Fergus County Democrat., 1915-01-14
ALFALFA SEED
PEST MENACE
RESEMBLES THE GNAT BUT is
RELATED eY AUTHORITIES
AS MORE DANGEROUS.
METHODS RECOMMENDED GROWERS

UIIIlUUO IllUUvIIvIlNOLU OtlOuuIIsO
WASHINGTON, Jan. 1O.-The al
falfa-seed destroyer, known as the
chalcis fly, does it's destructive work
in clover or alfalfa SEES, from the gulf
coast to the northern limits of the
United States, according to the United
States department of agriculture spe-
cialist, who has personally seen the
widespread devastatiohs of this pest.
BY harvesting severely infested crops,
by cleaning fence lines and ditch
banks, and by winter cultivation the
grower of alfalfa seed may help to con-
troll this insect. A new farmers bull
letin (No. 36), entitled, "The Chalcis
Fly in Alfalfa Seed" gives the details
of these methods of control, and may
be had free of charge on application
to the department.
The chalcis fly under the micro
scope is formidable looking insect,
but when seen in the field it is fire.
uuently confused with the gnat. These
pests may be seen in great numbers
flying over alfalfa seed shocks and
swarming over the sickle bar when the
alfalfa is being cut. The eggs are so
small as to be Invisible to the naked
eye and are deposited through the soft,
green seed pods directly into the soft
seeds when the pods are about half
grown. Immediately upon becoming
fly, the insect eats it's way out through
the shells of the infested seeds, then
through the green pods. Large pOr-
tions of the seeds are followed out in
this manner when they are still green
and growing.
The infested seeds which still con-
tain the living larvae of the insect may
be recognized by their abnormal shape
and usually by the dull brown color.
Some of the infested seeds, however,
retain their natural color, but they al
ways lack the glossy appearance OF
normal seeds. The extent to which
alfalfa seed is damaged by the fly is
not generally apparent, owing to the
minuteness of the insect and because
it's destructive work is accomplished
within the growing seeds. The alfalfa
seed grower can only estimate the
percentage of his crop destroyed by
opening a large number of the seed
pods and observing the infested seeds.
harvesting Severely Infested
Crops.
An alfalfa field is frequently found
with such a severe infestation by chal-
els flies that the grower considers it
Of insufficient value to be harvested
and simply drives in herd of cows to
pasture the crop. With regard to the
control of the chalcis fly for the pro
etction of future seed production, this
is costly mistake. Observations
show that many of the pods burst
open, while others are trampled to the
ground. Here great numbers OF in
tested seeds offer favorable conditions
for the Information of the chalcis fly
larvae. These, as mature flies, will
infest the seed crops the following
spring. Under such circumstances the
crop should be moved, removed from
the field. and stacked. 1t may then be
used as rough fodder; and if the re
naming straw is burned in early
spring the alternating larvae will be
destroyed.
Cleaning Fence Lines and
Ditch Banks.
The following facts emphasize the
Importance Of cutting the alfalfa along
ditch banks and fence lines, as we'll as
in the fields:
/. The earliest seed pods are founG
10 uGNClOp OIl Tie lSOidlcu anu Nl6ol
Gus growing plants found in sucl
places.
3 The earliest pods have an espe
cially large percentage of the seeds in
tested with chalcis fly larvae.
3. The chalcis fly larvae are able tt
pass completely through the first gen
GRAFTON in the earliest pods before thu
regular seed fields are sufficiently ad
yanced for oviposition.
This cutting should be done with tn,
harvesting of each hay crop, befor'
the seed crop is grown.
1t is sometimes necessary to hay
two or more irrigation bitches run
ming parallel, making it impracticabl
to cut the alfalfa between them. Il
such cases it is economy to fence TIL
bitches and use this land as a smal
summer pasture, thus preventing tn
development of alfalfa seed pods an
the chalcis flies.
Winter Cultivation.
In the process of harvesting the see
crop many pods containing infeste
seeds fall to the ground. Here the
remain until the following sprint
when the alternating insects emerg
thorough cultivation with an alfali
cultivator, at some time late in the ia
or in early winter, will sufficient
cover such pods and will prevent IL
emergence of most of the adults whe
the warm spring weather arrives.
Destroying the Screenings.
After the alfalfa is threshed tt
great mass of screenings which is lie
frequently contains large numbers
seeds infested with alternating Ia
vac. If the chaff, together with Il
screenings, is placed in compost pi
for three or four months, SO that
will become heated and decay, most
the insect life will be destroyed. U
less it is possible to treat the scree
ings in this manner they should
burned before the growing seas
opens in the spring.
Burning Fence Lines and
Check Ridges.
Many of the alfalfa seed pods alol
check ridges and fence lines may
destroyed by burning Off the wee