Pullman herald. [volume] (Pullman, W.T. [Wash.]) 1888-1989, 1910-07-08
THE STRAW WORM.

letin on the Wheat StraWW0rm, VIII
ten by Geo. |. Reeves and published
by the U. S. Department of Agricui-
ture:
The wheat strawworm, by reason
of it's relation to both the climate anu
the farm methods of the most pro-
ductive portion of the Pacific North
west, is capable of great injury to
wheat growers. Though its greatest
inroads are made upon spring wi eat,
it is winter and volunteer wheat
which render those inroads possible.
Its work is of such nature that it
passes unobserved, unless an attack
of unusual severity causes the FARM
er to scrutinize his fields more close
ly than he is accustomed to do. The
constant small losses occasioned b.
this insect and the possible destruc-
ton of the crop over considerable
areas may be prevented by such
measures as every good farmer en-
ploys to maintain the fertility of his
soil, secure a good seed bed retain
moisture and eradicate weeds.
The strawworm may be found
wherever wheat is grown in the
| Columbia basin, that great and fer
tile plain of varying topography and
climate which is enclosed by the
Okanogan Highlands on the lo tn,
the Rocky Mountains on the east,
the Blue Mountains on the south, and
the Cascade Mountains on the west
but it is not equally destructive over
all that territory. The central and
| western parts of this basin, except in
| the Goldendale and Horse Heaven
| districts, are arid, producing liUle
or no wheat, and strip east of this,
known as the dry farming region,
where the scanty rainfall makes it
| necessary to summer-fallow the land
every second year, is by that I'll AS
protected from serious injury; but
the eastern zone, strip 200 nile
long, included between the dry farm-
ing area and the upper Limit of
| wheat culture at the elevation of
5000 feet, affords ideal conditions
for the production of small gram
and also for the propagation of this
| insect. The climate is characterized
by mild winters suitable for the
growing of winter wheat-cold, wet
spring weather, such as is desirable
for all small grains, and hot, dry
summers perfectly adapted to the ma
turing and harvesting of the crop.
The soil is such that after more than
thirty years of domesticn Uwsouth
| thirty years of almost continuous
production it still yields 80 to 40
bushels of wheat per acre. These con-
| ditions encourage the seeding of
wheat year after year upon the same
! ground, and such a practice, together
with the presence of winter or late
volunteer wheat, supplies the re-
quirements for the unhindered multi
plication of the strawworm. Owing
to the drought of summer wheat
it usually does not terminate until
about the same time as the fall soNn
wheat, and the significance of This
fact appears when we come to study
the insects life history.
The 1sosOma passes the winter IN
the larval or pupal stage and reaches
| maturity early in April 1t gnaws
it has hibernated and deposits it's
eggs in the heart of the young ants
of winter or volunteer wheat, which
must be near the place of emergence
since the generation is largely wing
less and it's effective range as meas
ured by the spread into an adjoining
field is not much more than IL feet.
The food plants of the early genera
ton may be supplied by winter wheat
or by volunteer wheat not too far
advanced to attract the insect. The
oVipOsition is finished before any
spring wheat is up, so that that crop
suffers no attack from the first gen
Grafton The winter and volunteer
wheats lend an essential aid to the
perpetuation of the species.
The larva, when it matches from
the egg is surrounded by the most
delicate tissues of the plant and feeds
upon them, destroying the young
head and thus eXcavating a residence
to accommodate its rapidly increas-
ing size. The outer, tougher layers,
which it does not attack, gradually
become fleshy, stiff and brittle, form
ing a hollow, bulblike swelling at
the base of the plant. This enlarge
ment is discernable from the out
of the infested plant and its pres
ence may be verified by squeezing
the crown of the plant between the