Comments and suggestions on locust control in Argentina

Material Information

Comments and suggestions on locust control in Argentina
Parker, J. R
United States -- Bureau of Entomology and Plant Quarantine
Place of Publication:
[Washington, D.C
U.S. Department of Agriculture, Agricultural Research Administration, Bureau of Entomology and Plant Quarantine
Publication Date:
Physical Description:
14 p. : ; 27 cm.


Subjects / Keywords:
Locusts -- Control -- Argentina ( lcsh )


General Note:
Caption title.
General Note:
General Note:
"September 1947."
Statement of Responsibility:
by John R. Parker.

Record Information

Source Institution:
University of Florida
Rights Management:
This item is a work of the U.S. federal government and not subject to copyright pursuant to 17 U.S.C. §105.
Resource Identifier:
030294234 ( ALEPH )
780170345 ( OCLC )

Full Text

September 1947 -734

STATE VLLANT BOARD United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant quarantine


By John R. Parker
Division of Cereal and Forage Insect Investigations

It is indeed a great honor to be invited by your Government to
study the locust Droblem in Argentina and to offer suggestions for its
solution. It is an equally great privilege to become acquainted with the
friendly Deople of your country, to travel through its fertile agricultural
regions, and to report my studies to the authorities.

The Minister of Agriculture made it possible for me to visit the
Provinces most heavily infested with locusts and to consult at length
with personnel engaged in locust control and research. One could not
expect to become thoroughly familiar, by personal observation, with the
habits and reactions of locusts in Argentina in one brief visit. I
therefore devoted my time to studying the control measures now employed
and to learning all I could about the general problem from those most
familiar with it. This paper is a report of my impressions, and also
includes suggestions for future locust-control operations. The latter
are based on my observations in Argentina and on 30 years experience in
grasshopper control and research in the United States. They are offered
with some hesitation and with the feeling that perhaps I am doing too
much advising for one who has been in Argentina such a short time. How-
ever, since the official invitation from your Government asked for an
expert to "consult and advise with the Argentine Government on the
locust plague," I shall consider it a mandate to suggest and recommend
control measures which in my opinion are most likely to succeed.

The most outstanding impression resulting from my study of your
locust problem will be stated first, in order to make it the more emphatic.
It involves fundamental principles more than the actual methods of
killing locusts. Coming to your country in the midst of one of your
worst locust outbreaks, I was greatly surprised to find that no serious
attempt had been made to prevent it by destroying the insects while they
were concentrated in their winter quarters. I have noted the prompt and
successful emergency measures used to stamo out the few cases of bubonic

1/ Based on original, "La Lucha contra la Langosta en la Argentina,"
by this author, published by Argentina Minlsterio de A.grlcultura,
Direccion General de Sanidad Vegetal y Acridiologia, 20 pp. Buenos Aires,

SEP 2 2 1p7


plague that appeared recently in Buenos Aires. If such energetic action
had not been taken until the disease had become scattered throughout the
city, one can well imagine the great loss of life and the enormous cost
of finally eliminating the disease. It seems logical to believe that
similar basic principles should be employed in suppressing the locust
plague. This would mean being prepared and applying control measures
whenever locusts begin to increase abnormally, rather than searching for
weapons and starting to fight after large areas have been invaded.

From what I have read and from what your entomologists have told me,
the annual life cycle of the locust Schistocerca cancellata (Serv.)
expressed in brief outline, is essentially as follows: During nonoutbreak
years the entire life cycle is spent in parts of Argentina lying north of
the 30th parallel and in certain parts of Bolivia, Paraguay, and Brazil.
The boundaries of the permanent breeding areas have never been well
defined and undoubtedly change from year to year. When conditions for
locust reproduction become unusually favorable within the permanent
breeding grounds, swarms of adults migrate to points outside. Swarms
that invade Argentina leave their winter quarters within the permanent
breeding areas early in the spring and move progressively southward.
Eggs are deposited most abundantly in central Argentina between parallels
30 and 35. The eggs hatch within 25 to 35 days after deposition. The
length of the immature stages is approximately 6 weeks. The new adults
gather in swarms, which eventually return by various routes to the
permanent breeding grounds. By the beginning of cold weather in the
fall, the adult locusts have vacated the areas where eggs and immature
stages were most abundant and have begun to concentrate in preferred
localities within the permanent breeding grounds, where they spend the
winter months. Locust activities during the winter are dependent on
weather conditions, but are much more restricted than during the

With this brief outline of the life cycle in mind, let us compare
the possibilities for control within the permanent breeding grounds with
those in the outside areas which are invaded by migrating swarms. In
making this comparison, the following salient facts should be considered:

(1) All outbreaks originate in permanent breeding grounds north of
the 30th parallel.

