vegetable life,
insect pest and parasitic or predaceous
locs. As long as this balance Is un
disturbed the Insects that are capable
of becoming pests (and this includes
all that feed upon vegetable tissues)
do no appreciable damage, owing to
the activity of their natural checks.
But man disturbs the life equilibrium
in various ways. By Irrigation and
cultivation' he brings vegetation for
ward in. certain regions at a season of
the year when ' desert conditions were
natural. With an abundant food sup
i>ly thus provided, plant lice . thrive at
a period when their natural checks are
dormant. This is the reason why the
melon aphis gained such a foothold in
the Imperial valley of California that
the extinction of the great industry of
'growing melons, • cantaloupes and cu
cumbers for early, shipment to the east
ern markets seemed imminent.
The condition was met by the para
sitologists of the state Insectary* Last
winter- they sent field agents to
the canyons of the high Sierras, where
they collected 1,707 pounds of lady
birds, or approximately 43,000,000.
These were placed in cold storage in
the insectary. Then when- the melon
aphis made its accustomed appearance
in the Imperial valley in April the lady
birds were shipped for liberation In the
melon fields. In April more than ; 11,
000,000 ladVblrds wtre- shipped from
the insectary to the Imperial valley
and millions mori in May, saving, the
melon crop, worth at least $500,000.-
Later in the season many millions". of
ladybirds were shipped to sections of
•the state in which aphid pests ap
peared on apple Vand peach trees.
Another way In which the natural
balance among all forms of life is dis
turbed is by the extermination of in
sectivorous birds. That tfiis has been
an- important factor in contributing to
the growing seriousness of rav
ages the whole country over can not be
questioned. But the disturbance of the
' natural : life equilibrium o with which
parasitologists are most- concerned is
that due to the importation of foreign *
Insects. Practically all serious ' pests
that worry the farmer, gardener and
fruit grower (such* as the "cotton boll
weevil, the San* Joee scale, tho gipsy
moth, the coupling, moth and hundreds
"of others) have been brought to America
from foreign countries.
Usually these "foreign pests are
brought to America unnoticed. A for
eign tree, shrub or flower is Imported,
and it is very likely that the almost
microscopic eggs of /some insect are
present on it, The plant takes root
and grows and the Insect egg's hatch.
Years may pass "before the Imported
Insect; in its new environment, becomes
sufficiently numerous to ; constitute a
menace to the form of vegetation upon
which it flourishes. : Then it is recog-^
•'' nized 'as a \u25a0 pest and poisonous, gases,"
yowders. sprays and other mechanl
cat : methods 6T 'control '\u25a0' are tried.
In its natural home that particular
insect probably did very little damage,
because it was held In check byj: Its
natural , enemy, in the absence of _ its
natural enemy its numbers "increase
with the amazing Vapidity character
istic ; of insect life, when an abundant
food supply is found,;so;that it devours
all before it, often threatening the very
existence. of important agricultural and
horticultural industries. 7 r ,/• •
In emergencies of this;, kind, all
known mechanical methods of contro
are resorted to, but permanent rellet .
comes only through the introduction of
the same Insect foea of the pest that
held it in check in its natural habitat
Recognizing this fact, Californ!a.has an
explorer in the field, ransacking the
remotest corners. of the earth In search
of beneficial Insects. Thlsis George
Compere, employed Jointly by the hor
ticultural commission of California and
the entomological bureau of West Aus
tralia, for no other purpose than to
search the world for the Insect ene
mies of agricultural pests. Similar
work Is clone by the field agents of the
federal bureau of entomology, through
whose agency some of the most impor
tant beneficial Insects „ have been , in
troduced; However, California has sys
tematized this work to a greater extent
than any other state or country, and
breeds beneficial Insects for distribu
tion to farmers and orchardists on a
larger scale than has ever before been
attempted.V ; , : \u25a0 -" . "/'.
