The San Francisco call., 1910-11-13

sciences is parasitology. In Cali
fornis this has been developed
20 q greater extent than elsewhere for
the conserving Of the great fruit and
vegetable producing industries for
which the state Is famous. Freed from
scientific verbiage. the essence of the
new science as applied 70 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
winter month from the high sierras)
are kept IN cold storage until needed
IN the melon fields and apple and peach
orchards. and millions OF minute para
sites are bred IN confinement. for dis
tribution wherever agricultural or hor-
ticultural pests make their appearance
within the confines Of the state.
It IS now regarded by scientists as
an established fact that every form
OF life has one OF 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
species that feeds upon vegetable It's
sues has insect foes that feed upon it.
Were Il not for these natural checks
upon insects that devour vegetation
their powers Of reproduction are such
that they would soon consume every
green thing.
Sometimes the insect checks upon
rests are predaceous in their habits;
tHat is 10 say. they pouuce upon the
pest insects and devour them. OF this
nature are the Iadybird beetles. of
which there are upward OF 1000 spe-
cies. which are the enemies Of all va
rieties OF plant lice and scale insects,
Sometimes they are parasitic-that is
70 say. they deposit their eggs in the
grub OF the pest, and as the young
hatch and develop they feed upon the
surrounding tissues, and the victim
(known as the ''host'O is killed long
before It reaches maturity. Strictly
speaking, the science of parasitology
has 10 do with the first named class
only. But, a matter OF fact, para
biologists concern. themselves with
any insects that destroy other insects
that are injurious. whether predaceous
or parasitic.
bated by means OF poisonous sprays,
dips. washes. powder end 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 are used extensively. The CHIEF
objections 70 them are that they are
clumsy expensive. inefficient and OF
only temporary effect. It IS claimed
that they have never yet resulted in
the determination or permanent sub
lection OF a single insect pest. The
orchard OF 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 rn,s
recurring annual expense is unneces-
sary. HIS remedy is to search the
world for the natural foe OF the pest
and put It TO work fighting the farm
er's ab< fruit growers battles. In the
absence OF either natural or artificial
checks. the only Limitation to the null
tiplication Of the pest is it's food sup
ply-that IS the tree or plant upon
which 1t feeds Similarly the only
limitation 10 the multiplication Of the
numbers OF q beneficial insect is it's
food supply-the pest upon which it
feeds Consequently, the more numer-
Gus and destructive the pest. the more
rapidly viii its check multiply once the
parasitologists have succeeded in in
PRODUCING II.
In every life zone nature has estab-
Ished balance between vegetable life,
insect pest and parasitic or predaceous
foes. AS long as this balance is un-
disturbed the insects that are capable
Of becoming pests (and this includes
ali 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 season OF
the year when desert conditions were
natural With an abundant food sup
pIy thus provided, plant lice thrive at