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

| lower blades of the plants naturally
die, about the middle of June. At
about the same time the adults Of
the second generation begin to
emerge from these plants and deposit
eggs upon the wheat. These insects,
as were those of the first generate on,
are nearly all females, and they also
reproduce without the assistance of
the males, but they differ from the
earlier form in being large and in
possession of wings, which enable
them to attack fields at distance
from their origin. They prefer the
younger plants, and as the spring
wheat is small at this time. while the
winter wheat is old and tough, the
summer attack is concentrated upon
spring wheat, if there be any in the
vicinity. They attack it in much
the same way that the spring gen
Grafton employs upon the young win
ter wheat, and with the same result:
the smaller plants stimulate a luXu-
RANT growth, but remain short and
soon die, the large ones may produce
heads, a few inches above the ground.
but such heads contain no kernels.
Thirty acres of spring wheat near
ColfaX, Wash, were completely ruin
ed in this manner in the summer of
1907.
Since spring wheat is not so eX-
tensively grown as formerly in this
region, the summer adults are often
compelled to Outpost in winter wheat,
and in those cases the plant IS less
severely injured, because it is old and
tough; but the larva of the insect
and the resulting adult take the
same form and size whether they de-
velop in the tender spring wheat or in
the more mature winter wheat The
succulence of the former does not
cause~an increase in the size of the
larya which feed upon it, nor does
it produce a larger proportion OF the
winged individuals among the adults
On the contrary, it seems that au-
stere and unfayorable circumstances
tend to increase the number Of
winged adults, as a large percentage
of those reared from stubble collect
ed at Goldendale, st. German, ana
Wateryille, Wash, in the arid dis
tricts, have wings. The egg is placed
in a tender joint near the head ana
the larva matches and gnaws the in
ner surface of the stalk. too late to
prevent the formation of the head,
but early enough to shorten 1T and
hinder the filling of the kernels. To
ascertain the amount of this injury
1452 heads taken from an apparently
uninured field of winter wheat near
Pullman, Wash, were dried and
weighed. Thirty-nine per cent of
these were afterwards found to have
grown upon stems damaged by the
straWWorm, and the average wei; It
of the heads from these damaged
stems was % per cent below the av-
erage of healthy heads, although no
difference in size was noticeable an
til the heads were placed side by sid
when it was found that most of the
larger heads were those from Unin-
injured plants, while most of the
shorter ones were those from infest-
ed plants. Between heads of the same
size there was a difference of Z per
sent, which could not b detected eX-
cept by weighing.
Both the work of the spring brood
in fall wheat and that of the summer
brood in spring and winter wheat
are so carried on that often it
amounts to a very large percentage
of the crop, and even then he may
attribute it to some other cause. The
presence of number of unusEalIJ
rank and apparently sturdy plants
among the winter wheat does not
seem alarming, but the reverse; and
there is no other indication of the
work of the spring brood. Later,
when these Infested plants begin to
die they are concealed by the yell
lowing blades of the healthy plants.
so that even the trained entomologist
can hardly find them. The same is
true of the spring wheat which is at
tackled by the summer brood, while
the winter wheat plants attacked by
the summer brood are, as we have
just shown, so little altered in APP
pearance that the presence of the
insect can be detected only by weigh
ing the heads or splitting the stems
to look within for the larva.
Many of the larya remain in the
stubble if the grain is cut with a
harvester, and most of them if it is
cut with header They begin to pu-
pate during the later half of July, but