The evening times. [volume] (Grand Forks, N.D.) 1906-1914, 1906-02-24
Farmers Insect Enemies.

The wheat stems or culmS' are sub
ject to the attacks of the larvae of
certain minute insects belonging to
the parasite groups of the order Hy-
menoptera, which is represented by
the parasites of the Hessian fly, plant
lice; etc. This little group or SUBJ
family, to which these wheat species
belong, has diverged from the great
mass of its allies, and acquired
strictly vegetable feeding or phyto-
phagic habit instead of subsisting par
asitically on other insects. Several
of these species feed on wild and Gull
ttvated grasses, and several others on
the various small grains. The two
species which are specially destruc-
tive to wheat are known as the wheat
straw worm Usosoma sgrande, Riley
and the heat joint worm Qsosoma tri-
tici, Fitch. The habits of these two
insects are similar and result in SINH
lar injuries to the wheat crop, name
ly, weakening the stems or culms and
causing them to break and fall be-
fore the grain is ripe, and at the same
time weakening the plants and de-
creasing the yield.
The wheat joint worm is another in
sect long confused with the joint worm
of barley q. hordei, Harris), the hab-
its of which it exactly duplicates. 1t
is true gall insect, its presence be-
ing indicated by the oblong swellings
Or engagements caused by the, larvae
In the walls of the wheat stems. The
gals are commonly found at or near
the joints, and more commonly the
second joint, but may occur in the
vicinity of nearly every joint in the
stem.
The adult insect is a minute black,
four-winged fly. measuring in length
an eighth to less than quarter of an
inch, and closely resembles in appear
ance its own hymenopterous parasites,
end also the parasites of the Hessian
fly and like insects. The gals usually
occur in groups of three or four, and
sometimes in large numbers together,
greatly deforming and weakening the
stem.
On cutting these gals open, they
will be found to contain, when mature,
the joint worm larva, yellowish-white
in color, with its jaws or mouth-parts
tipped with brown. In the larval and
lupal stages this species resembles it's
ally, the straw-worm usosoma tritici.)
This species is believed to be SINGLE
brooded, and to hibernate in its gals
In the wheat stems In the larval stage.
Transforming to pupa and adult insect
In the following spring or early sum
mer.
Thea wheat straw worm insect is
very closely. allied to the joint worm.
1t is distinguished, however, by It's
habit in living free within the hollow
stems or culms of wheat, and pro-
ducing no gall or reformation in the.
walls of the stem, as to do the former
species. Its work within the stem is
indicated by the eaten and torn inner
surface, and. as rule. 1t does not oc-
cur in sas great numbers as does the
Joint worm. It winters in the stem in
the pupal stage instead OF the laryal
: stage. az does the joint worm, and is
double rooded. i5si
There IL difference In appearance
Of the two broods. The adults Of the
two broods Of this insect are quite
dissimilar In appearance, and have
been described as distinct species.
The. adults. consisting Of both sexes
coming from the over-wintered pupae,.
are rather minute. and the females are