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Studies on the biology of ants associated with citrus trees

  • Authors: Myers, N J
  • Date: 1957
  • Subjects: Citrus -- Diseases and pests -- Biological control -- South Africa , Ants -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5869 , http://hdl.handle.net/10962/d1012923
  • Description: Several ant species may be associated with the same honeydew producing insect in citrus orchards. Recently antagonism and competition between two such ants were reported from Letaba. This report stimulated the present study, the purpose of which is to ascertain which ant species are most numerous in citrus orchards ln the Eastern Cape Province; the reasons for these ants being able to occupy orchards; and, finally, their relationships. A survey of the Sundays River Valley and the Fish River Valley revealed that three species - Anoplolepis custodiens Smith, Anoplolepis steingroeveri Forel, and Pheidole megacephala Fabricius - were commonly found in citrus orchards in association with Soft Brown Scale insects. The territorial relationships of these ants were determined by plotting their distribution at intervals for over a year. It was found that this distribution could be correlated with seasonal climatic conditions, the effects of farming practices, brood rearing requirements and behavioural differences between the three species. The ant, A.steingroeveri, had not been previously studied, and since foraging is an integral part of territorial behaviour, some aspects of its biology, and more especially its foraging activity, were investigated to compare it with the known biology of the other two species. Observations on the foraging activity of A. steingroeveri were made at monthly lntervals for almost a year, and correlated with climatic conditions prevailing at the time. Some seasonal and dally variations in foraging behaviour could not be readily explained in terms of the effects of temperature and humidity on the ants. Other factors, includ1ng trophallactic stimulation and overcast skies, were found to influence ant activity. Owing to the apparent lack of information in the literature and possibility of periodic honeydew production by Soft Brown Scale insects controlling ant activity was investigated in the laboratory. The results of this study showed that it was not likely that honeydew excretion restricted the activity of the ants. Several investigators have also found that many interrelated climatic factors correlated with ant foraging behaviour, but have expressed dissatisfaction at not being able to reach the crux of the matter. To clarify the issue a constant temperature chamber was constructed in which a colony of Crematogaster ants was housed and the ants were subjected to a series of temperatures at different humidities, all other factors were eliminated or kept constant. The effects of these two factors on the thermokinetics and foraging activity of the ants were registered. This thesis contains several sections and at the end of each the results are discussed in the light of the available literature and comparisons are drawn between the species under investigation. The main results are given in the summary. After the summary two appendices are included. One is an attempt to compare the effect on ant size of the honeydew diet of orchard colonies with the proteinaceoue diet of veld ants. The other appendix is an experiment to control citrus ants with an insecticide.
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  • Date Issued: 1957

The morphology of the Weberian apparatus of Labeo umbratus Smith

  • Authors: Dennis, Clive Roy
  • Date: 1957
  • Subjects: Fishes -- Anatomy -- South Africa , Weberian apparatus -- Morphology , Fishes -- South Africa -- Tyumie River , Eastern Cape (South Africa) -- Fishes
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5907 , http://hdl.handle.net/10962/d1014766
  • Description: In Labeo umbratus only the first three anterior vertebrae undergo any modification. These vertebrae are not completely anchylosed with each other and are closely associated with the four Weberian ossicles. Movement is however restricted between these vertebrae since this is essential for the efficient functioning of the Weberian ossicles. The first vertebra is well developed the absence of a spinous process and neural arch in the first vertebra may perhaps be explained by the findings of some workers who derive the claustrum from the former and the scaphium from the latter. A small muscle has its origin on the claustrum and its insertion in the angle formed by the dorsal and medial processes of the scaphium. A second muscle originates in the pit-like excavation of the first vertebra and is inserted on the ventral process of the scaphium. The intercalarium possesses horizontal, articular and ascending processes; a portion of the horizontal process being imbedded in the interossicular ligament. In Labeo umbratus it is unlikely that the intercalarium represents (if it does so at all) the entire neural arch of the second vertebra. From a morphological point of view it seems likely that the intercalarium may function as a lever. A transversely situated ductus endolymphaticus joins the two sacculi to each other. The sagitta, in the region of the ductus endolymphaticus has a long, lateral "wing-like" process which projects into the cavity of the sacculus. The sacculus anilagena are innervated by the n. saccularis and the n. lagenaris respectively. The ductus endolymphaticus is prolonged posteriorly into a median unpaired sinus endolymphaticus. Although the only serious objection to Weber's theory is the fact that there could be no differential action of the two ears, the basic idea seems valid. Sagemehl's theory cannot be accepted. It seems likely that the Weberian ossicles are necessary structures for audition and to the hydrostatia function of the air-bladder.
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  • Date Issued: 1957

