The Caldwell tribune. [volume] (Caldwell, Idaho Territory [Idaho]) 1883-1928, 1916-08-11
ALFALFA WEEv|L IS NOW
SPREADING FAST IN
THE WEST


Washington, D. c., Aug. 8-The al
falfa weevil is spreading away which
n axes 1t possible that sooner or later
every section OF the country viii have
to consider the problem OF guarding
against this pest. During the twelve
years since the weevil was introduced
into America it has been confined to
the Great Basin OF the West, but it
has been found this year by the bu-
reau OF Entomology at Malta, Nc
Cannon, Pocatello and Blackfoot,
Idaho, all we'll within the Snake river
drainage system, and at DucheSne,
Utah, IN the Colorado River system,
which like that of the Snake slopes
to the Pacific Within the Great Ba-
sin the weevil has sprad so far south
as Richheld into the alfalfa fields of
central Utah. The insect. in spreading
across the continental divide, Depart
ment entomologists say, is to be re-
garded merely as passing convenient
landmark rather than as surmounting
a barrier, for experience has not
shown that it spreads faster along
rivers than across mountain ranges.
Nevertheless, it is now many miles
nearer to important alfalfa growing
districts which have hitherto felt safe
from its attack.
Description of Weevil
A description OF the alfalfa weevil
and methods Of combating its ravages
are contained in a new publication of
the U. S. Department of Agriculture,
Farmers Bulletin 741. The spread
OF the pest has, as matter of fact
been slower than was at one time
feared; its progress has been steady.
In Utah and in small portions of Ida
no and Wyoming, where it now exists,
1t has caused al times loss of So
per cent of the first cutting of alfalfa
and total loss of the second cutting.
In order that farmers in those sec
tions in which the weevii has not yet
appeared may be able to recognize the
pest and to protect their crops from
it, the bulletin already mentioned con-
tains details of its habits and of its
appearance in the various life stages.
The weevil is most easily discovered
in the form of the full grown larva.
1t is then green worm-like crea-
ture one-fourth of an inch long with
black head and a faint white stripe
down the middle of the back. 1t feeds
upon the leaves of alfalfa mainly dur
ing late May, June and early July and
may be found by sweeping the tops
of the plants with an insect net or by
looking for the notches in the leaves
where it has fed. When the larvae
are numerous they destroy most of the
tender growth and cause the tops to
appear white making the field look as
if frostbitten when viewed from a dis
lance.
The adult insect is an oval, brown
beetle three sixteenths of an inch long
with prominent snout. Its color fire.
quently is nearly black. This beetle
is harder to discover than the larva
but on the other hand, it is present
in the field the whole year around
In winter it can be found by digging
about the crowns and roots of al
falfa plants.
The alfalfa weevil does not hiber-
nate definitely When the weather is
cool the adults are quiet, but with
warmer temperatures they quickly re-
sumo their activities. Egg laying be-
gins in early spring and is usually end
ed by June 10. One efficacious method
of controlling the pest, therefore, is
to destroy the eggs by pasturing the
first crop up to that time.
A similar result may be obtained by
cutting the alfalfa green md feeding it
as soiling crop.
IF this is not done the larvae hatch
in large numbers about the last week
of May or earlier and eat the alfalfa
leaves so rapidly that the plant Is un-
able to outgrow the injury, After the
field is cut the larvae which have been
feeding upon the first crop gather
upon thhe buds Of the stubble and fire.
ouently consume all the second crop.
By that time most of the insects have
completed their growing period and
have gone into the pupal or resting
stage. The later growth OF the crop
therefore, does not suffer from them
To protect the crop pasturing, as has
been said, is effective in the early part
of the season. The field should be
divided into two or three lots and eacf
lot should be pastured alternately, the
animals being left in it until the al
falfa has been eaten down close &c
the ground. The number and size Of
the lots should be proportioned to the
producing power of the field and thu
number of animals to be pastured SC
that each lot may be grazed abou
once in two weeks. Pasturng shoulo
be practiced until most of the weevi
eggs have been laid, which, in prac
tice. means a little later than th'
usual cutting time of the first crop
This method has the additional ad
vantage of providing an economical
method of fattening live stock: Com
bined with the proper feed of grain
alfalfa pasture is excellent for puttin'
on wei ght and it is said that man!
farms would probably be more profit
able if their management centere'
about the nasturinp of stock on alfalfa