(2) All adult locusts that survive the winter spend approximately
4 months within the permanent breeding grounds.

(3) During the fall and winter the adults concentrate in favored
localities where they are far less active than during the spring and
summer. This greatly reduces the area needing treatment and makes them
vulnerable to control with insecticides.

(4) For every female killed in the permanent breeding grounds, there
is the assurance that she will neither injure cro-os nor produce the several
hundred progeny which she might have done if allowed to migrate.


U. S. Bureau of Entomology and Plant Quarantine E-734,
Comments and Suggestions on Locust Control in Argentina

Page 7, paragraph 5, lines 8 to 14 should read:

With labor at 25 cents per hour and fuel at 41 cents per liter,
the cost is $4.25 per hectare, with no allowance for the original
cost of the flame thrower or for keeping it in cood operating condi-
tion. One hectare can be baited by one man in two-thirds of an hour
by hand spreading, and the cost of the bait per hectare is approxi-
mately 40 cents.

Page 13, paragraph 5, lines 2 to 4 should read:

In 1913, when large quantities of bait were first used, the
cost per ton was approximately $60; the present cost is only $15.


(5) Swarms of migratory locusts seldom stay lone in one place after
leaving the permanent breeding grounds. They are here today and gone
tomorrow. This makes it extremely difficult to control them with insecti-

(6) Immature stages originating from eggs laid by southward
migrating adults occupy a far greater area than did their parents in
the permanent breeding grounds.

(7) Immature stages can be successfully controlled, but since they
reach the adult stage aTooroximately 6 weeks after hatching, there is only
a short time in which to attack them.

All these facts indicate that the place to start fighting locusts
is in the permanent breeding grounds. The period during which control
operations can be conducted is longer, the area infested is smaller, and
the decreased activity and greater concentration of the adults increase
the chances for successful control with insecticides.

I am fully aware that the idea of fighting the Argentine locust
plague at its source is not original with me; I am merely urging the
adoption of a principle which has been advocated by many others. As early
as 1880 Conil declared that the source of invasion lay in the Gran Chaco;
in 1897 Bruner, a fellow countryman of mine, explored the Provinces of
Catamarca, Tucuman, and Entre Rios, where he found during the winter
immense numbers of locusts concentrated in the weeds and grasses and
recommended their destruction by fire. The first serious attempt to
study locusts in the permanent breeding grounds was during the period
1933-36. During this time the Argentine Government sent 14 scientific
commissions to explore the suspected source of outbreaks. Some of their
findings were as follows:

(1) That only excepDtionally do the foci extend beyond Argentine

(2) That it is possible to destroy the locust in its winter quarters.

(3) That while in cooler days the locusts remain stationar- on the
ground in layers 10 to 15 cm. thick and in clusters upon the trees, they
nevertheless embark on short midday flights on the warmer days.

The most recent recommendations to control locusts in the permanent
breeding areas are found in the resolutions passed at the Conferencia
International de IEpertoes en la Lucha Contra la Langosta, which was held
in Montevideo in September 1946.

Other names could be added to the list of those who have recommended
the destruction of locusts in the permanent breeding grounds, but enough
has been said to demonstrate that it is by no means a new idea. The
surprising thing is that with so much said, so little has been done.

Let us examine some of the probable reasons for the failure to act.


(1) Difficulty of exploring and conducting control operations
because much of the region in which the permanent breeding grounds are
located is inaccessible-by ordinary methods of travel. This is admittedly
a most difficult obstacle, but the chances of overcoming it are much
better than formerly. Jeeps, command cars, weapon carriers, bulldozers,
and other automotive equipment developed during the war can penetrate
terrain imp-assable to the ordinary motor car or truck. With landing
strips and supply depots established at strategic points, it is likely
that low-flying airplanes could be used for locating locust concentrations
possibly for the application of insecticides.