The solubility of barium sulphate in water at 25°

  • Authors: Rosseinsky, D R
  • Date: 1957
  • Subjects: Chemistry, Physical and theoretical , Solubility , Barium sulfate
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4491 , http://hdl.handle.net/10962/d1013097
  • Description: Barium sulphate is a widely used analytical precipitate and for this reason its properties have been extensively studied. The variety of results encountered with barium sulphate samples prepared by different methods is an indication of the complex nature of this interesting substance. Intro., p. 8.
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  • Date Issued: 1957

Verkenninge in die woordeskat van die poësie met spesiale verwysing na N. P. van Wyk Louw

  • Authors: De Villiers, Aart
  • Date: 1957
  • Subjects: Louw, N. P. van Wyk (Nicolaas Petrus van Wyk), 1906-1970 -- Criticism and interpretation , Afrikaans poetry -- History and criticism
  • Language: Afrikaans
  • Type: Thesis , Masters , MA
  • Identifier: vital:3644 , http://hdl.handle.net/10962/d1014742
  • Description: [From Introduction]. Soos die titel aandui, wil hierdie skripsie bloot verkenninge wees. Dit sal vir die leser duidelik wees dat dieselfde metode van benadering wat ek hier op sekere aspekte van die woordeskat van van Wyk Louw se poësie toegepas het, ook op ander woordsoorte toegepas sou kan word, en ook op die werk van ander digters. As 'n mens die gegewens wat jy so verkry, histories sou beskou, sou jy 'n baie interessante kykie kry op die ontwikkeling van die woordeskat in die Afrikaanse poësie. ln die beste van een skripsie is so iets egter, soos duidelik sal blyk, nie moontlik nie. Later, voel ek, sou miskien met vrug op dié grondslag voortgebou kan word.
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  • Date Issued: 1957

A preliminary study of adaptation and inhibition of reflex claw opening in the crab Potamon perlatus (Milne Edwards)

  • Authors: Bush, Brian M H
  • Date: 1956
  • Subjects: Crabs , Decapoda
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5906 , http://hdl.handle.net/10962/d1014683
  • Description: The only recorded experimental attempt to determine the functional, biological significance of peripheral inhibition in the Crustacea is that of Hoffmann (1914). From a series of experiments on Astacus fluviatilis L. involving transsection of the opener inhibitor and motor axons of the cheliped, he concluded that the opener inhibitor axon of the claw responded to prolonged or repeated sensory stimulation by transmitting inhibitory impulses to the opener muscle, the peripheral inhibition thus evoked causing adaptation of the reflex opening responses of the claw to the sensory stimulation. This suggests that there may be (1) a very high degree of peripheral control of (a) the reactions of the animal to external stimuli, and perhaps also to proprioceptive stimuli, and therefore (b) of the behaviour of the animal; and (2) a correspondingly high degree of independence of this behaviour from central nervous control. It is therefore of importance to discover whether, in fact, this conclusion is valid for Astacus and other Decapod Crustacea, and if so, then to what extent the adaptation is peripherally controlled. A preliminary attempt haa been made to repeat these experiments of Hoffmann, using Potamon perlatus (M.Edw.). Experiments in which mechanical sensory stimulation was used to evoke reflex claw opening indicated that this conclusion is not applicable to P.perlatus. The adaptation of the mechanical claw openining responses which occurred with repeated sensory stimulation was not affected by transsection of either the specific opener inhibitor axon or the common inhibitor axon of the claw. It was evidently mainly due to sensory adaptation when the sensory stimuli were heavy, and to centrally controlled adaptation when the sensory stimuli were light. The significance of these results is discussed. Other effects observed during the course of the work, of electrical "sensory" stimulation, and of cerebral ganglion elimination, are also described and discussed in relation to the present problem.
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  • Date Issued: 1956

