Okolona messenger. (Okolona, Miss.) 1900-current, 1909-05-19
SPRING GRAIN APHIS.
Facts About the Screen Bug" by r
M. Webster, Agricultural De.
partment.


the insect fairly well in certain local.
ties, 1t would be too much to apply
this to the whole area of its distribu-
tion with the great variety OF climatic
influences and effects OF elevation.
Generally speaking the insect dur
ing the warm months is viviparous;
that Is to say, the females give birth
to their young and no males are pres
ent. In the fall there are to be found
both males and egg-laying females. In
the north the insect, at least to a GER
tain extent, passes the winter in the
egg stage; but during the mild winters
, there still remain in the field vivipar-
Gus mothers who simply cease repro
duction as the temperature lowers,
only beginning again when the wealth
er gets warm. OF course this charac-
teristic is intensified as we go south
ward and we should not be at Sall sur
| prised to find both males and egg-lay-
ing females in spring; and, indeed, 1t
would not be surprising If we find that
the dry season is more or less bridsed
over in this stage.
The pest increases very rapidly
young becoming fully developed and
and reproducing in six to eight days.
A single female may become the pro
genitor of so to 60 young, and long be-
for she has ceased to reproduce she
will have become a gre'at-great-gran
mother. So far as we are able TO learn
the number OF eggs produced by an in
dividual egg-laying female is very
limited probably less than half a
dozen. Il is therefore in every way
probable that it is to the viyiparous
females living over in the fields that
disastrous outbreaks in the southwest
are due. Thus these outbreaks become
more a matter of weather conditions
than anything else.
The insect is normally controlled by
| It's natural enemies. A little wasp
like insect known as Lysiphlebus tri
within bounds and prevent its occur
ring in destructive abundance. This
valuable little parasite passes its en-
| tire development within the abdomen
of the grain aphis, and the time re
! quired is about ten days, but varies
much with the temperature. They are
| entirely dormant with the temperature
below Sc degrees and thus it is that
mild winters followed by cold back
ward spring are extremely favorable
| 90 oil of
| bug, because the latter will continue
to breed with extreme rapidity, while
| its parasites are kept dormant, and II
| is only when the weather gets suffi
GENTLY warm and remains so for ter
days or two weeks that this natural
enemy gets the upper hand and finally
overcomes the grain aphis, which, un
fortunately, does not occur until aftel
| the pest has bred in immense swarms
in the grain fields and killed the crops
leaving the fields as brown as though
they had been scorched by fire.
AS to remedies, 1t seems to be the
case in the south that the insect firs
makes its appearance in spots in fall
sown grain, the earlier the grain Il
sown the more likely 1t Is to be In
tested. We have found that, taken IL
time, these spots may be treated by
blowing under. spreading straw upor
them and burning, or by spraying with
kerosene emulsion. If the spots are
very small this method is more prac
tical than may at first appear. After
the insects have once become thor
oughly diffused and abundant in the
field there does not appear to be any
way of preventing their destructive
work. We have tried rolling and
brushing fields with no beneficial re
suits. OF course the spraying of ar
entire field Is out Of the question.