(2) Lack of continuous surveys and research to determine the limits
of the permanent breeding grounds and to give annual information on the
numbers of locusts within them. Without such information, outbreaks occur
without warning; no one is prepared, and all that can be done is to fight
a defensive battle in the zone of invasion. This could be remedied by
the employment of trained entomologists to work every year within the
permanent breeding grounds. Their principal task would be to locate
dangerous concentrations of the current year, estimate the size of the
areas needing treatment, and indicate when and where control measures
should be applied. These entomologists should also study the habits and
reactions of locusts within the permanent breeding grounds, to determine
the factors that permit abnormal increase, and thus be able to predict
incipient outbreaks.

(3) Lack of cooperative effort among the nations affected. The
limits of the permanent breeding grounds have never been clearly defined.
This has led to confusion in regard to the origin of migrating swarms and
lack of understanding as to each nation's responsibility. The resolutions
passed at the Montevideo Conference last June indicate that there is now
a desire to cooperate in mutual defense against the locust plague.

(4) Lack of sustained interest. When locusts are destroying crops,
defoliating fruit trees, and stopping trains, the demand for action
becomes so great that Government agencies are forced by popular demand to
do something about it. Any action taken at that late date, regardless of
the funds appropriated or an honest desire to spend them to the best
advantage, is crippled by lack of preparatory planning, shortages of
essential materials, and lack of trained personnel. When an outbreak is
over, nearly everyone wants to forget about it. This attitude is not
confined to Argentina; we face it continuously in the United States and
consider it the most important single obstacle to success in grasshopper
control. Unless some means can be found to support and sustain interest
in a long-range plan of locust control, after the current outbreak is
over, there will always be future outbreaks attended by the same con-
fusion and unpreparedness as before. If your powerful organization and
the commercial interests affected by locust depredations will urge and
support a permanent plani of locust control as a form of insurance, it
should be possible to suppress future incipient outbreaks within the
permanent breeding grounds and to prevent large-scale migrations to out-
side agricultural districts.


Having examined some of the reasons for failure to act in the past,
let us consider the possibilities for action now. To me they appear
brighter than ever before. New tyroes of vehicles and the airplane make
the permanent breeding grounds more accessible for surveys, research,
and control. New insecticides and new machines for mixing ana. applying
them have increased the effectiveness of control measures and reduced
their costs. The various nations affected by the swarms of locusts that
migrate from the permanent breeding grounds have expressed a willingness
to cooperate and apparently are merely waiting for someone to take the
initial action. The worst outbreak in years has aroused public interest
to the point where Government agencies should feel justified in taking
any action that gave promise of suppressing the locust plague.

Another source of encouragement for action now is the experience of
other nations. Controlling locusts before they invade cropped land is
not merely the dream or untried theory of entomologists, but instead is
a recognized successful practice.

The world's greatest authority on locust control, B. P. Uvarov,
head of the Anti-Locust Research Centre in London, has advocated it for
many years. Through his leadership, international agreements were entered
into for the exploration of the breeding grounds of Schistocerca
gregaria (Forsk.), which for centuries has periodically devastated large
areas in the nations surrounding the Mediterranean Sea. As in Argentina,
the breeding grounds of S. grearia are frequently remote from civilization
and inaccessible by roads. Locust-research offices made surveys under the
most trying conditions. They not only located many of the most important
breeding grounds but continued to inspect them annually and to give out
reports as to where dangerous infestations were to be expected. This
far-sighted policy proved to be of great value shortly after the beginning
of World War II, when locusts in the early-outbreak stage threatened to
destroy crons badly needed for food in several Mediterranean nations.
The promot dispatch of large, well-organized control units into desert
areas, where the locusts were destroyed with poisoned bait before they
became winged, prevented serious crop losses and drew much praise for the
locust-control organization. It is interesting to note that the first use
of a proprietary product containing benzene hexachloride as a poison in
locust bait was in this campaign.

