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U.S. DEPARTMENT OF AGRICULTURE,
ier BUREAU OF ENTOMOLOGY—BULLETIN No. 112,
eat oe LO, HOWARD, Entomologist and Chief of Bureau. :
PRELIMINARY REPORT'ON THE
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GOVERNMENT PRINTING OFFICE. eee ip
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BUREAU OF ENTOMOLOGY—BULLETIN No. 112.
Ee. O. HOWARD, Entomologist and Chief cf Bureau.
PRELIMINARY REPORT ON THE
ALFALFA WEEVIL.
BY
F. M. WEBSTER,
In Charge of Cereal and Forage Insect Investigations.
Issuep May 14, 1912.
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WASHINGTON:
GOVERNMENT PRINTING OFFICE.
1912,
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BUREAU OF ENTOMOLOGY.
L. O. Howarp, Entomologist and Chief of Bureau.
C. L. Martart, Entomologist and Acting Chief in Absence of Chief.
R. 8. Curron, Executive Assistant.
W. F. Tastet, Chief Clerk.
F. H. CurrrenveEn, in charge of truck crop and stored product insect investigations.
A. D. Hopxrys, in charge of forest insect investigations.
W. D. Hunter, in charge of southern field crop insect investigations.
F. M. Wesster, in charge of cereal and forage insect investigations.
A. L. QuAINTANCE, tm charge of deciduous fruit insect investigations.
E. F. Pururres, in charge of bee culture.
D. M. RoceErs, in charge of preventing spread of moths, field work.
Roiia P. Currre, in charge of editorial work.
MaBet Cotcorp, in charge of library.
CEREAL AND ForAGE INSECT INVESTIGATIONS.
F. M. WeEBstTeErR, in charge.
Geo. I. Reeves, W. J. Pumures, C. N. Arnsuige, E. O. G. Ketty, T. D. URBAHNs,
Harry S. Sirs, Geo. G. Arnsiiz, J. A. Hystop, W. R. Watton, J. T. Monet,
J. J. Davis, T. H. Parks, R. A. Vickery, V. L. Wr.pERMuts, E. G. Smy7tu,
HersBert T. Ossporn, Pure Luernsiy, C. W. Creet, E. J. Voster, R. N. Wu-
son, VERNON Kino, entomological assistants.
Nettie 8. Kioprer, ELLEN DASHIELL, preparators.
Mrr1am WELLES REEVES, collaborator.
2
LETTER OF TRANSMITTAL.
U.S. DEPARTMENT OF AGRICULTURE,
BUREAU OF ENTOMOLOGY,
Washington, D. C., January 2, 1912.
Srr: I have the honor to transmit herewith, for publication as
Bulletin No. 112 of this bureau, the manuscript of a preliminary
report on the investigation of the alfalfa weevil in Utah and adjacent
States. The investigations of the Bureau of Entomology in coopera-
tion with the Utah Agricultural Experiment Station began April 1,
1910, and still continue. The period covered by this report is from
April 1, 1910, to November 15, 1911. From April 1, 1910, to April
1, 1911, the bureau was represented in the investigations with but one
assistant. Since that time the force has been increased until eight or
nine persons have been from time to time employed. The information
given is exactly what the title of the bulletin implies, preliminary in
nature and not to be taken as conclusive in all cases. It is simply a
short account of what has been done within the period of time just
‘indicated.
Respectfully, L. O. Howarp,
. Entomologist and Chief of Bureau.
Hon. Jamres WILSON,
Secretary of Agriculture.
————
CONTE NAS.
Page
I IRIE Oe es NS oo ene Se Eee deemed aoe eee Seat : 9
First appearance of the alfalfa weevil in the United States.................. 9
IERIE elt ere rie ree Ae Sia Ld ee oe EOE es bend Qh Se 10
feveseeamons by the Utah Experiment Station...-......:..----:..--+-+-+-- it
Cooperation of the Bureau of Entomology and the Utah Experiment Station. - i
Cooperation with other bureaus of the United States Department of Agriculture. 14
Variety experiment........ em eer chest Stal pols a) SVU Ln Sete ea 14
Maeade aioe ol vertebrate enemies. .............-.5......24-2-0+---5--- 15
Semimeerrmm correctly determined.................--..--.-+----2--+2-ee0- 15
imupestamee ol a second species in Utah.........:...-. 22-0222. -22e- een ee-ee- 15
Description and seasonal history of the alfalfa weevil. ......-...---..-------- 15
Reem I eM Oh oo nw ene s Leda. he ais disiege ree Ss 19
Bpience ota partial second generation.......---.-------+---+-+--------- 20
a ae Oe te es ite et ace Lae ee rae oe 21
Lbs, DMIELOC: So Roe a eee cae eRe ee eRe 22
eMmmnInermE MA PITAL so POR cs cies eee ete od oe oe eee ee 23
ENN I ee a oe cides wee ee ee e's eet ke ee 24
DemerrmenOMOMGIESION. <2 J. 5 cc ee oon ee - nee ee eee ee eee 25
Wield experiments in destroying the alfalfa weevil. ...............---------- 26
Rene Mice Mem OMPCTIMENtS... 2... oe. ee be ee we ee eet - at
Sere me ENIMGM GS. 26.2 252 2. . se nps eee ee oe ee ee ee eee 27
Ses on im connection with irrigation. ........2.-..:..-----.----.---- 29
SENT EEECMT ee ate wt Se ee a gu ed 29
Reduction in quality of hay caused by the alfalfa weevil. ...............-.-- 30
EEE SS vo RS Se eR Sa ee 30
I le ee ees ee oe ae a bee LoS eee 31
Peegaeeous enemies... ..........-...- SE le ee SOE ae ned seeker a ot
Serene mie WE Pans (Cree ee ee ea ee cade cn alate a cele Ha eleie 34
MMSE OMIIARAG THES crcects.) 202 22% 5 ie PEL oe we Bek aoe bane nein vale 34
EE TU GUTS Scale ey UE OO an eee ae Cae cae ee eS 35
Unley aig RENO ERAS UC a als So Cae oo Ll aie oa aan wel 35
Pee romanian es paragi teed ih. a6 ode ok an ee es ee se oe 35
Pamees on laryeeiand Ue ./eec 212-25... c2.2- 52,58 5he2 ses AY 36
Pteromalid larval parasite............ eee ite Lig Tc ee 36
LETEGRT? TSE TE IPT SISS EiN ai oe ee eS ng a 2 38
I trea 2 oh cle wile SL Foils ewig eats Se 40
PIS Nm ecw ee ee ee OM oe Oe ota dle eee cbes 4]
ee es Se ae oe cee bees «dle 43
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IX.
ILLUSTRA TRONS.
PLATES.
Conditions favoring the spread of the alfalfa weevil. Fig. 1.—
Volunteer growth of alfalfa on vacant lots in Salt Lake City, Utah.
Fig. 2.—Volunteer alfalfa growing along the right of way of the
Oregon Short Line Railway, a short distance north of Salt Lake
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COOPERATION OF BUREAU AND STATION. 13
this fund, on April 1 a corps of entomologists was sent to Salt Lake
City, Utah, for the purpose of. carrying out a thorough study of the
insect and its ravages, with special reference to methods of control.
Gradually other assistants were detailed, until the number employed
in and about Salt Lake was increased to nine, exclusive of the student
assistant detailed from the State Agricultural Experiment Station.
The primary object of this work was, so far*as possible, to restrict
the insect to the area it then occupied and to use every effort, by
field experiments in measures of control, to devise means of lessening
its destructiveness.
In the meantime it has been learned definitely that the alfalfa
weevil was largely held in check in its native home by its natural
enemies. Mr. W. F. Fiske, in charge of the Gipsy Moth Parasite
Laboratory, having been detailed for work in Italy, kindly volunteered
to look into the matter of natural enemies of the weevil and, so far
as was possible without interfering with his other duties, to send over
to this country any insect enemies that seemed to him susceptible
of colonization in Utah. The object of this was to get these insect
enemies established, in so far as it was practicable to establish them,
at the earliest possible date, in order that they might have the oppor-
tunity to diffuse themselves during the spring of 1911. The value
of Mr. Fiske’s services at this time and in this direction can hardly
be overestimated. A more detailed account of this matter will be
found under a discussion of the introduction of the natural enemies
of the alfalfa weevil.
Very naturally the alfalfa weevil work divided itself into two
branches: (1) The field work, which included all mechanical! measures
for controlling the pest in the field; and (2) the work, necessarily
carried out largely in the laboratories at first, involved in the care
and management of the parasitic material dispatched by Mr. Fiske
from Italy. After the beginning of the fiscal year 1911-12 the experi-
ment station was able to add but slightly to the force of investigators.
By this time, however, the annual generation of the weevil had devel-
oped to the adult stage and laboratory investigations had largely
decreased.
While, as shown, the experiment station, owing to circumstances
not under its control, was not able to put into the field men trained
_ for this kind of work, the bureau was able by the aid of the imme-
diately available fund to overcome this difficulty. In the meantime,
however, the experiment station did its full share in other directions.
Dr. Ball, director of the station, did not hesitate to use his personal
and official influence whenever and wherever it could be of service in
advancing this work. Besides this, in a great many cases he was
able to relieve the bureau of expenses of field investigations as well
as to carry a number of other items of expense for which it would
14 PRELIMINARY REPORT ON ALFALFA WEEVIL..
have been impracticable for the bureau to have provided. It may
be stated, then, that from April 1 to September 1, 1910, the coopera-
tive work was largely under the direction of Prof. E. G. Titus of
the experiment station. From September, 1910, to April, 1911, it
was mostly carried on personally by Mr. C. N. Ainslie. During the
spring and summer of 1911 the investigation was carried on under
the general direction of those connected with the Bureau of Ento-
mology. Outside of the work on parasites, which has been carried
on wholly by the bureau, it is not possible distinctly to indicate just
what part of the cooperation was carried on by either the bureau or
the experiment station. This combination has been for the purpose
of accomplishing the greatest amount of good, and there has been no
inflexible line separating the work of the two cooperative bodies. As
a matter of fact, the results obtained could not have been secured
under any other arrangement or with less unselfish feeling than has
existed among those engaged in the investigation.
COGPERATION WITH OTHER BUREAUS OF THE UNITED STATES
DEPARTMENT OF AGRICULTURE.
Observations made by Mr. W. F. Fiske in the vicinity of Naples,
Italy, during the spring of 1910 appeared to indicate a possible
preference on the part of the alfalfa weevil for certain varieties of
alfalfa. Those varieties, notably, having a slender stem appeared
to be less freely attacked as compared with those varieties having
more robust stems. It was with the view of perhaps being able to
find a variety of alfalfa more or less objectionable to the alfalfa weevil
that a cooperative experiment was taken up with the Bureau of
Plant Industry.