Robert Godlonton as architect of frontier opinion, with special reference to the politics of separatism, 1850-57

Scientific management as applied to a South African sweet factory

  • Authors: Bernstein, Jack
  • Date: 1956
  • Subjects: Candy industry -- Management , Candy industry -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:1111 , http://hdl.handle.net/10962/d1013494
  • Description: From Chapter 1: Among the many problems that the sweet industry in this country has had to overcome was the prejudice which favoured imported confectionery as against the local product. Fortunately this prejudice is slowly disappearing, firstly because imported sweets are largely unobtainable, and, secondly because the quality of the South African manufactured article has improved tremendously. Both the quantity and value of sweets produced in this country have increased over the last decade...
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  • Date Issued: 1956

Some aspects of the micro-arthropod fauna in the soils of pineapple fields in the Bathurst division, Eastern Cape Province

  • Authors: Graham, P
  • Date: 1956
  • Subjects: Pineapple , Soils -- South Africa -- Eastern Cape , Soil surveys -- South Africa -- Eastern Cape , Soil science , Arthropoda -- South Africa , Arthropod pests -- South Africa , Soil animals
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5853 , http://hdl.handle.net/10962/d1012087 , Pineapple , Soils -- South Africa -- Eastern Cape , Soil surveys -- South Africa -- Eastern Cape , Soil science , Arthropoda -- South Africa , Arthropod pests -- South Africa , Soil animals
  • Description: Although a considerable amount of work has been done on the fauna of the soil of temperate forests and pastures, very little is known about that of tropical and sub-tropical soils. Most of the work on tropical soils concerns the fauna of tropical forests ... . The present investigation represents an attempt to discover the effect of an imported perennial tropical and sub-tropical plant, the Pineapple, on the soil fauna of a semi-arid region (rainfall 15-25 inches). Intro., p. 1-2
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  • Date Issued: 1956

The fungal flora associated with black spot of pineapples

  • Authors: Edmonstone-Sammons, Chloris
  • Date: 1956
  • Subjects: Fungi , Pineapple -- Diseases and pests , Citrus -- Diseases and pests , Citrus -- Soils
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4258 , http://hdl.handle.net/10962/d1011738 , Fungi , Pineapple -- Diseases and pests , Citrus -- Diseases and pests , Citrus -- Soils
  • Description: The earliest reference to investigations of "black spot" in pineapples is made by Tryon (1898), who refers to the work of Dr A. A. Brown (1896) of the stock Branch, Victoria (Aus.), who sectioned diseased areas of pineapples and found fungal spores and hyphae in the tissues. The symptoms of this socalled "fruitlet core rot," are described by Tryon as: "well defined dark brown markings immediately beneath the surface, and passing inwards to a depth of 1/4" to 1/2"- the malady commencing in separate fruitlets, the central core of the fruit remaining quite healthy." (This description agrees with the symptoms referred to as "black spot" 1n this country). Subsequent culture of the spores (found by Brown) on slices of healthy fruit resulted in growth of Mucor racemosus. Brown regarded an invasion by this fungus as a primary cause of the disease. Intro. p. 1.
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  • Date Issued: 1956

A critical study of methods for the determination of zinc in soils and plant materials

  • Authors: Eve, Desmond John
  • Date: 1955
  • Subjects: Soils -- Zinc content , Soils -- Analysis , Plants -- Analysis
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4468 , http://hdl.handle.net/10962/d1011770 , Soils -- Zinc content , Soils -- Analysis , Plants -- Analysis
  • Description: Although it is only fairly recently that the importance of trace elements in plant nutrition has been established, enormous advances have been made in this field of research and numerous publications of considerable scientific and economic importance, dealing with the subject, have appeared. The physiological functions of zinc in promoting plant growth have not all been satisfactorily identified as yet. There are indications, however, that zinc acts as a catalyst or regulator in plant metabolism. It appears too, that the element plays some role in chlorophyll formation. Zinc deficiency is associated with leaf chlorosis and a general collapse of v ital processes. The analysis of leaves and soils has become an essential part of the study of the nutritional diseases of plants and it is imperative that accurate and reliable methods of analysis should be available. Intro. p. 1.
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  • Date Issued: 1955