A similar plan has been adopted for the control of the Mormon Cricket
(Anabras simolex Hald.) in the western part of the United States. Durii
nonoutbreak years this large wingless grasshooner is mostly confined to
a relatively few favorable localities in foothills and mountains remote
from agricultural lands. The beginning of an outbreak is marked by the
gathering of previously solitary individuals into bands, which start
migrating to lower country, where they increase enormously for several
years outside the limits of their permanent home. For many years little
was done to control them until the migrating bands reached crop~ei lar.inds.
By this time, many bands were so numerous and so large that control
measures costing hundreds of thousands of dollars were necessary to save
crops from destruction. Several years ago surveys were started to locate
the most important permanent breeding grounds. Many of them have been
mapped and are now inspected each year. Control measures will be amolled


at the first appearance of small bands within the permanent breeding
grounds. It is anticipated that this method will prevent future large
outbreaks and that the cost of prevention will be far less than the
large sums formerly spent for control after outbreaks had reached their

Now that I have taken so much of your time in urging the suppression
of the locust plague at its source, I regret that my brief experience in
Argentina leaves me unqualified to go on and propose a detailed plan to
accomplish it. This can be done best by your own leaders in locust
control and research, and I will therefore confine myself to the following
very general recommendations.

(1) The immediate dispatch of survey units directed by trained
entomologists to follow the movement of the swarms of adults, which are
now beginning their return flight to their winter quarters, and to locate
the zones in which concentrations of considerable magnitude occur.

(2) The immediate planning for mobile control units directed by
officers experienced in locust control and having for their objective
the destruction of locust concentrations discovered by the survey units.

(3) Continued activity by teams of survey and control units during
the winter months and as long thereafter as contact with large concentrations
can be maintained.

(4) Continuance of annual surveys of the permanent breeding areas
after the present outbreak is over and the application of control measures
in future years as soon as dangerous infestations are detected.

It is not to be expected that complete control of the present great
outbreak can be obtained in a single year. The odds are too great that
some of the swarms in the most inaccessible terrain will escape detection
and destruction and again fly south. This probability does not lessen
the need for an immediate attack on the locusts in their winter quarters.
Any large-scale reduction there is certain to result in fewer numbers,
less damage, and lowered cost of control in the invasion zone the
following summer. The insecticides to be used, the machines for applying
them, and the methods of transporting materials, equipment, and personnel
can only be determined by actual experience under the difficult conditions
existing in the permanent breeding grounds. This will hinder control
operations at the start, but if they are continued intensively during
1947 the experience and information gained should make it possible to
work much more effectively in 1948 and to bring the present outbreak to an
end that year.

This completes my arguments and recommendation to fight the locust
plague at its source. Many others before me have advocated similar
measures, but no sustained action has ever been attempted. Will there
continue to be inaction, or is there a person or some group of persons
with the vision and courage to act now? It is within your power, Sr.
Minister of Agriculture, to take this progressive step toward controlling


locusts in Argentina. If you authorize such a program and it is carried
out to a successful conclusion, your administration will long be
remembered for a great accomplishment.

Having stated the fundamental principles which, in my opinion,
should govern locust control in Argentina, I shall now discuss the
various techniques used in control operations.

The methods most commonly used in Argentina in the past have been
the destruction of eggs by disturbing the soil and the use of barriers
and flame throwers against the immature stages. All these measures have
some value, but in all other countries outside South America they have
been replaced by others less expensive, less time-consuming, and
usually more effective.

Egg destruction by working the soil is highly desirable if it can
be done as a part of regular farming operations, but if there is no
r iason to disturb the ground except to destroy eggs it will cost less
to let them hatch and destroy the young locusts by other methods.

It has been demonstrated many times over in Argentina that crops
can be Dprotected and enormous quantities of locusts can be destroyed by
the use of metal barriers. However, if the purchase price of the
barrier, and the labor involved in keeping it clean, moving it about,
setting it in place, patrolling it, and digging the pits are considered,
it will be found far more expensive than killing the locust with bait.
Barriers can sometimes be used to good advantage by enclosing brush- or
tree-covered rough land, or swamps where it would be difficult to apply
any other method of control. Locust bands within such areas are likely
to eventually move to the barriers where they can be destroyed. The
many kilometers of barriers now on hand should be reserved for such
situations and for emergency use in stopping invasions when materials
needed for less expensive control methods are not immediately available.