VARIETY EXPERIMENT. _
The Chief of the Bureau of Plant Industry, therefore, detailed Mr.
Roland McKee, of the Office of Forage Crop Investigations, to super-
intend the seeding of a number of varieties of alfalfa (Medicago
- sativa) and the following closely related species: Medicago falcata L.,
M. ruthenica (L.) Trautyv., MW. lupulina L., M. cilraris (L.) All.,
echinus Lam., M. hispida nigra (Willd.) Burnet, MW. hispida confinis
(Koch) Burnet, M. hispida terebellum (Willd.) Urban, MZ. muricata
(L.) All., M. orbicularis (L.) All., and MM. scutellata (L.) Mill. The
tests of these varieties are being conducted on a farm in the vicinity
of Salt Lake City, Utah.
Such observations as it has been possible to make upon the young
plants involved in this experiment will be found recorded under food
plants. It will of course be understood that the most valuable and
decisive information bearing upon the relative extent of attack in
these different varieties of alfalfa can not be observed until the spring
of 1912. Therefore the information now given must be regarded as
only initiative,
DESCRIPTION AND SEASONAL HISTORY. 15
INVESTIGATIONS OF VERTEBRATE E\NEMIES.
_ In order to determine what assistance might be expected from birds
and other animals besides insects, arrangements were made with the
Biological Survey to send an assistant to Salt Lake in order to carry
out extended investigations along this line. Mr. E. R. Kalmbach
was detailed for this work by the Chief of the Biological Survey and
proceeded to Salt Lake, Utah, making continuous observations there
from May 7 to July 5, 1911.
It is not possible at the present time to give the results of this work
in detail, but a list of the vertebrate enemies observed attacking the
alfalfa weevil will be found under the heading Natural Enemies.
THE INSECT NOT CORRECTLY DETERMINED.
In the bulletin of the Utah Experiment Station, to which reference
has already been made, the name of the insect is given as Phytonomus
murvnus Kab., and this name was also applied to the same insect by
the writer in Circular No. 137 of the Bureau of Entomology, issued
April 20, 1911. It had been so determined by one of the best
American authorities on this order of insects. It has, however, |
proved to be a closely related insect (Phytonomus posticus Gyll.),
much more common and injurious to alfalfa in Europe, western
Asia, and northern Africa, and in these countries known generally as
_ P. variabilis Hbst., meaning literally the variable Phytonomus. - It
is, however, less destructive in the Eastern Hemisphere than it bids
fair to be in this country, because of its natural enemies at home,
which, as it pepe were not brought over with it when it was Ae
introduced.
APPEARANCE OF A SECOND SPECIES IN UTAH.
A much larger species, Hypera punctata Fab. (fig. 2), the clover-
leaf weevil, has recently been found about Malad, Idaho, by Mr.
_H.T. Osborn, and about Ogden, Utah, by Mr. E. J. Vosler, both
of this bureau. This is a larger insect than the alfalfa weevil, but
may be confused with it by the ordinary farmer. It had not before
been observed between the Rocky Mountains and the Cascades.
While known as a clover insect, this last beetle did some damage
to alfalfa in Virginia during June, 1910.
DESCRIPTION AND SEASONAL HISTORY OF THE ALFALFA WEEVIL.
The fully-developed alfalfa weevil, Phytonomus posticus Gyll. (fig. 1),
is a small, rather insignificant appearing beetle, slightly under one-
fourth of an inch long, of a brown color, mixed with gray and black
hairs arranged in indistinct spots and stripes on the back, as shown
in figure 1. Rubbed individuals may be very dark, verging on black,
16 PRELIMINARY REPORT ON ALFALFA WEEVIL.
‘The beetles pass the winter hidden away among matted grass or
other similar vegetation, including alfalfa, and, indeed, among most
kinds of rubbish anywhere, wherever they will be protected from the
weather. The beetles have also been found in early spring under
clods and about the crowns of alfalfa plants where the ground had
been roughly cultivated the previous autumn. The overgrown mar-
gins of fields and irrigation canals and ditches afford excellent places
for hibernation, some of which are shown in Plate II, figures 1, 2,
and 3.
With the first warm weather in spring the beetles become active
and diffuse themselves over the alfalfa fields, feeding upon any living
part of the plants that
have escaped the win-
ter or, as soon as it
commences to push
forth, on the fresh
erowth, both leaf and
stem. During some
years the beetles are
abroad in the fields in
Utah early in March;
in other and colder
springs it may be April
before they bestir
themselves. Latitude
and elevation, with
the consequent modi-
fications of tempera-
ture, will have much
to do in deciding the —
time of emergence
from winter quarters
Fic. 2.—The clover-leaf weevil (Hypera punctata): a, Egg; 6, b, b, b, inspring. Thev also to
larvee feeding; f,cocoon; i, beetle; k,same, dorsal view. (6, /,i, Natural
size; k, enlarged; a, greatly enlarged.) (From Riley.) SS extent hibernate
in the alfalfa fields.
As soon as the beetles have spread from their winter quarters out
over the fields they pair, and the females are ready to deposit their
eggs (figs. 3,4). As a matter of fact, however, pairmg has been
observed in the fall, and females taken while hibernating are ob-
served to lay 75 per cent of fertile eggs. According to the notes of
Mr. Fiske, made in Italy, they may place their eggs in the old, dead,
overwintered stems or even in the dead stems of plants other than
those of alfalfa, but in Utah the beetles refused to oviposit in dead
stems in the laboratory cages. According to Dr. Giovanni Martelli,
at Portici in 1909 the first adults which he obtained appeared toward
1 First contribution to the biology of Phytonomus variabilis Herbst. Bollettino del Laboratoria di Zoo-
Jogia Generale e Agraria della R. Scuola Superiore d’Agricolturg in Portici, vol. 5, March, 1911,
Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE II.
x re
“ Se PATS et Ae
nt
a
Fics. 1 and 2.—Hibernating places of the alfalfa weevil along fences and borders of fields
in the vicinity of Salt Lake City, Utah. (Original.)
Fig. 3.—One of the main irrigation ditches in the Salt Lake Valley, a favorable hiber-
nating place for alfalfa weevils. Photographed July 7, 1911. (Original.)
HIBERNATION OF THE ALFALFA WEEVIL.
DESCRIPTION AND SEASONAL HISTORY. aa
the end of April; at Acicastello in 1910 they appeared during the
first part of the second half of April. The maximum birth at Portici
in 1909 took place toward the end of the second decade of May and
the last adults were hatched near the end of May. At Acicastello
the maximum birth took place in the first decade of May and the
last were hatched during the second decade of the same month.
The females do not, however, always confine themselves to alfalfa
stems in ovipositing. On April 18, 1911, Mr. T. H. Parks found, eggs
of Phytonomus in punctures similar to those made in alfalfa in the
stems of the ground plum, Astragalus arietinus. Later Mr. C. N.
Ainslie found a number of these eggs in similar punctures, also in the
stems of this plant, there being usually six or eight eggs in each
puncture. Afterwards Mr. Ainslie found larve feeding on Astragalus
utahensis.
A few days before, Mr. Parks had also found eggs deposited on the
surface of leaves, on bits of trash, on the inside of a split stem of
grass, and, in one case, upon the bare ground.
In a very early spring some of the eggs may
be deposited outside of the plant, but evidently
this is not usual and occurs mostly when the
erowing stems of alfalfa are too small or not suffi-
ciently numerous to satisfy the requirements of ,.. 5 ghe alfalfa weevil:
the females in this direction. In preparing for Eggs. Greatly enlarged.
egg deposition the female punctures the stem thors Mustation-)
with her beak. The punctured stems and a group of these eggs in
place are shown in figure 4.
The method of oviposition has been described by Mr. Titus.t
Observations were made by Mr. C. N. Ainslie in which he found
that oviposition seemed to be accomplished by forcing the beak into
the fleshy tissues of the stem, sometimes into a hollow stem, in which
case the eggs are merely placed in the natural cavity. Where placed
in a leaf petiole, as is sometimes the case, the cavity for the eggs
must be necessarily eaten out. Generally in these eaten cavities only
4 or 5 eggs are placed, while in the hollow stems 15 or 20 seem
not uncommon. Once or twice Mr. Ainslie found eggs placed below
the enlarged base of the petiole. In this case the eggs were placed
in position through a hole made through the base of the petiole
and the mass of eggs was well protected by the hairy leaf buds
and unfolded leaflets behind the base of the petiole. Once in a
while the hole into the stem is eaten and the beak not merely forced
in, in which case the gleam of the yellow eggs can be seen through
the tunnel into the stem. When the opening is forced it is left more
or less filled with fibers that have been disrupted or forced aside by
the beak and the ovipositor. These fibers are often blackened from
1 Bulletin 110, Utah Agr. Coll. Exp. Sta., pp. 38-39, September, 1910.
26200°—Bull. 112—12——-2
18 PRELIMINARY REPORT ON ALFALFA WEEVIL.
some cause, perhaps simple oxidation, and appear quite different
from the ‘‘feeding holes” that aremuch more common. These latter
are either saucer or cup shaped cavities eaten into the plant stem or
punctures through the epidermis that are enlarged inside the stem.
In one alfalfa stem Mr. Ainslie found 4 egg “‘nests,”’ the holes being
in pairs. These pairs were one-half to three-fourths of an inch
between the separate holes, and each pair was in a separate node, the
pairs perhaps 3 inches dis-
' tant from each other. There
must have been 30 or 40 eggs
at least inthis onestalk. It
was picked from a vigorous
crown growing beside a ma-
nure pile, and nearly every
other stem in this crown con-
tained eggs. These shoots
were tall and had evidently
grown rapidly. Indeed this
seems to be the kind of stem
chosen by this imsect in
which to place the eggs;
shorter, woodier stems seem
seldom to be selected for this
Ne wi °
As observed by Messrs.
Wilson and Parks, assistants
of the bureau, the female
beetle, after excavating the
cavity for the eggs, inserted
her ovipositor and laid a
number of eggs before re-
moving the ovipositor from
the cavity. After this she
\ began beating it up and down
~ rapidly over the puncture as
Fic. 4—The alfalfa weevil: Larv= attacking a sprig of though pounding the orifice,
alfalfa, and ess, in situ; larva, enlarged, at right. sometimes but not always
Con’ tere ore excreting a drop of watery
material overthepuncture. This secretion when hardened appeared to
seal the opening. In some cases the arrangement of the eggs in rows
on each side of the puncture, as described by Mr. Ainslie, was verified.
