Imperial Valley press., 1912-10-02
ALFALFA WEEv|L'S WORK
DESTROYING UTAH CROPS

fornia horticultural commission ap-
pears the following article on the al
falfa weevil and the danger of i'm
portation to California, by G. f. Mer-
rill:
The presence of the alfalfa weevil
in Utah, Idaho and Wyoming and its
consequent damage there has aroused
in the minds of our alfalfa growers
an interest in the pest that is second
only to that felt by the fruit growers
in the Mediterranean fruit fly. In this
paper we intend to give the life his
tory of the insect, a brief discussion
of its Importance as pest in Utah.
the means practiced for its control and
the chances of its becoming established
in California.
In preparing our account of its
life history we have drawn freely on
bulletin 10 of the Utah Agricultural
College experiment station. The Alfal-
ia Leaf Weevil," by +. G. Titus, ana
on bulletin l12, bureau of entomology.
"Prelminary Report on the Alfalfa
Weevil." by f. NJ. Webster. Much of
the other information in this paper
was gathered by the writer during a
where he became acquainted with the
experiment station men and the agents
and experts of the bureau of entomol-
ogy who are engaged in fighting the
invader. The opinion of these men on
mary different points was asked for
and received In our conclusions we
have been guided largely by these
opinions. which far as we can learn
are well supported by facts.
Life History
The alfalfa weevil (Phytonomus pos
ticus) belongs to that large family of
beetles known as the Curculionidae or
snout beetles. Its greatest damage IS
done to alfalfa. but it also feeds on
certain species of lupines, peas, vetchas
and clovers. 1t passes through four
complete metamorphoses-t egg, the
larva. the pupa and the adult. The
eggs are small in size, oval in shape,
and when first laid lemon yellow in
color They later become dark at one
end and deep yellow at the other. The
larger part of the eggs is laid in
the spring time: in Utah during the
months of April. May and June. They
are arranged in clusters in feedin Z
punctures on the tender alfalfa stems
or in punctures made by the beak of
the adult solely for the purpose of
oviposition. The number placed in
each cavity varies from two to 80
with about 10 as general average
1t is by no means unusual for a
healthy female to deposit several hun
dred eggs if conditions remain suit
able throughout the egg laying pc
riod.
The time required for Matching var
les considerably. Under ordinary con-
ditions from 10 to IL days are neces-
sary.
When first hatched the larvae are
small. active and begin at once to feed
en- the inner parts Of the stem i'll
which they are hatched. They feed
III this location for three or four days
and then with relatively few excep
tions emerge and work their way W
on the outside of the stem until the!
find leaf bud into which they may
eat and grow in more or less com
plete concealment. The larvae pas:
through three moults and reach tn,
pupa stage in three to seven weeks
When full grown and about to pupate
of a plant or among pieces of bari
and litter on the ground and ther,
! spins a cocoon, composed of fine whit,
threads. Before pupating the insec
remains in the larval stage within the
cocoon from three to five days. Abou
nine days are passed in the pupa state
and within a day after the transfer
nation the adult leaves the cocoon.
The adult weevil is small beetle
less than onefourth of an inch long
| The body is covered mainly with short
dark brown hairs, among which ar,
! clusters of gray and black ones; as
a result the beetle has the appearance
/ of being brown in color, spotted viii
black. Individuals from which the hair
has been rubbed appear very dark
brown or even black in color.
The adult weevil is an active feed
eT and damages the stem, leaves and
buds of the alfalfa plant. The sexes
are almost evenly represented. Some
points in the habits of the weevil are
not yet fully determined, but it is
known that some individuals mate soon
after emerging from the cocoons and
that as a result of these matings fer
tile eggs are laid, which appear tC
give rise to a second brood. But the
Sreater number of insects pass the win
ter before producing themselves. Will
the approach of cold weather the in
SectS become less active and seek al
most any kind of shelter, particularly
about the crown of the plant and ur
der all kinds of rubbish, trash or lit
ter in the infested fields or near them
When warm weather comes the wee
wills become active. mate and begin
the work of feeding and ovipositior
about as soon as the alfalfa begins tC
develop. Flights to new feedins
grounds also take place during the
spring, but these flights are not likely
to be so long as those of summer
Spread
The adult alfalfa weevil, as has bee,
stated, is an active crawler and flyer
The greatest spread probably take.
place soon after emergence from the
cocoon At this time the insects are
active, fly high and are probably car
ried long distances by the wind. This
conclusion is borne out by the fact
that the most rapid and complete dis
semination in the infested territory has
taken place in the direction of the pre-
vailing winds. Indeed, it is difficult
to account for the presence of the
pest in some of the infested localities
except in some such way as indicated
in the foregoing. Although the in
sect hides in freight cars, wagons, fruit
boxes, beehives, passenger cars and
countless other movable objects, there
is no well authenticated instance of its
establishment in new territory in
America by artificial means
importance as "a Pest
The greater part of the alfalfa grow
ing district of Utah is now infested -
a greater or less degree. The pest has
been established long enough in some
localities for growers and others 10