It has also been demonstrated in Argentina that immature locusts can
be controlled locally with flame throwers. Success depends on a large
supply of labor, fuel, effective machines, and close supervision; a
combination frequently difficult to obtain. Destruction of locusts by
flame throwers is dramatic and final, but like the use of barriers, it
is slow and expensive. Estimates based on my own observation and from
other sources indicate that 8 man-hours and 50 liters of fuel are needed
for each hectare (2.471 acres) treated with flame throwers. With labor
at per hour and fuel at Jacents per liter, the cost is $17 per
hectare, with no allowance for the original cost of the flame thrower or
for keening it in good operating condition. One hectare can be baited
by one man in two-thirds of an hour by hand spreading, and the cost of
the bait per hectare is approximately i-. From these figures it is
apparent that control with flame throwers is 12 times as slow and 7.5
times as expensive as control with poisoned bait. When it is st-ited
that two men scattering bait from a truck can bait h hectares per hour,
that mechanical broadcasters can bait 15 hectares per hour, and that
100 hectares per hour can be baited by means of an airplane, the vast


difference in time between control with flame throwers and with bait
becomes even more striking.

The use of poisoned bait has become the principal method of killing
grasshoppers and locusts in all parts of the world except South America.
In the .United States 1i0,000 tons have been used in a single season.
Some bait has been used in Argentina for the "Tucura,' but prior to 1946
it had never been used extensively against the locust. The main reasons
for not using it have been the slow kills obtained with baits containing
arsenic as the poison, and the fear of killing livestock when arsenical
baits were used carelessly. The use of benzene hexachloride, which kills
locusts much more quickly than arsenic and is harmless to livestock at
the strength used in baits, has overcome these objections. The fact that
locusts are affected shortly after tasting the bait and within an hour
are usually unable to jump or crawl makes a great impression on the
farmer who uses it. He praises it to his neighbors, and in most localities
this year the demand has been greater than could be supplied. If benzene
hexachloride had been available in larger quantities when locusts first
hatched, it would have greatly increased the effectiveness of this year's
control campaign. With the prospect of adequate supplies of benzene
hexachloride in future years, it seems certain that poisoned bait will
become the nrincipal weapon for fighting immature locusts in the agri-
cultural districts of Argentina. Whether it can be used successfully
against swarms of adults in the invasion zone or while they are in their
winter quarters can only be determined by experience: The possibilities
of using bait against adults should by all means be investigated.

The most important improvement in the use of poisoned bait during the
last 10 years in the United States has been the development of mechanical
equipment for its preparation and application. Standardized batch mixers
are now manufactured which require only 3 men to operate them at a
capacity of 2 tons of mixed bait per hour. Larger machines of the
continuous mixing type can turn out 15 tons per hour. In all but one of
the mixing stations I have seen in Argentina, all bait mixing is done by
hand; crews of 10 men mix approximately 1 ton per hour.

Power bait-broadcasting machines are now available which can discharge
bait over a swath 10-12 meters wide and bait 15 hectares per hour. One
man scattering bait by hand can spread approximately 1.5 hectares per hour.
Bait-broadcasting machines mounted on motor trucks and small rail cars
are used extensively in the United States for baiting highways and rail-
road rights-of-way.

In addition to reducing labor costs, the use of mixing and spreading
machines insures more uniform preparation and application than can be
obtained by hand methods. These machines also make it possible to pre-
pare and distribute either large or small quantities of bait quickly as
they are needed, without the wide variation in the number of workers
employed, as is the case when mixing and spreading are done by hand.

Photographs, drawings, and specifications of the standardized
bait-mixing and -spreading machines now used extensively in the United
States have been presented to those in charge of locust control in
Argentina. If it is desired to use these machines or similar ones in
next year's control campaign, their construction should be started
immediately. In my opinion the adoption of poisoned bait as the
standard control method and the extensive use of mechanical equipment
for mixing and spreading it are the two most important steps that
can be taken to obtain successful and economical control within the
invasion zone in central Argentina,

Although poisoned bait is usually the best method of killing
locusts, there are some conditions under which it fails to give
satisfactory results. It works best in low, open vegetation, where
the locusts can easily find it as they move about over the ground.
It is less effective in tall, densely growing vegetation which shades
the ground completely, and is least effective against locusts in trees
or thickly growing bushes. When conditions are unfavorable for baiting,
dusts and sprays, although much more expensive, are generally the best
method of control.