/The breeding'of beneficial Insects. in
captivity to any, extent desired is sim
ply "a question of providing an abundant
supply/ of the appropriate; food -at the
fight time/ with the proper conditions
of light, heat and ventilation- for -Insect
development. The insectary consists of
a:large : number.of ] glass -walled { rooms,
arranged around a central "court.;, .Each
room is heated 'and' ventilated : inde
pendently; of all the others, and' so ar
ranged that the air can be pumped out
and fresh air supplied from the- base
ment, at any temperature desired. It
Is, therefore, possible to regulate the
temperature to the fraction of a de
gree. The only food upon which para
sites flourish is the pest that nature
designed them to hold in check. It Is.
therefore, necessary to keep an abund
ance of pest infested leaves, twigs and
fruit on hand, In order that the bene
ficial Insects may have a plentiful food
supply. ?-. .'.'•
Most Insects, whether beneficial or
Injurious, may be kept In a dormant
condition, of practically suspended ani
mation, by simply keeping them In a
room with a temperature too low to
promote development. In this way,
breeding operations at the California
state Insectary are reduced to the low
est possible* terms. . "When a pest Is
Inactive/ its parasitic foes at the/ in
sectary are kept In a dormant condi
tion. The moment . notice .Is received
that a particular pest has broken out
In" any. part of the state the parasites
of that pest are taken to an apartment
where Ithe proper, conditions of heat,
light and ventilation may be supplied,
and an abundance of their appropriate
food is furnished. Almost instantly
the dormant insects begin to awaken
to activity:- soon, the females begin to
deposit their^ eggs, and, in a very few
days the parasit" in^sts of the Insect
The San Francisco Sunday cau
ary are ready to make shipments of
thousands of insects. These are dis
tributed free to any part of the state
in which their services may be needed,
and the express company delivers pack
ages containing them and returns the
shipping cases when empty, free of
cost within, the limits of the state.
Breeding usually is carried on in
breeding cages, made by covering *
light wooden frame with, insect net
ting. "When the .matured insects issue
they al(ght on the walls of the cages.
The parasitologist then opens the door
of the cage and quickly places a wide
necked vial over the tiny insect. In
stinctively the insect flies back into th 9
vial and the operator repeats the proc
ess again and again until he has as
many in the vial a3 he desires. Usually
about t% parasites constitute a "col
ony." but much larger colonies are
often shipped.
That the parasitologists of the stat-J
insectary have "made good" Is not open
to question, as any one familfar with
the work of the institution well knows.
Among the pests that have been com
pletely subdued, one of the moat de
structive was the cottony cushion scale.
A little more than 20 years ago this
threatened the every existence of the
orange growing industry, shipments of
oranges falling from 8,000 carloads in
one year to 600 the next. It was
brought under subjection by predaceous
*nd parasitic foes introduced from
Australia, the country of Its origin
Similarly the black scale that threat
ened the- ruin of the olive orchards and
spread to nearly all deciduous fruits
la controlled .by a little ladybird (rhi
robiua ventralls) and a small internal
parasite (scutellista cyanea). The San
Jose scale has spread from ocean to
ocean and ha 3 led to jnore legislation
on the part of the various states and
foreign countries than all other insect
pests combined. It is no longer a
dangerous pest in California.- because
wherever it appears the parasitologists
of the state Insectary ship colonies of
Its natural enemies, which quickly
cause Its disappearance. Several varie
ties of ladybird beetles prey upon it.
materially lessening its numbers, but
its most Inveterate foe Is a minute
hymenopterou3 parasite known as the
aphelinus fuscipennis. Other once dan
gerous pests that have been completely
subjugated In the same manner are the
soft brown scale, the brown apricot
scale, the yellow scale and pulvinaria
lnnumerabilis. Many other pests are
partially controlled by Insect enemies
bred at the stato insectary, and tha
scientists In charge feel sure that time
labor and patience will enable them to
completely control every insect pest
that vexes the farmer and fruit grower
They accept It as axiomatic that nature
never makes a mistake, that for every
form of life there is a natural check to
prevent It from becoming redundant J
To find that natural check. lntroduc-J
it where needed and giv© It a chanc/
to perform Its mission Is the essencd
of tha scienc* ox naxasitolosy. ~