September 1947 E-734- LIBRARY STATE PLANT BOARD United States Department of Agriculture Agricultural Research Administration Bureau of Entomology and Plant quarantine COMMENTS AND SUGGESTIONS ON LOCUST CONTROL IN ARGENTINA!/ By John R. Parker Division of Cereal and Forage Insect Investigations It is indeed a great honor to he invited by your Government to study the loctist T>roblem in Argentina and to offer suggestions for its solution. It is an equally great privilege to become acquainted with the friendly neople 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 stanro out the few cases of bubonic l/ Based on original, "La Lucha contra la Langosta en la Argentina," by this author, Dublished by Argentina Ministerio de Agricultura, Direccion General de Sanidad Vegetal y Acridiologia, 20 -do. Buenos Aires, 19^7. SEP 2 2 ■ -2- 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. Thi6 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, 6warms 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 *° 35 clays 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 summer. 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 h 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. (U) For every female killed in the permanent breeding grounds, there is the assurance that she will neither injure crops nor produce the several hundred progeny which she might have done if allowed to migrate. CORRECTION SLIP U. S. Bureau of Entomology and Plant Quarantine E-73^, Comments and Suggestions on Locust Control in Argentina Page 7, paragraph 5, lines 8 to 1^ should read: With labor at 25 cents per hour and fuel at k-2 cents per liter, the cost is $U.25 per hectare, with no allowance for the original cost of the flame thrower or for heeping it in good 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 hO cents. Page 13, paragraph 5, lines 2 to h 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. Digitized by the Internet Archive in 2013 http://archive.org/details/cogestiOOunit -3- (5) Swarms of migratory locusts seldom stay long 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- cides. (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 approximately 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 av/are 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 1S80 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, Tucuraan, and "Entre Rios, where he found during the winter immense number? 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 1933~3k» 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 exceptionally do the foci extend beyond Argentine territory. (2) That it is possible to destroy the locust in its winter quarters, (3) That while in cooler days the locusts remain stationary 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 Internacional de TSxpertoes en la Lucha Contra la Langosta, which was held in Montevideo in September 194b. 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. -u- (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 impassable 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 oy_f_r, 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 plan' of locust control as a form of insurance, it should be possible to suppress future incipient outbreaks within the r>ermanent breeding grounds and to prevent large-scale migrations to out- side agricultural districts. -5- Having examined some of the reasons for failure to act in the past, let us consider the possibilities for action now. To me they apcear brighter than ever before. New types 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' 8 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 Schis tqcerca 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. gregaria 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 crops badly needed for food in several Mediterranean nations. The proarot 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 ( Anab ras simp lex Hald.) in the western part of the United States. During nonoutbreak years this large wingless grasshopper 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 cropped lands. 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 a^olied -6- 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 peak. 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. (U) 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 19^8 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 -7- 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 reason 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 protected 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-cov?red 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.UJ1 acres) treated with flame throwers. With labor at ^ per hour and fuel at 3jft r cents 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 &!t&0. 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 stated that two men scattering bait from a truck can bait U 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 -8- 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 lUO.OOO tons have been used in a single season. Some bait has been used in Argentina for the "Tucura^ 1 but prior to I9U6 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 -principal weaoon 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 experienced 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. -q- Photographs, drawings, and specifications of the standardized bait-mixing and -spreading machines nov 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 canrohene. 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 experi- enced in some localities in obtaining and transporting water to prepare 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 hexachloride 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 grasshoppers for periods of 1 to 3 weeks. Killing the locusts present and protecting 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 -orctect- ing crops and railroad rights-of-way that are subject to repeated locust invasions. Such materials might also be used to protect vineyards, orchards, and shade trees. An important advantage in usin, J have caused -12- 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 program. 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. -13- Intensive surveys and investigations should be continued within the oerrnanent breeding grounds after the present outbreak has ended. Their main objective woulc be to determine tne factors tnat cause outbreaks and to locate the places where locusts first start to increase to dangerous numbers. The prompt application of control measures at 4 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 ( Schistocerc a gregaria ) have been conducted in East Africa for the last lb 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 appearing. The use of insecticides at greater strengths than needed increases the cost of control and, during periods of limited supply, 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 drawn. The -orobable extensive use of poisoned bait in future locust-control campaigns in Argentina will require constant rese~rch. f >reat 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 paid 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' $&ffiSt; the present cost is only $^.°' 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 grasshopper 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 i6 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 toverd the solution of the locust problem in Argentina is to provide 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. UNIVERSITY OF FLORIDA -lk- 3 1262 09239 2405 In closing, I wish to express my thanks to the many persons who have given me friendly assistance while I have been in Argentina. It would take too much space to name them all, but I wish particularly to express my gratitude to the following persons: Sr. Juan Carlos Picazo Elordy, the Minister of Agriculture, who extended a most cordial welcome on my arrival in Argentina and authorized me to use the facilities of the Lucha contra las Plagas in making my studies. Arturo Rodriguez Jurado, director of the Lucha contra las Plagas , 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, Inspector General, la Lucha contra las Plagas, who accomoanied me on several trips and assisted in arranging for others; Dr. Alejandro Ogloblin, jefe del L aboratorio Central de Acridi o logia , who generously took time from his own work to acconnany 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. Taylor* principal assistant to the chief engineer of the Central Argentine Railway, kindly took me on severa.1 trit»s which nrovided information on the part played by the railways in controlling locusts, and also assisted in testing new insecticides. Without the help of these men this naper could not have been written.