Mr. Titus has described the egg * as being oval, rounded at the ends,
and when first deposited lemon-yellow in color. As the eggs incu-
bate they become darker at one end and a deeper yellow in the other
: Bulletin 110, Utah Agr. Coll. Exp. Sta., p. 34, September, 1910.
DESCRIPTION AND SEASONAL HISTORY. 19
portions. Under the microscope the surface of the egg is very
slightly roughened and sculptured.
_ Mr. Ainslie, who made a careful study of the egg (fig. 3) at oviposi-
tion and later, found that at time of laying the egg was a mere sac,
the shell being little more than a transparent, homogeneous envelope
or membrane. As segmentation proceeded this membrane became
very faintly pitted, and under the microscope with proper illumina-
tion barely discernible reticulations, both pentagonal and hexagonal,
were apparent. Both ends and sides seemed equally reticulated, the
areolation being perhaps a little smaller at the ends. After the larva
emerges the shell that remains is a transparent structureless mem-
brane with no trace of reticulation.
The number of eggs placed in a cavity varies greatly, there some-
times being not more than 2 or 3, ranging up to over 30; probably 10
would be about the average number, although these figures are of
course only approximate. Mr. Parks found that during the first half
of April the number ranged from 3 to 18, averaging 7 or 8; during
the last half and early May the number increased, 25 or 30 being the
maximum, with an average of 8 or 9. With reference to the number
of eggs that may be deposited in a single alfalfa plant, the one shown
beside the hat in Plate I, figure 1, examined on April 23—at which
date oviposition was still in progress and the beetles preparing for
Oviposition were still exceedingly numerous in the fields—indicated
that this plant at this date contained nearly if not quite 1,300 eggs.
Of course, in fields where the alfalfa grew up thickly there would be
a relatively less number per plant, but these figures serve to illustrate
the origin of the countless myriads of larve that swarm over the
_ plants in an alfalfa field and render more easy of comprehension the
destruction shown in Plate III, figure 1. The difference between
- uninjured and affected plants is shown in Plate ITI, figure 2, a and 6.
Other ravaged fields are shown in Plate IV, figures 1 and 2, in con-
trast with figure 3 of same plate.
In the Salt Lake Valley oviposition has been found to take place
earlier on the bench lands than lower down in the valley itself.
Eec-LAyInG PERIOD.
The period of egg laying is a matter of considerable significance,
_ since in some degree it will decide the question of efficiency or prac-
tical measures of control. As is usual with insects, after a female
has exhausted her supply of eggs she dies and there is no second
depositing of eggs by her during that season. The actual time
required for the individual female to deposit her supply of eggs is of
course influenced by the weather. In 1909 egg laying began in the
fields early in April, and eggs were found in greatest abundance during |
_ the last of May and the first of June. In 1910 egg laying began early
20 PRELIMINARY REPORT ON ALFALFA WEEVIL.
in March and was at its height by the middle of May, and Mr. C. N.
Ainslie found eggs in a rearing cage where beetles were confined
indoors as late as October 22, and others found them as late as Novem-
ber 10, and Mr. E. J. Vosler on December 6, while larvz of all sizes
were found rarely in the fields November 1. On this latter date the
sexes were pairing in the fields and some of the females contained
apparently mature eggs, but none could be found deposited in the
fields. In 1911 Mr. Urbahns found eggs and very young larve
March 31, and adults active in the field on a warm day (January
31, 1912); one feeding and one pair mating.
The time required for the eggs to hatch after being deposited is,
according to Mr. Titus, from 7 to 16 days, as observed by Mr. Ainslie
about 10 days, and according to Mr. Parks’s observations about 13
days. The three series of observations were made during different
years, 1909, 1910, and 1911, and, of course, under different tempera-
ture conditions. It would seem as though more or less pairing
is done in very late fall and the eggs deposited the following spring.
Of course, the scattering eggs and larve found throughout the late
summer and fall have little economic importance except to indicate
what might be expected in more southern localities, although even
in Utah some eggs probably survive the winter.
EVIDENCE OF A PARTIAL SECOND GENERATION.
The occurrence of larve up to the approach of cold weather in late
“fall has already been noted. Some of these at least might be ac-
counted for from the fact that overwintering females still contaming
eggs are found throughout July and early August; but that others of
these larve are the offspring of parents developing during the pre-
ceding spring is strongly indicated by the fact that the females
depositing eggs from which larve afterwards hatch are in perfect
condition, unrubbed, and apparently fresh.
Under date of October 19, 1910, Mr. Ainslie found that eggs were
being deposited in his rearing cages, dropped at random on stems
and leaves and even on the sides of the cage, but in no case did he
observe them placed within the stem. There were in this cage 150
adults, some of which were undeniably trim and fresh as though they
had just emerged, while others were pretty well worn, and there were
all intervening gradations. Adult females swept from alfalfa No-
vember 2 were found to have oviposited two days later. Adults
taken from the fields November 7 and kept indoors were found to
have deposited eggs within 2 or 3 days prior to November 30.
During the season of 1911 it was possible still further to substan-
tiate the foregoing by an extensive series of observations carried on
by several of those engaged in the investigation, and besides to add
even more evidence that some of these late-appearing larve are the
;
Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PEATE Tie
Fig. 1.—One of the worst infested fields in the Salt Lake Valley, showing injury to the first crop
of alfalfa, which was left uncut. Photographed June 26, 1911. (Original.)
Fic. 2.—a, Bunch of alfalfa uninjured by the alfalfa weevil.
b, Bunch of alfalfa badly injured by the alfalfa weevil,
showing growth made by first crop in the badly infested
fields. Photographed June 20, 1911. (Original.)
INJURY WROUGHT BY THE ALFALFA WEEVIL.
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IN
DESCRIPTION AND SEASONAL HISTORY. |
offspring of parents developing during the preceding spring. Eight
apparently fresh adults taken from the field on August 18 by Mr.
Urbahns were observed on the 21st to have oviposited to the number
of about 20 eggs, in confinement. Nine additional eggs were found
on the 23d. August 29, 10 adults, also seemingly fresh and un-
rubbed, were confined in a glass vial, and the following day about
50 eggs were found in the vial. Under the same date 112 beetles,
supposed from appearances to belong to the spring generation, were
collected by another member of the force at an elevation of about
7,000 feet, and the following day 75 eggs were found in the box in
which they were confined. Under the artificial conditions not all of
these eges hatched. This state of affairs continued and was observed
by several of the men to occur up to the end of the season.
While the beetles go into hibernation in nearly per-
fect unrubbed condition, they emerge in spring with
scales and pubescence removed to such an extent that
they are almost black in color, smooth, and shining.
This appearance so contrasts with that of the newly-
emerged adults of the new generation that the latter
can be easily separated at sight, and it was these latter
that were again and again observed to oviposit and their
eggs to hatch out larve.
Fig. 5.—Theal-
falfs weevil:
THe LARVA. Larva. Much
enlarged.
The larval stage is shown in dorsal view in figure 4 and = (Author's il-
. - : : . : lustration. )
in lateral view in figure 5. It is during this stage that ~
the pest accomplishes the greatest destruction, although the beetles
are of themselves capable of ruining the second hay crop of alfalfa.
Mr. Titus ' states that soon after hatching from the eggs the larve,
which at that time are quite active, begin feediug in the interior of
the stalk, sometimes remaining there for 3 or 4 days, and isolated
examples have been found that have passed into the second stage,
still inside the stalk. Larve have been found inside hollow stems
several inches away from the place where they hatched, working their
way upward, and later issuing through a feeding puncture. Usually
after 3 or 4 days they come out and work their way up the outside of
the stems and conceal themselves in a leaf bud, usually at the tip of
the plant. -
That the very young larve are capable of traveling considerable
distances to reach their food supply is not only indicated in Mr. Titus’s
published statement, but emphasized by the observations of Mr.C.N.
Ainslie under date of April 28, 1910. The actions of newly hatched
1 Bulletin 110, Utah Agr. Coll. Exp. Sta., pp.39, 40, September, 1910.
99 PRELIMINARY REPORT ON ALFALFA WEEVIL.
larve, as observed by him; were remarkably vigorous, very young
ones exhibiting great energy as travelers. Their mode of progression
is to reach forward and then, with a slight hump, to bring up the rear
part of the body. The head is at once thrust forward again. About
one move is made per second, and three propulsions will carry the body
forward 1 mm. When in doubt as to the direction to be taken, the
larva elevates the head and swings it from side to side until some
decision is reached, when the journey is resumed. The larve are
positively phototropie.
_ After working their way upward on the alfalfa stems the larve
begin to feed close down between the opening buds on the unfolding
leaves. Their manner of feeding there, as observed by Mr. Ainslie,
was by scraping off the epidermis with a sort of burrowing motion,
leaving only the veins and fragments of uneaten tissue. This selec-
tion of the terminal buds may be in part due to the shelter offered
as well as to the more tender and succulent nature of the plant
growth. Large numbers of young larve may, however, be found
feeding among the unfolding buds without being easily seen. This
feeding is further described by Mr. Titus‘ as follows:
In feeding, the larve bore holes into the buds [see fig. 4], working their way in
until they are often completely concealed inside the opening bud. The plant then
sends out other buds below this point, and usually other young larve are present to
destroy these, so that at times the growing tips of the plants become so injured as to
cive these tips the appearance of a gall. As many as 15 young larve have been found
feeding in the terminal bud of one stalk. Sometimes, before they are fully developed,
in the second stage, they pass out onto the leaves, at first eating the upper epidermis
only.
The larve, after the usual habit of those of the genus to which it
belongs, either-cling around the edge of the leaf or feed in a curved
position. This continual eating off of the fresh growth keeps the
alfalfa so reduced that it does not produce a first crop. Seriously
affected fields are shown in Plate III, figure 1, and Plate IV, figures
1 and 2, while a field that has not suffered from such attack is shown
in Plate IV, figure 3. From these illustrations a good idea of the
damage done by the larve to the first crop of alfalfa may be obtained.
LARVAL PERIOD.
From about 5 to 8 days after hatching from the egg the skin of
the larva splits and the old skin is pushed off, leaving the larva in a
new dress. This process is repeated after a period of from 12 to 20
days and again after about 12 to 30 days, as observed by Mr. Titus.
Mr. Ainslie in some instances got pup in 18 to 20 days during May,
1910. These variations in time are probably largely due to tem-
perature, which again may be due in part to elevation.
