The Hays free press. [volume] (Hays, Kan.) 1908-1924, 1914-04-04

ried out should render summer de.
struction unnecessary. Winter de-
struction involves the necessity OF
burning in November and December
all cIump-forming grasses. such -
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
ehineh bug has been the only one for
which there was no insect parasite.
1t has long been thought that a para
site of the egg might exist but no
definite proof of such a phenomenon
was to be had. In April, 1913, chinch
bug eggs were collected In the field
that bore signs OF parasitiSm and On
being isolated there emerged fr00
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
days; during July ten days, during
August from thirteen 70 fifteen days
and during September from twenty
to twentyseven days
The exact number OF generations
has not been worked out, but there
are about nine or ten From May 19 to
July there were obtained four gen
erations Of adults. At this time tha
chinch bug eggs became very scarce,
as It was the interval between broods
and thus it was not possible to con-
tinue the life history work again IN
til July %. 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
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 fail was on
October IA.
The adult parasite is q very minute
insect measuring about .05 OF an inch
in length. Its life Is very short last
ing only a few days and this short
existence is occupied in constant &C
tiTity 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 a female can de-
post. In the experimental work each
I IL Of FIv-k7
or six chinch bug eggs The largest
number OF eggs parasitized by
I female was thirteen Twenty-nine fe-
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 a single chinch bug
are exposed to three generations OF
parasites and instead OF sixteen per
cent being paTasitized, which is the
| average per cent Of parasitism for one
generation OF parasites. about fifty
per cent are destroyed by the three
! generations. Observations IN the fed
and experiments in the laboratory
! tend to bear this out