Evening star., 1924-01-13

out in Kansas scientists of the
United States Department of Agricul'
ture have been. busy stirring up an
insect war. For several months. they
have been backing the parasite
Piatygaster himealis in its formi-
dable offensive against the Hessian
ifiy. If the parasite is victorious in
driving out these Hessian hordes. the
farmers of the middle west will be
relieved of large annual crop
waste.
The Hessian soldiers sent over by
George III to fight American colon
lists proved largely harmless. but the
flies they brought with them in the
straw bedding Of their horses at once
Established themselves as permanent
NESTS. These insects, each no bigger
THAN pinhead. descend in droves
upon the midland wheat fields, where
they suck the juice from the wheat
stalks. leaving them dead. So far,
science has been unable to find a
poison that will affect them, but eX-
haustive study has revealed the fact
that they have very deadly insect
enemy in the tiny Platygaster.
than a speck when not viewed
Through a microscope, does not fisk
open warfare with the Hessian ny.
lit uses a much more subtle method.
posted upon the leaves of the young
wheat, and stings them. These eggs
;hatch and the larvae appear as usual.
but each larva contains from elght
to ten embryonic Platygasters. The
youthful parasites soon become very
lively, but the fly loses all it's pep, as
all the food it absorbs goes to reed
it's unWeloome guests. They care
fully refrain from injuring the vital
organs of their host until they reach
through the fly and emerge. The fly
dies without propagating Itself.
while the Platygasters rush triumph
antly off to sting some more fly eggs
and thus go on cleverly reproducing
their species.
Given plenty of encouragement. it
lis believed, the Platygasters will
eventually exterminate the Hessian
fly. which will mean their own ex-
termination also. But science is not
worried over the passing of the
|Platygaster once it has served the
purpose of man.
All Insects Have Enemies.
In fighting the various insect pests
that persistently challenge our do
minion of the earth, science is rely
ing more and more upon these crea-
lures natural enemies. Not many
insect species are afflicted with such
deadly parasites as is the Hessian
fy, but each is priced as food by
some aggressive foe. Various birds
and fish and toads have an enor-
nous appetite for insects, which Is
very helpful to farmers. Recent in
yestigation on this subject has shown
that several birds, which have them
selves been looked upon as pests, are
really of tremendous value to man
kind as a means of keeping down the
insect population.
Outstanding among these is the
English sparrow, which has won late
but generous recognition 4s y friend
of man. The sparrow, II has been
found, not only feeds upon the sew
enteen-year locust, asparagus beetle,
locust leaf miner, but upon the cater
drop worm. The Bob White, also
thought to be merely ornamental,
feeds upon the locust and olive scale.
The story of the Mormon pioneer
farmers whose crops were saved from
a plague of grasshoppers by the sud
we'll known, but there have been
many similar instances in the history
of American farming which are not
SO we'll known. According to w, l..
McAtee of the United States Biolog-
|ical Survey, bird f1ocks have often
destroyed insect plaques and their
eggs and larvae SO completely that
such species have never returned to
the localities whore they had
wrought great crop damage, or they
have been so reduced in numbers as
to be almost negligible. In most of
these instances. the relief by birds
came at a time when the efforts OF
farmers to eradicate the pests had
proved fruitless and the crops had
been given UP a. lost.
The chief offender in the majority
Dof these cases was the Rocky noun