1 Bulletin 110, Utah Agr. Coll. Exp. Sta., pp. 40-42, September, 1910.
DESCRIPTION AND SEASONAL HISTORY. 93
When the larva is fully grown, it ceases to feed and seeks out some
place in the crown of the plant among the litter and trash or on the
ground among similar material, where it spins a cocoon (fig. 6).
CocOONING AND PUPATING.
The cocoon is composed of fine white threads and the construction
by the apparently blind larva was in part observed by Mr. Ainslie,
who describes its movements as follows: A larva was seen moving
about in its snow-white, almost transparent, gauzy, unfinished cocoon.
It proved to be spinning a closer mesh from within. Instead of
spinning the silk from a gland that opened into its mouth, as was
supposed, the fluid from which the silk is made is taken into the mouth
apparently from a gland in the caudal segment. The larva applied
its mouth to an opening or gland close to the anus, appeared to move
its jaws slightly, and then, with a quick
movement of the body, was: straightened
out as much as possible in its confined space,
and instantly the head was applied to the
inner network of the cocoon. A slender
glistening thread was seen leaving the
mouth, being attached glutinously to each
thread that it crossed. The larva worked
rapidly and nervously, nearly always car-
rying its new thread in a rather straight
line. From 30 to 50 seconds were required
to discharge a single mouthful supplying
thread for one-third or one-half a revolution re. 6.—The-alfalfa weevil: Cocoon.
inside the cocoon. Much enlarged. (Author’s illus-
When all the supply was exhausted, the arg
head groped aimlessly about for a few seconds, then was applied to the
caudal gland as before. The body would then straighten with a quick
movement and almost instantly the thread would be again flowing as
before. The new thread was guided skillfully across the meshes, rarely
if ever following the line of a thread already laid. A very slight jar
would cause a sudden halt for perhaps half a minute, then the opera-
tion would hesitatingly proceed. As the irregularly oval cocoon is
too small in any diameter to allow the larva to straighten out, the
larva moved about by thrusting its small head into a mesh, swinging
the body into the desired position; the head would then be moved
to another mesh and the operation repeated. The fluidity and amount
of the silk must vary as spinning progresses, the silk becoming more
viscous or less copious as the cocoon approaches completion.
The pupal period, according to Mr. Parks’s notes, during the middle
of May lasts about 9 days, the larve spinning their cocoons about 5
days before pupating. (A pupa is shown in fig. 7.) At the end
24 PRELIMINARY REPORT ON ALFALFA WEEVIL.
of the season, however, during August, when the temperature is
higher, the pupal period averages only 3 days, the cocoon being spun
only about 36 hours before the larva pupated. The adult leaves the
cocoon about a day after transformation, and unlike others of this
genus does not devour the cocoon. Although the insect has passed
through its transformation from egg to adult the injury
it causes is by no means ended. The beetles them-
selves not only feed upon the young growth (fig. 8),
but gnaw off the bark of the stems, and, together
with the larve still in the fields, in this way prevent
the alfalfa from springing up for weeks after the first
crop of hay has been removed. Two of such fields
are shown in Plate V, figure 3, and Plate VI, figure 3,
the ground being almost as bare of growing plants as
in figure 1, Plate VIII, where the ground has been
eee hci torn up with aspring-tooth harrow. The beetles some-
Much cnlarg-a. times cluster in great numbers upon a single plant, as
(Author's illus- jilystrated in figure 8.
tration.)
FOOD PLANTS.
In a series of experiments carried out by Mr. P. H. Hertzog, larvee
of Phytonomus posticus were placed in cages on various food plants,
both alone and with alfalfa, and it was found that they fed freely
upon the following plants, in combination with alfalfa:
Sweet pea, Lathyrus odoratus; Utah milk vetch,
Astragalus utahensis; string bean, Phaseolus vulgaris;
obtuse-leaved vetch, Vicia sp.; narrow-leaved vetch,
Vicia sp.; white clover, Trifolium repens; red clover,
T. pratense; alsike clover, T. hybridum; yellow sweet
clover, Melilotus indica(?); whitesweetclover, M.alba;
Medicago lupulina; M. echinus; M. hispida nijra; M.
hispida confinis; M. hispida terebellum; M. muricata;
M. orbicularis; M. scutellata; black locust, Robina
pseudacacia; fenugreek, Trigonella fenumgrxcum.
The following is a list of plants eaten by
the larvee when no other food was offered, but
refused when offered together with alfalfa:
Hedysarum mackenzii; Astragalus oreophilus; downy
lupine, Lupinus; sp. chick pea, Lathyrus sativus; Vicia Fic. 8.—The alfalfa weevil: Adults
atropurpurea; Vicia dispema; spring vetch, Vicia sativa clustering on ant ==
ae r ey ts ; alfalfa. About natural size. (Au-
alba; hairy or winter vetch, Vicia villosa; spider plant, _thor’s illustration.)
Cleome serrulata.
The following plants were refused by the larve even when no other
food was offered:
Everlasting pea, Lathyrus latifolius; round-leaved mallow, Malva rotundifolia; birds-
knot grass, Polygonum aviculare; garden pea, Pisum sativum; lamb’s-quarters, Cheno-
podium album; purslane, Portulaca oleracea; prickly lettuce, Lactuca scariola, perhaps
var. integrata; ground cherry, Physalis longifolia(?); bitterweed, Ambrosia psilos-
tachya; bitterweed, Ambrosia trifida integrifolia; rough pigweed, Amaranthus retroflexus.
PRELIMINARY REPORT ON ALFALFA WEEVIL. 95
MIGRATION AND DIFFUSION.
There are two periods during which the adult insects migrate, more
or less aided by the winds and perhaps to a less extent by other
agencies. Such as have not hibernated directly in the alfalfa fields
become active in early spring and fly about freely, seeking
such fields in which to deposit their eggs. This spring migration
covers a considerable period of time—about six weeks, as estimated
by Mr. Titus. As the females are more or less heavily laden with
eggs, however, the flight of the individual is perceptibly shorter than
in the second, or summer, migration, the season for which begins
early in June and continues for three or four weeks. Another reason
for the shorter flight in spring is that the beetles are searching about,
not for places of hibernation, but for breeding places. Having found
these, they naturally would not go farther unless carried by the
winds. In case of a summer flight, however, the conditions are
altogether different. This is the season during which most nomadic
insects become more widely diffused. At this time the beetles fly
high in the air and apparently over long distances. They are also
to be observed crawling about in almost every situation, as with the
larger species, Hypera punctata, which may be observed wandering
aimlessly over the pavements in the midst of large cities. Then,
too, they appear to float about freely on the surface of water, and
are doubtless carried long distances down stream by the current.
We know this is true in the case of irrigating ditches and canals, and
it is also true of the larger species just mentioned in case of streams
in the Kast. This habit of the beetles in hiding themselves away in
any crevice or aperture that will accommodate them doubtless has
considerable to do with their diffusion. As a matter of fact, how-
ever, it is absolutely impossible to lay down any law that appears
to regulate the diffusion of the insect. There are instances where it
would seem almost impossible to prevent the distribution of the pest,
and yet most careful examination has failed to reveal anything of
this sort. For a considerable time after the alfalfa weevil became
abundant about Salt Lake and Murray hay was shipped from these
points to Ely, Nev. This, too, in the midst of the season, when it
would seem impossible to transport hay from these points to its
destination without carrying greater or less numbers of the weevil.
Notwithstanding this, years have gone by, and during the summer
of 1911 two assistants examined the country about Ely most care-
fully without finding a single alfalfa weevil or any indications that
it had ever existed there. While it is possible to account for the
spread of the insect theoretically, we can not as yet account for its
diffusion to the northeast into adjacent sections of Wyoming and
Idaho. It does not appear to have entered Idaho by way of the
Cache Valley, although Mr. Titus found beetles on a coal car at
26 PRELIMINARY REPORT ON ALFALFA WEEVIL.
Cache Junction in 1910. It does, however, occur in the Bear River
Valley from Evanston, Almy, and Lyman, Wyo., northward into
Bear Lake County in extreme southeastern Idaho: Previous obser-
vations would indicate that by a natural diffusion the insect has
spread a distance of about 30 miles each year. As a matter of fact,
the beetles are continually bemg found where least expected, and
they have not been found where, judging from their habits, we would
feel most confident of their occurrence. ;
The most rapid dispersion of the insect during the last two years
has been toward the northeast from the original point of infestation
in the Salt Lake Valley. Its injury is now noticeable wherever
alfalfa is grown in the river valleys east of Ogden to the Wyoming
State line and northward to the southern extremity of Bear Lake.
It is known to occur, however, as previously stated, as far north as
Cokeville, Wyo., and southward to Evanston and Lyman, where
specimens were taken during the summer of 1911. This north-
eastward trend of diffusion in the weevil must be considered in con-
nection with prevailing southwest winds at the time when the beetles
are flying, and, in fact, careful search over the newly infested territory
seems to render it highly probable that to this cause is due this
northeastward diffusion. The finding of individual larve well
scattered over Wyoming fields with little or no indications of intro-
duction by human agencies, together with the finding of larve in an
irrigated valley isolated from other cultivated crops by 35 miles of
dry desert country, are conditions hard to explain in any other way
than that the south winds of spring and summer have resulted in
carrying flying beetles over low mountain ranges to fertile fields
beyond. To just what extent the winds are able to carry the adults
into new territory is not known, but at any rate migration in other
directions has taken place much less rapidly.
FIELD EXPERIMENTS IN DESTROYING THE ALFALFA WEEVIL.
Several extended series of experiments in destroying the alfalfa
weevil were carried out at various points in the infested territory
in Utah, but only those that have shown the best results will here be
mentioned.
Quite naturally, a measure that will destroy a greater or less
number of the insects and at the same time encourage the growth
of the plant, and is of practical application, will not only be the most
attractive one to the farmer but will result in a double benefit. For
this reason disking was looked upon as probably offering the best
results. It was thought that by disking and spraying a more rapid
growth of the alfalfa plants would be secured, and by following this
with the use of a brush drag a great many of the larve would be
crushed and destroyed. Mr. Ainslie’s observations made in 1910
4 ee ee ee ea ee eee ee
Se ae eee” il
v
FIELD EXPERIMENTS IN DESTROYING WEEVIL. 27
indicate, however, that the brush drag does not destroy as many of
the larve as one would suppose, and for this reason some harsher
measures have been put into application during the season of 1911.
STREET-SWEEPER EXPERIMENTS.