A sample survey of farming types in the divisions of Albany and Bathurst

  • Authors: Davies, R J
  • Date: 1955
  • Subjects: Agriculture -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4885 , http://hdl.handle.net/10962/d1014733
  • Description: [From Introduction]. It is the purpose of this thesis to examine some of the broad relationships which exist between different land use types and farming practises on the one hand and the geographical environment on the other. The enquiry is confined to the study of a number of farm units which have been selected within the area enclosed by the District of Albany and Bathurst situated in the south-East coastal belt of the Cape Province. The procedure adapted conforms broadly to that of a project carried out in South America by R.S. Platt of the University of Chicago and embodied in hls book "Latin America, Countryside and United Regions." Platt's project, he notes, consists of a collection of "small field studies in a frame of complex generalisations." It does not aim to give a complete geographical account of the regions he selected for investigation, but is an attempt to enlarge geograpical understanding of the respective areas.
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  • Date Issued: 1955

An investigation into the insect ecology of citrus orchards, with special reference to citrus mussel scale (Lepidosaphes beckii newm.)

  • Authors: Carnegie, Alistair John Michael
  • Date: 1955
  • Subjects: Citrus -- Diseases and pests -- South Africa -- Eastern Cape , Lepidosaphes
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5905 , http://hdl.handle.net/10962/d1014637
  • Description: In the course cf the last fifteen years the general lnsect ecology of citrus orchards in the Eastern Cape has provided the subject matter of four theses presented for the degree of M.Sc. of Rhodes University. The false codlin moth, Argyroploce leucotreta Meyr., formed the subject of a thesis by Horne in 1939. Then in 1941 the same insect formed the subject matter of a thesis by Harris. The general ecology of a citrus orchard, with special regard to the biological control of citrus red scale, Aonidiella aurantii Mask., was the subject matter of Whitehead's thesis in 1948. This was a much more general investigation than the preceding two theses, and touched on many more aspects of citrus ecology. Another thesis dealing with more general citrus ecology was that of Smithers in 1953.
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  • Date Issued: 1955

Studies of Hypnea spicifera

  • Authors: Hewitt, Florence E
  • Date: 1955
  • Subjects: Marine algae
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4271 , http://hdl.handle.net/10962/d1018234
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  • Date Issued: 1955

A preliminary investigation of the toxic principle of Moraea polystachya Ker

  • Authors: Dry, L J
  • Date: 1954
  • Subjects: Iridaceae Moraea polystachya ker
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4461 , http://hdl.handle.net/10962/d1011494
  • Description: A member of the Iridaceae family, the plant (also known as the Blue Tulp) ... is a monocotyledon. The blue tulp grows profusely in rainy parts of the Union, for example along much of the Cape coastal belt as far east as Grahamstown, in both the Karroos, and in parts of the Transvaal. It is a perennial plant but only appears above the ground once a year for about two months. This is at the start of the rainy season and in Grahamstown the plant appears in April and May, after which it disappears again. Chapter 1, p.1.
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  • Date Issued: 1954

An investigation of the equivalent circuit of a conductivity cell

  • Authors: Allison, Francis Sutton
  • Date: 1954
  • Subjects: Electrolytic cells
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4508 , http://hdl.handle.net/10962/d1013376
  • Description: ( i) A linear circuit is shown not to explain the behaviour of a conductivity cell towards a long rectangular pulse of amplitude less than the decomposition potential of the solution in the cell. (ii) It is shown that the flow of current through the cell is governed by diffusion to the electrode. The diffusion current expression is the familiar one used in the case of diffusion up to a plane micro-electrode, except that in this case the concentration in the layer next to the electrode is not zero, but only somewhat less than the bulk concentration. (iii) Except during a short initial period (less than 10 seconds), the resistance of the electrolytic cell varies directly with the square root of the time for which an e.m.f. (less than the decomposition potential) is applied to the cell, and inversely with the concentration difference between the electrode surface and the bulk of the solution.
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  • Date Issued: 1954