Chemicals that have given good results when used as dusts against
locusts and grasshoppers in Argentina and in other countries are
dinitro-ortho-cresol, benzene hexachloride, chlordane, and a chlorinated
camnhene. All these materials can also be used as sprays. Sprays have
the advantage of sticking longer to the foliage and are not as likely
to be blown away by wind. Disadvantages are the difficulties exoeri-
enced in some localities in obtaining and transporting water to preoare
the sprays and in obtaining satisfactory spraying machines.

Dinitro-ortho-cresol used in concentration needed for effective
locust control is likely to injure the foliage of cultivated crops. Its
use is therefore limited to areas in which injury to vegetation can be
disregarded. Large quantities of dinitro-ortho-cresol dust have already
been used successfully against locusts in Argentina.

Dinitro-ortho-cresol and benzene hexachloriae kill locusts very
quickly but they lose most of their toxicity within 24 hours after they
are applied. Chlordane and chlorinated camphene kill more slowly but
retain their toxicity for a longer period. In the United States single
applications of chlordane have continued to kill grasshoprers for
periods of 1 to 3 weeks. Killing the locusts present and protectingg
the treated vegetation from reinvasion by a single treatment is sometimes
a great advantage. It seems possible that barrier strips treated with
dusts or s-orays that retain their toxicity might prove useful in norctect-
ing crops and railroad rights-of-way that are subject to repeated locust
invasions. Such materials mip-ht also be used to protect vineyards,
orchards, and shade trees.

An important advantage in usin- dusts and sorays, and onp that partly
offsets their higher cost is the long ne-riod during which they can be
effectively anolied. Bait can be used only when the weather is fair and
the locusts are active, and best results are obtained when s-nreadin,- is


done early in the morning and late in the afternoon. Dusts and sprays
can be annlied from dawn until dark, or even at night, in any kind of
weather except during rain or high wind. The longer period for
effective work makes it possible to use labor more advantageously and
to proceed with control operations during periods when baiting should
not be attempted. Another advantage of dusts and sprays is that they
can be driven into thickets and the tops of trees where the locusts
could not be reached by other methods. Dusts or sprays seem the logical
materials to use against locusts in their winter quarters, but the
possibility of using bait in grasslands and open parks during the warmer
days should be investigated.

One of the main hindrances to successful control by dusting is the
difficulty in securing good dusting machines. Hand dusters are
notorious for their noor construction and faulty operations. Most of
them fail to discharge the dust evenly. This makes it extremely
difficult to obtain complete coverage and to apply the dust at the
desired rates per hectare. The usual thing is to use far more than

Large power dusters that can be calibrated to discharge dust at
the desired rate are essential to success in controlling large swarms
of locusts in trees, bushes, or other dense vegetation. A new type of
power snrayer-duster, which delivers an air stream of high volume and
velocity, now coming into use in the United States, has been founa
satisfactory for this Durnose. Either sprays or dusts can be introduced
in desired quantities into the air stream and carried to the tops of
very high trees or distributed widely over fiela crops. Machines of
this type were used very successfully during 194b for dusting and
spraying to control grasshopers in tall, dense stands of seed alfalfa
in which it was possible to dust or spray 15 hectares per hour, and
should be very effective in fighting locusts in their winter quarters.
Dust could be directed with great force into the tallest trees or
drifted for long distances through bushes and tall grass.

A-onlicatio'n of insecticides by airplanes has become a widespread
practice in the United St?.tes, and there are many companies and
individuals that do such work on a contract basis. Large quantities of
poisoned bait have been distributed by airplanes and they have been used
to a limited extent in the anplication of dusts and sprays for grasshopper
control. One company has developed a hopper and venture which is satis-
factory for either dust or bait, but most commercial dusting planes fall
to discharge bait evenly unless an agitator is installed in the hopper
to prevent the bait from backing. Planes spreading bait fly 12-15 meters
above the ground and cover a swath 15 meters wide. They fly at a speed
of 125-150 kilometers oer hour and carry loads of 400 to 450 kilos. If
landing strips and bait supplies are reasonably close, they can bait 100
hectares per hour. Dusts and sprays can be applied by lanes at about
the same number of hectares per hour as bait.

