The Liberal democrat. [volume] (Liberal, Kan.) 1911-1924, 1914-03-27

struction unnecessary. Winter de-
struction involves the necessity of
burning in November and December
all clump-forming grasses. such as
bunch grass and blue stem, which
grow along roadsides and ravines,
and in pastures, meadows, and waste
lands.
OF all the staple crop insects, the
chinch bug has been the only one for
which there was no insect parasite.
1t has long been thought that para.
site of the egg might exist but no
definite proof of such a phenomenon
was to be had. In April, 1918, chinch
bug eggs were collected in the field
that bore signs Of parasitism and on
being isolated there emerged from
them on May 10 three parasites.
With these three parasites as
basis the life history was carried
through the summer. The length OF
the life cycle was found to vary with
the temperature. During May and
June, the average length Of the life
cycle was from twelve to fourteen
days; during July ten days, during
August from thirteen to fifteen days
and during September from twenty
to twenty-seven days.
The exact number OF generations
has not been worked out, but there
are about nine or ten. From May 10 to
July there we're obtained four gen.
erations of adults. At this time the
chinch bug eggs became very scarce,
as 1t was the interval between broods
and thus it was not possible to con
tinue the life history work again I'M
til July 20. From then until October
four more generations were obtained.
The interval during which the life
history work was forced to be dropped
was about two weeks, or almost the
length of the life cycle, so that il
would appear that there might easily
be nine generations. The first para
sites were at work in the field about
April q and the last parasite OBJ
served in the field this fall was on
October IA.
The adult parasite Is a very minute
insect measuring about .03 of an inch
in length. Its life is very short last.
ing only few days and this short
existence is occupied in constant &C
tivity during the day in hunting for
mates and depositing eggs. Feeding,
il any, requires a very short time
and the main part of the insects life
is directed toward reproduction So
far it has not been possible to de-
( termine with any degree of accuracy
the numberq of eggs female can de-
post. In the experimental work each
female parasitized an average of five
or six chinch bug eggs. The largest
number Of eggs parastized by a
female was thirteen. Twenty-nine Ne
males that had not been allowed to
oviposit were dissected and the num-
Der of eggs in the ovaries counted.
The smallest number of eggs found
was thirteen and the largest, twenty
nine, while the average was twenty
three. The number of females greatly
exceeds the number of males. OF
fifty-one parasites collected in the
field forty-seven were females and of
the seven hundred eighty-six para
sites bred out in the laboratory, five
hundred twelve were females.
In considering the efficiency of this
parasite, it must be remembered that
the normal egg laying period of a
chinch bug is about two months and
that the life cycle of the parasite is
only about two weeks. Thus it is seen
that the eggs of single chinch bug
are exposed to three generations OF
parasites and instead of sixteen per
cent being parasitized, which is the
average per cent of parasitlsm for one
generation of parasites, about fifty
per cent are destroyed by the three
generations. Observations in the field
and experiments in the. laboratory
tend to bear this out.