Aspects of the resorcinol-formaldehyde condensation

  • Authors: Waldron, Ronald Augustus Frank
  • Date: 1954
  • Subjects: Resorcinol , Formaldehyde
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4514 , http://hdl.handle.net/10962/d1013460
  • Description: An attempt was made to producea -β or Ϫ - resorcinyl alcohol from disubstituted resorcinyls. To accomplish this 3,5-dibromo-β-resorcylic acid was reacted with lithium aluminium hybride, a mild reducing agent, in an attempt to reduce the acid group to the alcohol group. This disubstituted resorcinol was recovered unchanged. 3,5-dibromo-β-resorcyl-aldehyde was reduced by lithium aluminium hydride, but, instead of the alcohol forming, resinification took place. 2-methyl- 4-ethylresorcinol and 4,6-diethyrecorinol were reacted with formaldehyde under alkaline and acidic conditions. In each case a resin formed. The above experlments indicated that condensation took place in the meta position of the resorcinol molecule. Trimethylresorcinol was therefore reacted with formaldehyde under alkaline conditions, resulting in a small quantity ot the alcohol derivative. A better yield of the alcohol derivative was obtained by the hydrolysis or the chloromathyl derivative. In pursuing this line, a seres of new compounds and their derivatives were prepared. The condensation of the alcohol derivative with trimethylresorcinol and also with resorcinol was investigated.
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  • Date Issued: 1954

Defoe and Scottish politics after union

  • Authors: Gathorne, R
  • Date: 1954
  • Subjects: Defoe, Daniel, 1661?-1731 -- Political and social views , Scotland -- History -- 1689-1745
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2605 , http://hdl.handle.net/10962/d1011941
  • Description: It would indeed have been a difficult matter for anybody possessing a taste for self-expression, a facility with words and an insatiable imagination to avoid becoming involved in political controversy in England during the early part of the Eighteenth Century. For one who, in addition, was confident in his ability to solve problems of state of whatever complexity it was clearly an impossibility. Daniel Defoe's close connection with politics during the first years of the Eighteenth Century involved him in numerous hardships. In later years it brought him much less fame than his excursions into fiction; but it was the means of providing him, albeit sparsely at times, with sufficient money to keep his creditors at bay. On more than one occasion the protection he gained helped to rescue him from imprisonment. Intro., p. 1.
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  • Date Issued: 1954

Die aktualiteit in die poësie van A Roland Holst

  • Authors: Bezuidenhout, Gertruida Catharina
  • Date: 1954
  • Subjects: Roland Holst, Adrianus, 1888-1976 -- Criticism and interpretation , Dutch poetry -- 20th century -- History and criticism
  • Language: Afrikaans
  • Type: Thesis , Masters , MA
  • Identifier: vital:3639 , http://hdl.handle.net/10962/d1013499
  • Description: From Verantwoording: By die ondersoek na die rol wat die aktualiteit in die poësie van A. Roland Holst speel, wou ons veral nagaan of die gedigte waarin elemente van die aktualiteit aanwesig is, in wese van sy orige werk verskil. Hoofstuk II, “Teen die Wereld” gaan veral sover dit die inhoud betref, op hierdie vraag in. In die derde en vierde hoofstukke is na aanleiding van ‘n aantal verteenwoordigende gedigte getrag om meer in besonderhede, en ook wat die vorm aangaan, die saak van nader te beskou, en die resultate van die ondersoek is in die Slotbeskouing saamgevat.
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  • Date Issued: 1954