The use of planes for grasshopper control in the United States is
not considered practical except where large acreages are uniformly
infested and where landing strips and supplies can be established close
to the areas needing treatment.


If landing strips and supply stations can be constructed at
strategic points within the winter quarters of the locusts in northern
Argentina, airplane application of insecticides -night be used where
heavy concentrations were continuous over large areas or where difficult
terrain made it impossible to use ground equipment. Airplanes, particularly
the helicopter, should prove useful in locating locust concentrations.
It might also be possible to map infestations and estimate their size by
taking photographs from the air.

In discussing the technique of controlling locusts in Argentina, I
have purposely refrained from mentioning such details as the exact
formulation of baits, dusts, and sprays, the quantity to be used per
hectare, and the exact way in which they should be applied. These matters
can only be deter iined by the experience of your own leaders in locust
control and research under the many widely different conditions that
prevail in various arts of Argentina.

Lack of ti-ne and lack of knowledge of your lancua-e have prevented
me from making a careful study of the laws and methods of organization
which govern locust control in Argentina. From what I have learned on
my visits to several of tne Provinces, the general plan used this year
is about as follows: All suonlies and equipment are purchased by the
ministryy of Agriculture and delivered to central depots in the Provinces,
where they are kept in the custody of gov-rnnment officers who are also
responsible for directing locust control within their Provinces. From
the control denots the materials are distributed as needed to substations
from which they are delivered to the farmer or landowner. The cost of
operating the control depots and substations is borne by the Federal
Government. The only;r expense to the farmer or landowner is the cost of
labor used in conducting control on the land under his directions. The
Provincial Governments suoply labor for use in conducting control
operations on hi .h'.,'ays and the railroads are required to do the same on
their rights-of-wa:y. Each Province has its own locust-control committee,
which has the duty of organizin. the Province so that the materials and
equipment supplied by the Federal Government will be used to the greatest

This is essentially the same tye of organization that is used for
grasshopper control in the United States. It has been our experience
that success depends on the closest cooperation between Federal and
Provincial agencies and the selection of men for the Provincial coraittees
who are recognized leaders in their own communities. Only men of tnis
type can inspire the united action needed for successful control.

Mly observations in Argentina indicate that the railroads have been
prompt and faithful in conducting locust control on their properties and
that most farmers .rowing cultivated crops have attempted to control
locusts on their own land. Locust control seems to have been most
neglected on large holin-s of uncultivated land where there is no
immediate urge to protect valuable crons. Some owners of such land have
been public spirited enou--h to coop-erate wholeheartedly in locust control,
but others have done as little as possible. Bands of immature locusts,
mnigratine frnm noncultivated lan:a, have attacked nearby crops ane have caused


many -train stoppages by massing on railroad rights-of-way previously
cleared of locusts by railway employees. Some way should be found to
eliminate this weak spot in control operations. Perhaps it could be
done by notifying the landowner'that unless his property was cleared
of locusts by a given date control would be accomplished by Federal or
Provincial crews at his expense. Some of our States have laws*that
permit this course of action and provide that the cost shall be charged
against the owner as taxes.

In organizing any insect-control program there is great need to
educate the persons who are expected to use the control methods. This
can be done by technical bulletins, newspaper articles, radio broadcasts,
and posters, but in my experience none of these have been so effective
as holding meetings at which control methods were actually demonstrated.
Proper mixing and spreading of poisoned bait can be learned more quickly
by seeing it done than by reading or hearing about it. I am not .familiar
with the methods used in Argentina to arouse interest in locust control
and to insure the proper use of equipment and materials, but I know from
experience that a well-organized educational program will result in
greater participation and more intelligent effort than an unorganized

Successful and economic insect-control depends largely on research.
In the life cycle of every insect there are periods when it is most
susceptible to attack. When the weak spots in its armor have been
discovered, the next thing is to select the best weapons for the attack.
These may be chemical, mechanical, or biological, or a combination of
all three. Even after an apparently satisfactory control program is in
operation, there is always the chance that new chemicals, new equipment,
and new information on the insect's behavior may make it possible to
obtain even better results at a lower cost. Determining the periods
when the insect is most vulnerable, selecting the best control measures
available, and continuing the search for better methods can be done best
by experienced and well-trained entomologists who are unhampered by the
confining duties of conducting control operations. Personnel engaged
primarily for control are selected for their ability as administrators
and field supervisors, and generally do not have the time, training, or
experience needed for productive research. Best results may be expected
when control and research organizations cooperate in a unified program.
Each unit has its own assignment, but each should help the other in
their mutual problem of attempting to control the same insect.