The ordinary street sweeper, such as is used in our cities, appears
to be a most thorough measure of destroying the pupe. This much
was determined by the Utah Experiment Station. A street sweeper
(Pl. V, fig. 1) was used in a field on June 22,1911. While examina-
ation showed that the result of this treatment, at this time, was to
kill most of the larve and pupe, it did not kill a great percentage of
the adult weevils, which had already developed in large numbers.
It would have been much better had this work been carried out about
two weeks earlier; not only the condition of this field but of others
in the neighborhood treated between June 14 and July 1 indicated
that considerable good had resulted from this treatment even at this
late season. On another farm, owned by Mr. Breeze, southwest of
Salt Lake City, a field was swept with the street sweeper about the
14th of June with a view of interfering with the work of the weevil.
By July 7 the alfalfa in the Breeze field was about 20 inches high
with very few weevils present. (See Pl. V, fig. 2.) Twenty days
later the alfalfa was 30 inches hich and in full bloom, being ready for
the taking of a second crop. Just across the road from this farm
was a field where no treatment whatever had been applied against the
weevil. In this field the alfalfa plants were only about a foot in
height and very much delayed (PI. V, fig. 3). This seems to indicate
that as a protection for the second crop the measure has considerable
value. The drawback here is in the expense of a street sweeper,
although of course where the members of a community club together,
or in case of very large alfalfa fields of several hundred acres, the
first cost of this sweeping machine would not constitute such an
important item.
WrrE-BrusH EXPERIMENT.
A 13-acre field of alfalfa 7 years old had been disked in the spring
of 1910. ‘The first crop of alfalfa was reported to have been reduced
to one-half by attack of the weevil. A weevil-collecting machine
had also been used on this first crop, but there were still enough of
the weevils left in the field to greatly retard the second crop. It was
disked and dragged again and a fairly good yield of the second crop
was secured. ‘This was also true of the third crop in this same field.
On May 15, 1911, there was a good stand of alfalfa in this same
field. One irrigation had at this date been applied. The plants
were a little over a foot in height, and while at the time, May 15, they
were in fairly good condition they were heavily infested with weevil
larve. The gathering machine was used twice between the 17th and
98 PRELIMINARY REPORT ON ALFALFA WEEVIL.
25th of May, and observations made at the time indicate that while
many of the full-grown larve were collected, most of the smaller
ones were left among the buds. On May 29 the field received a
second irrigation. The larve at this time were very abundant; the
gathering machine, too, had retarded the growth of the plants by
breaking off the growing tips and some of the plants themselves had
been broken down by the collecting machine. As a result the alfalfa
had apparently made little or no growth since about the 22d, and its
value as forage was at that time rapidly decreasing. |
A wire-brush machine (PI. VI, fig. 1) was constructed by Mr. L.
Hemenway by bolting about 30 pieces of No. 8 steel wire 7 inches
long between iron clamps on each spring tooth of an old spring-tooth
cultivator. The ground was gone over with one of these on June 1,
as soon as the hay had been removed. The jumping action of the
spring, together with the wire brushes, proved very effective in crush-
ing larve and pupe among the stubble. The field was then gone
over with a plank leveler, shown in Plate VIII, figure 2, with square
iron edges bolted to a plank. June 7, the field received another
brushing with the wire-brush machine, which crushed cocoons and
larve. By June 13 the second crop in this field had started nicely
with very few weevils present. In another field near by no attempt
had been made to treat it or to remove the weevil, and this field was
taken as a check on the one under treatment. An examination at
this time showed that when the former field was in good condition,
with few larve, the field that had received no treatment was bare
and brown from their attack.
On June 22 the second crop of alfalfa on the treated field was about
8 inches high, while the unworked field was still bare and its condi-
tion, on June 27, is shown in Plate VI, figure 3. By the 27th the
alfalfa in the treated field was about 1 foot in height (see Pl. V1,
fig. 2), the stand extra good, and the treatment had seemed to free
the field from weeds and other foreign growth. By July 7 the plants
were about 2 feet in height, while, of course, both the adults and
larve could be found to some extent in this field. July 27 the second
crop harvested 2 tons per acre, selling at $9 per ton in the field. The
field at time of harvest of second crop is illustrated in Plate VII,
figure1. The unworked field, however, was making an inferior second
crop, coming just a little in advance of the third crop in the treated
field.
From the treated field there was also a fourth crop of hay secured.
The field was photographed on October 9, 1911, and the yield of hay
is illustrated in Plate VII, figure 2. The condition of the check field
a few days later, October 12, is shown in Plate VII, figure 3; here the
second and third crops were both not only badly damaged, but so
delayed in growth of alfalfa that, as shown by the illustration, no
fourth crop was secured at all.
Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PreATE Ve
Fic. 1.—Street sweeper in operation on alfalfa field after first crop was removed. Larve and pup
were crushed by the rotary brush. Photographed June 14, 1911. (Original.)
Fie. 2.—Second crop ready to cut in the field on which street sweeper was used June 14, 1911. Good
stand and good crop. Photographed July 27,1911. (Original.)
ar
©
x Le
Fic. 3.—Second crop of alfalfa growing on field where no treatment was given. Crop short and about
two weeks behind that of the field shown in figure 2. Photographed July 27,1911. (Original.)
FIELD EXPERIMENTS AGAINST THE ALFALFA WEEVIL.
Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE VI.
Fig. 1.—Wire-brush cultivator in operation on alfalfa field after first crop wasremoved. ‘The brushes
crush the larve and pupe on the ground at this time. Photographed June 7, 1911. (Original.)
Fic. 2.—Second crop of alfalfa growing nicely as a result of treatment given. (See fig. 1, above.)
Larve and pup2 were killed, so that second crop suffered only slight injury. (Original.)
Fic. 3.—Condition of untreated fields about June. Photographed June 27,1911. (Original.)
FIELD EXPERIMENTS AGAINST THE ALFALFA WEEVIL.
Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE VII.
Fig. 1.—Second crop of alfalfa, estimated at 2 tons per acre, secured from field treated with wire-
brush cultivator. Photographed August 2, 1911. (Original.)
Fie. 2.—Fourth crop of alfalfa secured from field where brush cultivator was used. Photographed
October 9, 1911. (Original.) :
Fic. 3.—Condition of field used as check (PI. V, fig. 3). The second and third crops on this field
made little growth and were much delayed, so what would correspond to the fourth crop was
caught by frost. Photographed October 12,1911. (Original.)
FIELD EXPERIMENTS AGAINST THE ALFALFA WEEVIL.
Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE VIII
Fic. 1.—Alfalfa field after first crop was removed, severely disked preparatory to application of
“‘mudding”’ process against the alfalfa weevil. Photographed June 21, 1911. (Original.)
antes
PO
Fic. 2. Following the irrigation water with a drag, to ‘“‘ puddle”’ the weevils in the mud.
Photographed June 22, 1911.
FIELD EXPERIMENTS AGAINST THE ALFALFA WEEVIL.
Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE IX.
Fic. 1.—Second crop of alfalfa in field treated by ‘‘mudding”’ process. Crop growing well and not iit
seriously damaged by the alfalfa weevil. Photographed June 10, 1911. (Original.) |
Fic. 2.—Condition of untreated fields at time photograph shown in figure 1 was taken. The
alfalfa weevils have prevented the second crop from starting. Photograph taken July 10,
1911. (Original.)
ss
Fic. 3.—Patch of first crop left in field shown in figure 1, illustrating how the larvee were dissem-
inated from the first crop into the field where the weevil had been killed by the ‘‘ mudding”’
process. Photograph taken July 10, 1911. (Original.)
FIELD EXPERIMENTS AGAINST THE ALFALFA WEEVIL.
FIELD EXPERIMENTS IN DESTROYING WEEVIL. 29
CULTIVATION IN CONNECTION WITH IRRIGATION.
For an experiment to determine the value of cultivation in connec-
tion with irrigation in controlling the alfalfa weevil a field was selected
on a farm belonging to Mr. Hansen, 1 mile southeast of Sandy,
Utah, containing 16 acres. The soil was a light sandy loam. Some
of the weevils had been noticed in this field in 1908 and also in 1909,
while the first crop of 1910 was severely damaged and the second also
suffered considerable loss. May 11, 1911, the field was irrigated, the
infestation being considered heavy. The first crop was cut during
the week ending June 10. The plants were about 9 or 10 inches high
and the hay yielded less than 1 ton per acre of very poor quality.
This field was again irrigated and the more elevated portion of it
worked with a spring-tooth harrow while the surface was still soft
from the irrigation. This treatment was repeated and when finished
the field had very much the appearance of any cultivated field,
little resembling a meadow. (See Pl. VIII, fig. 1.)
On June 22, while the land was still soft and muddy, a light irriga-
tion was given it, so that the water collecting in the lower portion of
the field stood to a depth of 2 or 3 inches. Four horses were hitched
to a plank leveler and dragged through this mud, as shown in Plate
VIII, figure 2. This thoroughly ‘‘puddled” the weevil in all of its
stages beneath the surface.
By the 30th of June a second crop was starting very nicely while
neighboring untreated fields were being retarded by the continued
attacks of the weevil. Ten days later the plants were about 12
inches high with very few of either larvee or beetles present. How-
ever, a patch had been left uncut and unworked in one corner of this
field and here the first crop of alfalfa was still standing. (See PI.
‘IX, fig. 3, at the right.)
There were a great many larve and beetles on this patch, which
disseminated themselves into the growing alfalfa where the mudding
process had been practiced, destroying a strip about 1 rod in width,
clearly shown in Plate IX, figure 3. The second crop in this field,
July 10, 18 days after the mudding experiment was carried out, was
about 14 inches high. (See Pl. IX, fig. 1.)
In a near-by untreated field at ‘ihe same time, four weeks after the
first cutting was made, the condition is ‘shown in Plate IX, figure 2.
~ Burninea MACHINE.
Several field experiments were carried out with a machine con-
structed with the idea of burning over alfalfa fields after the removal
of the first crop for the purpose of destroying the weevils in any stage
of development remaining in the field. The machine, as shown in
Plate X, figure 1, consisted of an iron frame 9 feet square, 12 inches
30 PRELIMINARY REPORT ON ALFALFA WEEVIL.
high in front, and adjustable in the rear. The top was of light sheet
iron bolted to the frame.
Oil was pumped from a barrel in the conveyance to which this
machine was attached and forced through a rubber hose into a supply
pipe which fed the nozzles and burners underneath. The oil under
pressure came forth from the burners as a mist of fire blowing into the
stubble and against the ground.