Some aspects of the insect ecology of citrus orchards

  • Authors: Smithers, Courtenay Neville
  • Date: 1954
  • Subjects: Citrus -- Diseases and pests , Insect pests
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5883 , http://hdl.handle.net/10962/d1013231
  • Description: After a brief introduction, the species of Citrus on which the investigations were carried out are mentioned. This is followed by an account of the methods of collection used, and a discussion of their relative merits. The main method used was that in which the trees were fumigated with hydrocyanic acid gas, and the insects falling from the trees were taken up on sheets. The location of the areas where collections were made are then given. An annotated list of the species taken by the fumigation method follows, and the numerical data obtained at the same time regarding the species present is given in an abbreviated form and discussed. A more detailed discussion of the relative abundance of the species is then undertaken. The discussion of the ecology of the insects commences with the insects listed according to their activities, so far as known, and an account of five trees of striking faunal differences is given. A broader discussion of citrus ecology is then given, based on the data previously presented; this ends with a short reminder of the inherent 'oneness' of the insect with its environment.
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  • Date Issued: 1954

Studies on the behaviour of Anomala opacicollis (Pér)

  • Authors: Miles, Peter Wallace
  • Date: 1954
  • Subjects: Anomala -- Behavior -- Zimbabwe , Anomala -- Control -- Zimbabwe , Anomala -- Larvae -- Zimbabwe , Scarabaeidae -- Zimbabwe , Beetles -- Control -- Zimbabwe , Tobacco -- Diseases and pests -- Zimbabwe , Tobacco industry -- Zimbabwe , Insecticides -- Zimbabwe
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5901 , http://hdl.handle.net/10962/d1013514
  • Description: [Summary]: The larvae of Anomala opacicollis (Pér), of Melolonthid and of other Rutelid species, attack tobacco in Southern Rhodesia, and are more commonly called "whitegrubs". Whitegrubs are widespread in the sandveld areas where tobacco is grown and, at the Trelawney Station of the Tobacco Research Board of Southern Rhodesia, where this work was done, A. opacicollis was the predominant species. An account o£ the one year life cycle is given. The adults eat the leaves of various indigenous trees and an account of an experiment on the food preferences of A. opacicollis adults is given, and the main food sources in the Trelawney area are listed. An experiment is described which shows that the beetles prefer to lay their eggs in the veld or in manured broken land rather than in normal ploughed lands. The larvae are erratically distributed in lands and experiments on larval movement suggest that this is mainly due to concentration of the larvae at discrete concentrations of organic matter in the soil. The temperature and moisture condition of the top 3" of soil are found to be those which attact the larvae. It is suggested that tho larvae prefer and move to soil which contains the lowest amount of moisture which keeps the soil air spaces saturated. lt appears that the preferred temperature decreases with increasing soil moisture content and it is suggested that this is due to the respiratory requirements of the larvae. Soil pH, compaction and fertiliser content and the presence of plants do not appear to influence larval movements. A theory is developed concerning the mechanism of movements in the soil and it is suggested that, in the absence of a continuous gradient, the speed but not the direction of movement is influenced by conditions to which the larvae are sensitive. Evidence in support of thie theory is given. Studies on the survival of larvae at different soil moisture contents and temperatures show that conditions in the top 3" of soil are not likely to be lethal in spite of the high temperatures and low moisture contents found there. The relation of whitegrub behaviour to agricultural problems is discussed. Other workers published evidence indicating that early ploughed lands were attractive to whitegrubs; this is shown not to be the case and the previous evidence is re-interpreted. Such lands tend to contain concentrations of whitegrubs round the borders. The reason for this is discussed and it is suggested that lands should be ploughed early to confine whitegrub infestations in this manner. Soils low in fertility through repeated cultivation are commonly believed to contain more whitegrubs than virgin soil. However, behaviour studies suggest that it is the activity and not the size of the population which is affected by soil fertility. The time at which tobacco is planted is known to determine the extent of subsequent whitegrub damage. The reason for this is to be found in the life cycle of whitegrubs and the results of an experiment on time of planting in relation to whitegrub damage are given. Some insecticides are shown to be more repellant than others to A. opacicollis larvae and the influence of this fact on the assessment of soil insecticide effectiveness in the field is discussed. Reference is made to a method developed by the writer for the determination of insecticide effectiveness under the conditions of erratic whitegrub distribution which normally occur.
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  • Date Issued: 1954
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