Democratic Northwest. [volume] (Napoleon, Ohio) 1869-1894, 1889-07-04
THE eRArS-pLAsr LOUISE.
Wheat Fields Infested by a Destruct
IFE i've Insect.

mo i've Insect.
The Illinois board of agriculture Is IN
receipt Of the following cOmmunicat
from Prof S. A. Forbes, State entomo.
lOgist, concerning minuteinsect found
In alarming abundance on the head;
and leaves of wheat and oats.
This insect, commonly known a.
the grain-plant louise fsiphonophora
avene), is an old world species, known
for over 100 years to infest small grain,
feeding, indeed, on a great variety ol
grasses and grass-like plants, including
wheat, barley, oats, rye, bluegrass, fox
tail and the like, but not injuring any
of the crop plants outside the family OF
grasses. The general observer may
readily distinguish 1t by its oval or OBJ
long shape, its small size when full
grown about that of the head of a pin),
by its color, varying from bluish-green
to pale brown, by its six slenderjointed
legs, and two feelers springing from the
head, and especially by two short black
tubes (the so-called honey tubes or
cOrnicles) projecting backward and up
ward from the hinder part of the body.
Some of these plant lice are wingless,
while Others have large, transparent
wings. On the heads of wheat it often
crowds the stem as thickly as it can be
packed between the kernels. Here 1t
does its injuries by sucking away the
sap on its way to the swelling grain,
thus shriveling or blighting the kerr
mel.
an America it was first noticed in
1861, when it literally thronged the
wheat fields of the northwestern States
and of Canada, from New York and
Pennsylvania nOrthward. Its injuries
first attracted attention in Illinois in
1866, and again in 1876 and 1878, since
which time it has not been here report
ed as especially injurious. 1t has been
collected by us in small numbers, how
ever, every year since 1882. Its amaz-
ing abundance this season seems due to
the droughts of recent years and of the
early spring, its enormous rate of null
tiplication enabling it to take rapid ad-
vantage of circumstance favorable to its
increase. A single female may give
origin in twenty days to more than q
600 900 young, these themselves then
multiplying at the rate of 100000 a
day. ..F tt Gf..af f.| i
1.-THE amount of its injury, depend
ing largely upon the weather, can not
be predicted, seasonable |
rains serving to check its mischief,
both by their unfavorable influence
upon the insect and by enabling the
grain to support the loss of say.
Serious injury has not been heretofore
from the same district for two
successive years. These insects infest
their food plants throughout the year,
passing from one to another with the
season. They are most con-
spicuous and injurious when the grains
infested are filling the kernel, at which
time they concentrate in the head. At
other times they are scattered upon the
foliage, upon which they produce rela-
lively little effect. The interval be-
tween harvest and seeding time they
pass upon volunteer grain and wild and
cultivated grasses. They have been
found in late fall and early spring, even
when the ground was covered with
snow, upon the roots of winter wheat
and rye, and here they seem to pass the
winter.
Doubtless, also, eggs are laid at
some season according to the usual
method of insects of this kind, but the
time and place are as yet unknown.
Besides their susceptibility to unfavor-
able weather they are subject to i'm
nense destruction by parasites, the
most useful of which are minute four
winged insects which lay their eggs in
he bodies ofthe plant lice, thus giving
'rigin to minute grub which feeds
lpon the tissues of crusts of plant lice
which have been thus parasitised may
,ften be seen among the living insects,
ZACH with round hole in the back from ,
which the mature parasite has escaped.
"The attack in force of this plant {
ouse is commonly so sudden and wide j
pread, and it numbers are so over 1
vhelming when it gets fair start that I
here is probably nothing to be done I
With it that is of any practical value. ,
10 sensitive creature can best be left
o the weather bureau and its natural !
I