All these general principles apply directly to the solution of the
locust problem in Argentina.

Further studies of the life cycle and behavior of locusts,
particularly within the permanent breeding grounds, are needed to
determine when and where control measures can be applied most effectively.
Such studies should not overlook the possibility of utilizing parasites,
predators, and disease to supplement other control measures.

Intensive surveys and investigations should be continued within
the permanent breeding grounds after the present outbreak has ended.
Their main objective would be to determine tne factors that cause
outbreaks and to locate the places where locusts first start to increase
to dangerous numbers. The prompt application of control measures at
such, points might prevent the occurrence of an extensive outbreak.

Detailed studies of the migration routes and activities of locust
swarms in relation to weather conditions are desirable. Similar studies
of the desert locust (Schistocerca gregaria) have been conducted in
East Africa for the last 16 years and, as a result, it is now possible
to forecast impending invasions with accuracy.

There is a need in Argentina to determine the minimum effective
dosages of various chemicals that have already been used to kill locusts,
and of new insecticides that are constantly ap-opearing. The use of
insecticides at greater strengths than needed increases the cost of
control and, during periods of limited sunply, decreases the area that
can be treated. Investigations to determine the best time and means
for applying the insecticides are needed. All these things require
field tests, repeated many times, before definite conclusions can be

The probable extensive use of poisoned bait in future locust-control
cainaigns in Argentina will require constant rese-rch. Great quantities
of poisoned bait have been used in the United States for many years, but
research to make it more effective and less expensive still continues.

Bait investigations in the United States have already oaid enormous
dividends by decreasing the cost without loss of effectiveness. In 1913
when large quantities of bait were first used, the cost per ton was
approximately $v ; the present cost is only $W.'' The more expensive
bait would still be used if extensive research had not demonstrated that
the citrus fruits, molasses, and high percentage of bran formerly used
were unnecessary. The reduction in the cost of bait brought about by
research has paid many times over for all the grasshopor research
conducted in the United States.

Only the most urgent problems needing research attention in Argentina
have been mentioned, but enough has been said to indicate the magnitude
of the field in which research is needed.

Considerable expansion of your small but competent locust-research
unit will be required to obtain the information needed to enable your
control unit to function most efficiently. Investment of public funds
for this purpose should yield large dividends in reducing the cost of
control as well as making it more effective.

In my estimation, the way to make most rapid progress toa-prd the
solution of the locust problem in Argentina is to -rovide increased
facilities for research and to have your control and research organizations
work together on a comprehensive program to control the locust plague at
its source.


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In closing, I wish to express my thanks to the many persons who have
given me frier.dl/ assistance while I have been in Argentir.a. It would
take too much space to naiie them all, but I wish particularly to express
Mny gratitude to the following persons: Sr. Juan Carlos Picazo Elordy,
the I-tihister of Agriculture, who extended a most cordial welcome on Miy
arrival in Areentina and authorized me to use the facilities of the
Lucha contra las Plagas in making my studies. Arturo .odrigauez Jurado,
director of the Lucha contra las PlI:as, whose friendly assistance
enabled me to see all phases of locust control and to visit several of
the most heavily infested Provinces; Sr. Julio Gaston, Insoector GenerAl,
la Lucha contra las Ple--s, who accompanied me on several trips and
assisted in arranging for others; Dr. Alejandro Ogloblln, jefe del
Laborptorio Central de Acridiologia, who generously took time from his
own work to accompany me on nearly all my trios and to assist in conduct-
ing tests of new insecticides. Because of his long experience in studying
locusts in Argentina, he was able to explain their habits and behavior
as we encountered them on our trip. Sr. John H. Tayloro principal
assistant to the chief engineer of the Central Argentine Railway, kindly
took me on several trios which provided information on the part played
by the railways in controlling locusts, and also assisted in testing
new insecticides. without t the help of these men this paper could not
have been written.

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