The ene cover served to hold the heat se while this oven
passed slowly over the surface. In its unperfected state the machine
did effective work and offered ideas of value, warranting the construc-
tion of more efficient burners.
In fields where there was a clean stand of alfalfa stubble this
machine did very well in burning vegetation and destroying all insect
life above the surface of the ground. Where many weeds, especially
dandelions, were present, the insects found protection under the green
leaves. Where parts of fields were burned over, the unburned area
showed no growth for several weeks on account of the continued
weevil attack. The burned area turned green within a very much
shorter time.
REDUCTION IN QUALITY OF HAY CAUSED BY THE ALFALFA
WEEVIL.
While studying the alfalfa weevil on various farms in the Salt Lake
Valley during the month of April, 1911, it was found that many farm-
ers, through a shortage of forage, were feeding the weevil-injured
hay of the first crop to their horses. This hay contained so many
old cocoons and was so dusty from larval excrement and dead bodies
of weevil larve as to render it unfit as feed for horses. On several
occasions horses were observed coughing from the effect of this dust.
In fact, many farmers consider the first crop from severely infested
fields almost valueless as horse feed.
On June 12, 1911, at Alpine, Utah, when the new hay from the first
crop was fed to work horses these began coughing almost immediately
after starting to feed upon this injured hay. The hay contained
large numbers of dead weevil larve, some still on the skeletonized
leaves and some in the freshly spun cocoons. On September 13 hay
from the first crop, in stack’, was examined at Layton, Utah, and
found to be very dusty, containing many dead weevil larvee and also
pupe.
NATURAL ENEMIES.
The natural enemies of the alfalfa weevil consist of vertebrates and
invertebrates. The former have been studied by assistants of the
Bureau of Biological Survey, and a list of species observed to attack
the weevil is given herewith.
NATURAL ENEMIES. — oo oe
The invertebrate enemies are divided between native species and
those imported from Italy, the native being largely predaceous and
the foreign all parasitic.
Besides these, there are two fungous enemies, both of which affect
the insect to a greater or less degree.
INVERTEBRATES.
When a foreign species, like the alfalfa weevil, is introduced into a
new country, some time is required for the native insects to find out
that it is suitable for food, pre-
cisely as man himself would
under the same circumstances
have to learn what products
of a new country were edible.
Besides, he would most likely
cultivate a taste for some of
these things which at first were
distasteful to him. Thus it is
that native insect foes of in-
troduced species begin. slowly Fia. 9.—Nine-spotted lady-beetie (Coccinella 9-notata):
at first to prey upon them. a, Adult; b, lerva. Much enlarged. (From Chit-
The following native pre- “"*"? |
daceous insects have been found attacking and devouring the alfalfa
weevil:
PREDACEOUS ENEMIES.
A species of tiger-beetles,-Cicindela imperfecta Lec., was in one
instance observed to feed upon an alfalfa weevil larva in the field.
Several other indi-
viduals belonging
to the same species
when taken to the
laboratory readily
devoured larve.
Three species of
lady-beetles, Coc-
cinella 9-notata,
Hbst. (fig. 9), Hip-
podama spurra
Fig. 10.—Convergent lady-beetle (Hippodamia convergens): a, Adult; b, Lee a and H. con-
pupa; c, larva. Enlarged. (From Chittenden.) b
vergens Guér.
(fig. 10), in the larval stage attacked and devoured half-grown larvee
of the alfalfa weevil in the fields. Larve so taken were brought into
the laboratory and adults reared, from which specific determina-
tions were made. In case of H. spuria the adult was also observed
devouring larve in the field.
The malachid beetle, Collops bipunctatus (fig. 11), was repeatedly
observed feeding upon the weevil larve in the fields.
32 PRELIMINARY REPORT ON ALFALFA WEEVIL.
The tenebrionid beetle, Eleodes suleipennis Mann., was accused by
farmers of feeding upon the larve of the weevil and when taken to
Fic. 11.—The two-spotted Collops ( Collops bipunciatus): Adult.
Enlarged. (Origmal.)
the laboratory it readily
did this in confinement.
An allied species, E.
suturalis Say, was ob-
served by Mr. E. O. G.
Kelly to devour chinch
bugs in the_ neighborhood |
of Wellington, Kans. In
the latter imstance the
beetles seemed to prefer
the partially decaying
leaves of corn under
which the chinch bugs
were hiding. It is prob-
able that while these in-
sects may devour a few of
the weevil larve theyprefer
other and vegetable food.
The predaceous mite, Pediculoides ventricosus Newp. (figs. 12, 13),
was introduced from Indiana in March, 1911, but was afterwards
Fic. 12.—Pediculoides ventricosus,
@ mite predatory on the alfalfa
weevil: Adult female before the
abdomen has become inflated
with eggs and young. In this
condition the mite is nomadic
and predatory. Greatly en- Fic. 13.—Pediculoides ventricosus: Adult female after the
larged. (Redrawn from abdomen has become inflated with eggs and young.
Brucker.) Greatly enlarged. (Redrawn from Brucker.)
found a sufficient distance away from the points of introduction to
show plainly that it was already an inhabitant of Utah. The results
Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PUATE
Fic. 1.—BURNING MACHINE EXPERIMENTED WITH AS A METHOD OF DESTROYING
THE ALFALFA WEEVIL. (ORIGINAL.)
Fia. 2.—BOXES CONTAINING PARASITES OF THE LARVA AND PUPA OF THE
ALFALFA WEEVIL, SHOWING HOW THIS MATERIAL WAS IMPORTED INTO THE
UNITED STATES FROM ITALY. PHOTOGRAPH TAKEN JUNE, 1911. (ORIGINAL.)
Fig. 3.—BoOXES OF PARASITE MATERIAL IMPORTED FROM ITALY WHICH CONTAIN
E@a@ PARASITES OF THE ALFALFA WEEVIL. PHOTOGRAPH TAKEN MAy, 1911.
(ORIGINAL.)
NATURAL ENEMIES. 38
wai experiments with this mite, which is so effective in destroying the
jointworm in the East, were unsuccessful, as it was found that the
mites would not attack either the larve or the pupz. They fed
freely upon the eggs of the weevil, where these were easily accessible,
but they seemed unable to gain access into many of the egg masses
through the ordinary egg punctures. A single egg did not furnish
sufficient food to bring
one mite to maturity,
and it would therefore
necessarily perish; but
where there were clus-
ters of eggs in contact
- with each other, the
female mite was able to
shift her body about
sufficiently to devour
more than one egg and
was thus enabled to
reproduce. Inthefield,
when placed in cages
with an abundance of
eges of the alfalfa wee-
vil, the mites appeared
to make considerable
headway in overcoming
the weevil, butin no case
could the effects of their
attack be traced farther
>)
\
than 2 feet from the cage )
where they ha d b een Fia. 14.—A predaceous mite, Erythreus arvensis: Adult. Greatly
confined in the fields | ee eee
_ A little mite (Trombidium) was found attached to the adult weevil
beneath the wing covers, and while it was observed quite commonly
in late summer and fall, so far as observations indicated it did not
appear able to kill the host insect. A predaceous mite, Hrythreus
arvensis Banks (fig. 14), was found, by Mr. Ainslie feeding on eggs of
the weevil in the egg punctures. The economic value of this species
is as yet very obscure. Spiders are occasionally found feeding upon
the larve in the fields. Lace-wing flies (Chrysopa) fed upon the
larve in confinement when forced to do so, but preferred aphides.
They were not observed to attack the weevil in any form in the fields.
~ 26200°—Bull. 112—12-—_3
34 PRELIMINARY REPORT ON ALFALFA WEEVIL.
A NATIVE TRUE PARASITE.
Only one specimen of a single species of 2 true parasite of the alfalfa
weevil has so far been found in America. This was described by
Mr. Viereck as Znoplegimorpha phytonomi. It was found August 30,
1911, at Hoytsville, Utah, in the form of a cocooned pupa within the
cocoon of the alfalfa weevil. The specimen was picked up from the
surface of the ground in a badly infested alfalfa field and the adult
parasite reared. The adult emerged September 3.
INTRODUCED PARASITES.
Several species of parasites were sent over from the vicinity of
Portici, Italy, by Mr. W. F. Fiske during April, May, and June, 1911.
Fig. 15.—Anaphes sp., 2 mymarid egg parasite of the alfalfa weevil: Adult male; female antenna above
at right. Greatly enlarged. (Original.)
The egg parasites were obtained by collecting stems of alfalfa con-
taining eggs of the alfalfa weevil, placing these in boxes (Pl. X, fig. 3),
and transporting them by cold storage on steamers bound for New
York. On arrival from Europe they were promptly forwarded by
.
,
;
al
4
|
refrigerator express to their destination, Salt Lake City, Utah, where |
they were at once taken either to the laboratory at Salt Lake City
(Pl. XIII, fig. 1) or to the laboratory at Murray (Pl. XIII, fig. 2).
Parasites that attack the weevil after it has hatched and before it
has developed to the adult were handled in much the same manner. ~
The boxes in which they, were consigned are shown in Plate X, figure
2. The time required to transport these boxes from Portici, Italy,
to Salt Lake City, Utah, was from 16 to 21 days.
NATURAL ENEMIES. 35
Ecc PARASITES.
There were two ege parasites, one, a true egg parasite developing
within the egg, and the second, a parasite the eggs of which are prob-
ably deposited in the alfalfa stems among, but not in, the eggs. The
larva of the latter is predaceous on the masses of weevil eggs as placed
by the female weevil, and among them it develops to the adult.
MYMARID EGG PARASITE.
A mymarid egg parasite, Anaphes sp. (fig. 15), was found in all
of the seven shipments received from Italy. It was received in all
stages of development, except perhaps the egg and adult, and was
either left in the same aa these being perforated with holes and
Fig. 16.—Imported pteromalid egg parasite of the alfalfa weevil: Adult. Greatly enlarged. (Original.)
glass tubes inserted (Pl. XI, fig. 2), or placed in specially prepared
-boxes (Pl. XI, fig. 3) which were also perforated and had glass tubes
inserted. The parasites were reared from this imported material,
and from the parent stock two generations were reared on American
egg masses of the alfalfa weevil. The third generation, together with
others of the first and second generations and natives from later ship-
ments, was placed in field reproduction cages (Pl. XII, fig. 3) to
the number of about 300. These cages were overstocked with eggs
by confining numbers of weevils in them. After about 10 days the
covers to these cages were removed, thus allowing the generation of
parasites that developed within Gen to escape and scatter freely
over the fields. MH
PTEROMALID EGG PARASITE.
A pteromalid egg parasite (fig. 16) was likewise found in all of the
seven importations. The larva (fig. 17) feeds externally on the egg
masses in the alfalfa stems, later transforming to the pupa (fig. 18).
36 PRELIMINARY REPORT ON ALFALFA WEEVIL.
The disposal and management of this species did not differ from that
followed with the preceding, except that some of them were received
too late in the season to use in the low valleys because the majority
of the eggs of the weevil had already hatched. Owing to this the
parasites were taken to places in higher elevations
where eggs of Phytonomus were still abundant.
Approximately 460 were placed in field cages like
those previously mentioned and treated’ in the
same Way.
controlling the alfalfa weevil in Italy.
PaRASITES OF LaRv& AND Pup.
The parasites of the larve and pupe of the alfalfa
weevil, which were five in number, did not appear in
ee ha esa eg ee aries consignments. from Italy and were confined
pteromalid egg to the last three received at Salt Lake City May 16
parasite of the
alfalfa ,weevil.
Greatlyenlarged. boxes (Pl. X, fig. 2), which included only the cocoons
ba of the alfalfa weevil. These boxes were especially
devised to guard against the accidental Paes of adult insects of
any species en route.
After being removed from the boxes in which the cocoons were
received, they were placed in parasite boxes of the larger type
(Pl. XI, fig. 3), where the parasites emerged and were
separated from the weevils that had developed en route.
Both weevils and parasites on emerging from the cocoons
in the box would seek the hght and appear in the glass
tubes shown in the illustration, where they were readily
separated and the weevils killed. The parasites were.
then transferred to glass cages (Pl. XI, figs. 1, 4) which
had been previously well stocked with larve and cocoons.
PTEROMALID LARVAL PARASITE.
A pteromalid parasite of alfalfa weevil larve (fig. 19,
female; fig. 20, male) was received in only the later m6 13—pPupa
consignments. ‘Thus far it has not been possible to deter- of Ptero-
mine the species. In the laboratory rearings, preparatory pea § a
to placing the parasites in the field cages, and later, the the alfalfa
species was carried through five generations. (Fig. 21, a Gineatiy sch
shows the pupa of the alfalfa weevil, with the egg (fig. 21, 5) eae :
asit is placed on the pupa; fig. 22 shows the larva, and fig.
23 shows it destroying the pupa of the alfalfa weevil; fig. 24 shows the
pupa of the parasite itself.) In order to accomplish this, however, it
was necessary to secure weevil larve, as hosts for them, from high
Mr. Fiske found this species to be very éffectieta in
to June 3. In these three shipments were metal
.
:
Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE Xl.
Figs. 1 and 4.—Types of cages in which larval and pupal parasites of the alfalfa weevil were
reared in the laboratory. Photograph taken during June, 1911. (Original.)
Figs. 2 and 3.—Boxes sealed and fitted with glass tubes into which imported parasites emerged and
were separated in the laboratory. Photograph taken during May and June, 1911. (Original.)
INTRODUCTION OF PARASITES OF THE ALFALFA WEEVIL.
Bul. 112, Bureau of Entomology, U. S. Depi. of Agriculture. PLATE XIl.
Fics. 1 AND 2.—FiIELD CAGES USED IN HIBERNATION EXPERIMENTS ON THE ALFALFA
WEEVIL. (ORIGINAL.)
Fig. 3.—PLANTING A COLONY OF IMPORTED PARASITES OF THE ALFALFA WEEVIL
IN UTAH IN AN ALFALFA FIELD. PHOTOGRAPH TAKEN DURING JUNE, 1911.
(ORIGINAL. )
NATURAL ENEMIES. 37
elevations and bring these into the laboratory, thus supplying them
artificially. There were 230 individuals liberated in field cages, the
coverings of which were later removed, and 49 liberated directly
Fig. 19.—Pteromalid parasite of larva and pupa of the alfalfa weevil: Adult female. Greatly enlarged.
(Original.)
4
%4
a
Y
Fig. 20.—Pteromalid parasite of larva and pupa of the alfalfa weevil: Adult male. Greatly enlarged,
} (Original. )
into the open field. Observations have since shown that this species
has actually colonized itself in the field ; whether temporarily or per-
manently it remains to be seen.
38 PRELIMINARY REPORT ON ALFALFA WEEVIL.
OTHER PARASITES.
The following three parasites came mainly in the last two shipments
from Italy. The adult of one species (Canidiella curculionis Thoms.)
(fig. 25) oviposits in the larvee of the alfalfa weevil in different stages
of development, but the offspring therefrom
emerge from the
cocoon spun by the
weevil, the cocoons
of the parasite always
showing through the
meshes of the cocoon
of the weevil (see fig.
27). 'Thisspecieshas
two generations an-
nually and hibernates
as cocooned larve.
The alfalfa stems
Fic. 21.—Pteromalid parasite of larva from which thethree FG. 22.—Pteromalid parasite
and pupa of the alfalfa weevil: a, Sige f “e of larva and pupa of the
Enlarged pupa of alfalfa weevil with species O parasites alfalfa weevil: Larva.
eggs of parasite in place; b, egg, of this eroup were Greatly enlarged. (Orig-
greatly enlarged. (Original.) inal.)
reared were also in-
fested by Apion pisi Fab., and therefore some or all of the group may
perhaps also parasitize this latter insect. Owing to its small size,
however, as compared to the parasites, this seems rather unlikely-
The two additional species reared with the preceding
are not definitely determinable, but
one is Phygadewon sp., and the
other may prove to be Mesochorus
migripes Ratz. Of this latter spe-
cies Mr. T. W. Wassiljew, a Russian
entomologist, under date of Febru-
ary 6, 1911, wrote us:
I wish to say that I am able to give you
only one instance of a parasite having been
found, and that was in the vicinity of Tasch-
kent (Turkestan), where I noticed in the
past year [1910] that over 20 per cent of the
larvee of P. variabilis were attacked by an
: < Fia. pars of
Fic. 23.—Larva of ptero- Ichneumon parasite. Unfortunately I do pteromalid para-
malid parasite attack- not know the name of this species of para- __ site shown in fig-
~ oie pi samy site at the present time, other than thatit be- ures 22 and 23.
(Original.) ee Jongs to the Ichneumonide. Judging from Oceana
the elliptical, thick-shelled cocoon it might :
possibly have been Mesochorus nigripes Ratz., which Mr. Ratzeburg (The Ichneu-
monide, III, p. 120) gives as a parasite of P. rumicus.
All of these parasites resemble each other to a certain degree, al
figure 25 will suffice to illustrate them, for the present at least. At
the present stage of this experiment in introducing parasites of the
jail a al al
Pe a
. » =
NATURAL ENEMIES. 39
alfalfa weevil the possibility of permanent establishment and future
efficiency in the case of these species seems rather more encourag-
ing than in case of the others. During June, 1911, 40 individuals
reared from imported cocoons were placed in field cages artificially
overstocked with weevil larve, the cage covers being removed later.
Besides this, there is at present on hand a considerable amount of
hibernating material (Pl. XII, figs. 1, 2) artificially reared in the
Murray laboratory (Pl. XIII, i= 2), ie will be allowed to eo
naturally, into the alfalfa falda,
Fig. 25.— Canidiella curculionis, a parasite of the alfalfa weevil: Adult female; lateral view of abdomen
of same below, at right. Enlarged. (Original.)
The parasite Itoplectis masculator Fab. (fig. 26) differs from the
preceding by reason of the fact that it pupates entirely within the
pupa of its host. It is known to be a primary parasite, but the num-
ber so far secured is too limited to warrant any discussion regarding
it, or any predictions as to its future in America.
Of the eighth and last of these parasites, Hemiteles sp., very little
isknown either in Europe or America, and with the obscurity surround-
ing its habits it may prove to be either a primary or secondary
parasite, a friend or an enemy of the others. It is therefore being
handled with the utmost caution, none having been liberated either
in the fields or in field cages.
40 PRELIMINARY REPORT ON ALFALFA WEEVIL.
VERTEBRATES.
During the season of 1911 the Biological Survey, at the suggestion
of the writer, kindly detailed an assistant, Mr. E. R. Kalmbach, to
study the bird and other vertebrate enemies of the alfalfa weevil, ©
and the following is a list of vertebrates found to feed on the alfalfa
weevil in Utah, as determined by Mr. Kalmbach, May 7, 1911, to
July 25, 1911.
Wilson’s phalarope, Steganopus tricolor; kKilldeer, Oxyechus vociferus; valley quail,
Lophortyx californica vallicola; mourning dove, Zenaidura macroura carolinensis; red-
shafted flicker, Colaptes cafer collaris; Arkansas kingbird, Tyrannus verticalis; Say’s
Fic. 26.—Itoplectis masculator, a parasite of the alfalfa weevil: Adult female; lateral view of first abdominal
segment at right. Muchenlarged. (Original.)
phoebe, Sayornis sayus; Traill’s flycatcher, Empidonax trailli; desert horned lark,
Otocoris alpestris leucolema; magpie, Pica pica hudsonia; bobolink, Dolichonyx oryzi-
vorus; cowbird, Molothrus ater; yellow-headed blackbird, Xanthocephalus xantho-
cephalus; thick-billed red-winged blackbird, Agelaius pheniceus fortis; Western mead-
owlark, Sturnella neglecta; Bullock’s oriole, Icterus bullocki; Brewer’s blackbird,
Euphagus cyanocephalus; house finch, Carpodacus mexicanus frontalis; English sparrow,
Passer domesticus; Western vesper sparrow, Powcetes gramineus confinis; Western
savannah sparrow, Passerculus savannarum alaudinus; Western lark sparrow, Chon-
destes grammacus strigatus; white-throated sparrow, Zonotrichia albicollis; Brewer’s
sparrow, Spizella breweri; Western chipping sparrow, Spizella socialis arizonx; desert
song sparrow, Melospiza melodia fallax; green-tailed towhee, Oreospiza chlorura; black-
Bul. 112, Bureau of Entomology, U. S. Dept. of Agriculture. PLATE XIII.
Fias. 1 AND 2.—LABORATORIES OF THE BUREAU OF ENTOMOLOGY, U. S. DE-
PARTMENT OF AGRICULTURE, AT SALT LAKE CITY AND Murray, UTAH.
(ORIGINAL. )
NATURAL ENEMIES. Al
headed grosbeak, Zamelodia melanocephala; rough-winged swallow, Stelgidopteryx
serripennis; sage thrasher, Oreoscoptes montanus; Western robin, Planesticus migratorius
-propinquus; Rocky Mountain toad, Bufo lentiginosus woodhousi; leopard frog, Rana
pipiens; salamander, Amblystoma sp.
Funcous ENEMIES.
‘Whenever the larger species Hypera punctata (fig. 2) becomes
excessively abundant east of the Mississippi River, myriads of
these larve may be observed coiled about
the uppermost tip of blades of grass or
similar vegetation, where they soon die and
become black. These are apparently de-
stroyed by afungus, Empusa spherosperma.
When investigations of the alfalfa weevil
were first undertaken there were great
numbers of these dead and dying larve to
Paoumndan Washington, D.C.,in Potomac. y¢ 27 cocoon of the alfalfa weovil
Park. They were gathered up and sent showing cocoon of the parasite
out to Salt Lake City and placed in the Paine MA THs Dro rs.
hands of Mr. Ainslie with the hope of in- -
- troducing this fungus among the larve of the alfalfa weevil. The
experiment appeared to have been a failure, and it was thought
that the climate of Utah was too dry to enable this fungus to
exist there. Later this larger species was found in Utah, as has
already been stated, and during the spring of 1911 the fungus
was found in the vicinity of Salt Lake City. Apparently, how-—
ever, the fungus does not affect the larve to the same extent
that it does here in the East, except after these have -reached
their full size and constructed their cocoons. Larve of the alfalfa
weevil (fig. 5) and pupe (fig. 7) soon began to be observed in the
cocoon (fig. 6) dead and thoroughly permeated: with this fungus.
No individuals in any case were found dead excepting within their
cocoons. On June 13 in the vicinity of Salt Lake City it was
estimated that one-fifth of the cocoons contained dead larve or
pup. In the Weber Valley, about Hoytsville, Utah,:on the last
of August, it was found that of 580 cocoons examined 258, or 44.5
per cent, were dead, partly at least because of infestation by this
fungus. Examination at another point showed that 38 per cent had
apparently died from the same cause. To all appearances, then, this
was more effective in killing the alfalfa weevil than all other natural
enemies combined.
NN ——— ———————Eee ee —_—
Pe
INDEX
Page
Ainoplegimor pha phytonomt, parasite of alfalfa weevil...............------- At 34
Agelatus pheniceus fortis, enemy of alfalfa weevil.......2....---..-.--+-----: 40
Alialia (see also Medicago sativa).
duration of growing which should be allowed in weevil-infested districts. 12
meer ior aileal ey weevil 22% 2:2 tes We eR yee a esse ss Bee sed. 2 1-41
clover-leaf weevil (Hypera punctata).......------------- 15
hay, reduction in quality caused by alfalfa weevil.........---.------- 30
varieties experimented with in relation to alfalfa weevil.--....-..--..-- 14
Beeeslagitl). Gescription and habits: ..--.<-.. 2:22.22. 52502 11-12, 15-17
alhiedispecies miroduced trom Kurope.: :.ss..222..2.22.2..2. Pe vic,
fopeatanee of second speeres im Utah. .: 2.52.2 .2s- 222 425----- 15
Cmte BORER CRiO LGM Co 08 0 wee Fase Pais oo le Hens 2 hls 12
Seem Ane TOURING. =o sl Se ei 2d ee. aio deed see 23-28
cooperation of Bureau of Entomdlogy and Utah Experiment
eyepiece ee Ree ie Fo alos AIL a at 12-14
with other bureaus of U. 8. Department of Agricul-
PME Cee ena se AS ees te oe Seta toe de tes 14-15
Doserimdan and ceasonak history: Jace Piliae de. 2- 2s 25 2. 222% 2% 15-24
Sea ipRa sei RE re tr Es oi. 8 ot te eis ae es bs el 25-26
Semioninoneim- the old: world). 4.2 ..ee8.sse8.edebeseiail: 9
Pare ea ee ae sete IO We. eee Beeb waited ties 12, 17-19
Anne ETO, . ys
: Page.
Medicrgo lupulina, experiment against alfalfa weevil. ..... ....2 2a 7m
food plant of alfalia weevil... 20S. 8_.:2..:.._ 23 24
muricaia, experiment against alialfa weevil.--...:..........J222 eee 14
food plant of alfalfa weevil.........--- gn s2 2... a
orbicularis, experiment against alfalfa weevil....................... Sm
food plant of alfalfa weevil...........), 2) ee 24
ruthenica, experiment against alfalfa weevil. ......................- 14
sativa (see also Alfalfa).
experiment against alfalfa weevil...-.........-..). ee 14
scutellata, experiment against alfalfa weevil...........-....--22ueeee 14
food. plant. of alfalfa, weevil....<.<..-.... +] 23 24
Melilotus alba, fqgod plant of alfalfa weevil...............:-..-..55- 550 24
indica, food plant of alialia weevils. ..2.--.55.2225e. = eee 4. ee 24
Melospiza melodia fallax, enemy of alfalfa weevil......:.....------.225+.eseeee 40
Mesochorus nigripes, parasite of alfalfa weevil....................-.------ eis 38
Phytonomus rumacis. : . ...-202+.--222 eee 2 38
Molothrus ater, enemy of alfalfa weevil..............-.------ ee 40
Oreoscoptes montanus, enemy of alfalfa weevil. -.:.......:-.---.225332==eeee 40
Oreospiza chlorura, enemy of alfalia weevil....-.....:..2-.-2.-.>. 525 40
Oriole, Bullock’s. (See Icterus bullock.)
Oiocoris alpestris leucolema, enemy oi alialia weevil.........-..-.-7 =e 40
Oxyechus vociferus, enemy of alfalfa weevil..-..........--.-..+-)250.==e 40
Passerculus savannarum alaudinus, enemy of alfalfa weevil.............-..--.-- 40
Passer domesticus, enemy of alfalia weevil....-.....--...---2.--s=)==eeeeee 40
Pea, chick, eaten by alfalfa weevil..........---22---:.:5==——n 38
Physalis longifolia refused as food by alfalfa weevil. .............253.===eeae 24
Phytonomus murinus, name incorrectly applied to alfalfa weevil......-......- 15
nigrirosiris, introduction into United States... -...-.- 253 .ueueeeee 9
posticus. (Sce Alfalia weevil.)
punctatus (see also Hypera punctata).
punctatus Hypera punctata....-. ---- c= =~. + ==) = 25 it
introduction into United States ....::. .. 33a 9
rumicis, host of Mesochorus nigripes..-----<+22- +--+ =5se en 38
variabilis, name given alfalfa weevil in old world. ......--------- 15
Pica pica hudsonia, enemy of alfalfa weevil.....--.--------:-::=-25===e 40
Pigweed, rough. (See Amaranthus retroflexus.)
Pisum sativum refused as food by alfalfa weevil............------------++---> 24
Planesticus migratorius propinquus, enemy of alfalfa weevil. .....------------ 40
Polygonum aviculare refused as food by alfalfa-weevil.....------------------- 24
Powcetes gramineus confinis, enemy of alfalfa weevil.......----.------------- 40
Portulaca oleracea refused as food plant by alfalfa weevil. .......------------- 24
Pteromalid egg parasite of alfalfa weevil.......-.....----------+---------+---: 35-36
larval parasite of alfalfa weevil......---.---2-+---+0::-----===—ee 36-37
Purslane. (See Portulaca oleracea.)
Quail, valley. (See Lophortyx californica vallicola.)
40
INDEX.
Robinia pseudacacia, food plant of Sigal weevil av: ese, eee
Robin, western. (See Planesticus migratorius propinquus.)
Salamander. (See Amblystoma sp.)
Sayornis sayus, enemy of alfalfa weevil......... ee se FO ie ed
Sheep, pasturing as remedy against alfalfa weevil. ..........-..-..---
Sparrow, Brewer’s. (See Spizella brewer.)
desert song. (See Melospiza melodia fallax.)
English. (See Passer domesticus.)
western chipping. (See Spizella socialis arizon2.)
lark. (See Chondestes grammacus strigatus.)
savannah. (See Passerculus savannarum alaudinus.)
vesper. (See Poewcetes gramineus confinis.)
white-throated. (See Zonotrichia albicollis.)
Spider plant. (See Cleome serrulata.)
pauaerwememes Of alfalia weevil..........-.2---..+-s22+-+--++-e 5-5
pela brewer, enemy of alialia weevil............-.2..2---.2.-- oe
socialis arizonx, enemy of alfalfa weevil..........-...-.-.-----
Dieganopus tricolor, enemy of alialfa weevil. .........--.-..-.---.-----
Stelgidopteryx serrupennis, enemy of alfalfa weevil..............-----.-
Siurnella neglecta, enemy of alfalia weevil.......--...--------.--.-.---
Swallow, rough-winged. (See Stelgidopteryx serripennis.)
pweeper, street, against alfalfa weevil..........-.-+.../----.-.+------
Sweet pea. (See Lathyrus odoratus.)
Thrasher, sage. (See Oreoscoptes montanus.)
Toad, Rocky Mountain. (See Bufo lentiginosus woodhouset.)
Towhee, green-tailed. (See Oreospiza chlorura.)
Trifolium hybridum, food plant of alfalia weevil.................--..--
prearense. 4000 plant of alfalfa, weevil......7-..0..-......-+4-
repens, food plant of alfalfa weevil. .......-.-- SE Oe aa oe
Trigonella fenumgrxecum, food plant of alfalfa weevil......-........-.--
iirannus verticals, enemy of alialia weevil. ........--.-.----.-.....--
Vetch, hairy or winter. (See Vicia villosa.)
narrow-leaved. (See Vicia sp.)
obtuse-leaved. (See Vicia sp.)
spring. (See Vicia sativa alba.)
Utah milk. (See Astragalus utahensis.)
Vicia atropurpurea eaten by alfalfa weevil...............-.. “a SERN ete
Maeno eauen by aitalia weevil. 2.2. ..32-.0.-.-..2550s51-ese---
mamaiooeeaten by alfalfa weevil. ...-...:..:....-..-..s-------
peed plat of alialia weevil.....0......2..+-52.-+--+-+--4-2-
fmmentem by alfalia weeval..--....22.-2..5/2.-225--4-20 nse
Weevil, alfalfa. (See Alfalfa weevil.) _
Wilson’s phalarope. (See Steganopus tricolor.)
imwomen aeainstalialia weevil........--2.-.-.-.0....-. cece eee n eee
Xanthocephalus xanthocephalus, enemy of alfalfa weevil.......
Zamelodia melanocephala, enemy of alfalia weevil............-.....---
Zenaidura macroura carolinensis, enemy of alfalfa weevil. ..........---
Zonoirichia albicollis, enemy of alfalfa weevil...............-.-..----
O
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