Tanganyika Territory Research Articles

Colonial rodent control in Tanganyika and the application of ecological frameworks

ABSTRACT At the end of the 1920s, Tanganyika Territory experienced several serious rodent outbreaks that threatened cotton and other grain production. At the same time, regular reports of pneumonic and bubonic plague occurred in the northern areas of Tanganyika. These events led the British colonial administration to dispatch several studies into rodent taxonomy and ecology in 1931 to determine the causes of rodent outbreaks and plague disease, and to control future outbreaks. The application of ecological frameworks to the control of rodent outbreaks and plague disease transmission in colonial Tanganyika Territory gradually moved from a view that prioritised 'ecological interrelations' among rodents, fleas and people to one where those interrelations required studies into population dynamics, endemicity and social organisation in order to mitigate pests and pestilence. This shift in Tanganyika anticipated later population ecology approaches on the African continent. Drawing on sources from the Tanzania National Archives, this article offers an important case study of the application of ecological frameworks in a colonial setting that anticipated later global scientific interest in studies of rodent populations and rodent-borne disease ecologies.

The East African contribution to the formalisation of the soil catena concept

The concept of the soil catena was first explicitly formalised by Geoffrey Milne and his colleagues in East Africa in the 1930s. It has been widely adopted and applied in soil survey and continues to be of great value in soil and other field sciences The concept characterises widespread patterns in which distinctive associations of soils and vegetation are consistently located in specific slope positions. The formalisation of the concept in an area well outside the mainstream of soil research appears to have been due to the combination of highly visible recurrent patterns of red slope soils overlooking dark valley clays in East Africa’s extensive savannahs, together with a group of receptive and collaborative soil scientists working in a supportive institutional environment. The concept is often attributed to Geoffrey Milne, the group’s coordinator, but we show that several colleagues and friends also contributed. We summarise some of the early soil catenas characterised by Milne and his colleagues in Uganda, Kenya and Tanganyika Territory (now Tanzania). Even at the beginning, it was appreciated that the catena was not universally applicable and that heterogeneity of parent materials can override catenary patterns. The catena was quickly and widely adopted in soil science, and this diffusion has led to some broadening of the definition, and several types of soil pattern are now designated as catenas. The concept has also spread beyond soil science and is used by ecologists, geomorphologists and hydrologists amongst others. It continues to be a paradigm of great explicative and educational power in soil science and ecology.

Population censuses and changes in housing quality in Dar es Salaam, Tanzania

In spite of efforts by the British colonial government to improve the social welfare of Tanganyika Territory’s African residents, its housing policy was inadequate. It constructed too few homes and provided those homes with few urban amenities such as electricity, piped water and sanitation. The coming of independence to Tanganyika did not end those policies, so housing shortages increased and service provision continued to lag behind population growth. This paper uses four postcolonial housing and population censuses – from 1967, 1978, 1988 and 2002 – to track changes in housing quantity and quality. It demonstrates that some small improvements in quality have been realized but that many problems remain, especially in the prevalence of pit latrines and increasing reliance on water vendors.

The domestic (water) buffalo in mainland Tanzania

Tanzania had almost 18 million head of cattle – the third largest population of this species in Africa – in 2004 (FAOStat 2004). It also has relatively large populations, at 16 million head for the combined species, of goats and sheep. Donkeys are important in some areas for transport. Poultry include domestic fowl, ducks (mainly of the Muscovy type), Guinea fowl, pigeons, geese and turkeys. Horses (of which there have never been more than a few hundred in the country at any time) and pigs (mostly introduced by missionaries in the early 20th century) are minor species. The animals in the foregoing list can be considered as “indigenous” livestock. The domestic or water buffalo Bubalus bubalis is definitely an “exotic” species. An account of buffalo presence and performance or use in what was formerly the Britishadministered Tanganyika Territory and is now the mainland portion of the United Republic of Tanzania is the subject of this paper.

Chikungunya Fever, Mauritius, 2006

To the Editor: When an outbreak of chikungunya fever swept across several Indian Ocean islands in 2005 and 2006, the international public health community’s attention was drawn to chikungunya virus (genus Alphavirus, family Togaviridae). Among those areas affected was the Republic of Mauritius, located ≈900 km east of Madagascar, which has an estimated population of 1,250,000 and comprises the main island of Mauritius (area ≈1,865 km2) and several outlying islands including Rodrigues (≈180 km2). Mauritius Island had an initial outbreak of ≈3,500 suspected cases of chikungunya fever from April through June 2005 (1). With the onset of the drier season of winter, transmission of the virus subsided, but increased again during 2006. An outbreak began on Rodrigues Island in February 2006. The intensity of chikungunya fever outbreaks on Mauritius and Rodrigues Islands led us to explore the extent to which these outbreaks might have contributed to overall death rates. Chikungunya virus is transmitted to humans primarily by the bite of infected Aedes spp. mosquitoes. Aedes aegypti was effectively eliminated from the island of Mauritius during a malaria control campaign from 1949 through 1951 (2). However, A. albopictus is widely distributed on the island in rural and urban habitats (3); thus, A. albopictus may be the most likely vector for chikungunya virus. Common peridomestic breeding places in Mauritius include small pots and vases (used to decorate the outside of homes) and discarded rubber tires (3). Chikungunya fever was first recognized in 1952 after an outbreak on the Makonde Plateau of Tanganyika Territory (4), currently part of Tanzania. The word chikungunya is from a local dialect that translates to “that which bends up” in reference to the stooped posture often seen in patients with severe arthralgia (5). Human infections with chikungunya virus are associated with sudden onset of symptoms including headache, fever, rash, and muscle and joint pain (5). Before the outbreak in the Indian Ocean islands, deaths had not been associated with infections. However, Reunion Island reported >200 deaths during the 2006 chikungunya epidemic (January–April 2006) (6), and India conservatively estimated 1,194 deaths since the virus reemerged in December 2005 (7). To determine whether a similar situation occurred in Mauritius, we compared expected number of deaths with observed number of deaths and estimated number of chikungunya cases from January through December 2006. Crude death rates (CDRs) and number of deaths were obtained from the Annual Digest of Statistics 2005 and 2006 (8). We calculated expected number of deaths for each month in 2006 by multiplying mean CDR (per 1,000 midyear population) of each month for the previous 10 years (1996–2005) by midyear population for 2006. Estimated number of cases of chikungunya fever in 2006 for the Island of Mauritius was obtained from the Chikungunya Unit of the Ministry of Health and Quality of Life and includes both suspected and confirmed cases. A case was considered suspected if the patient had >2 of the following 3 symptoms: fever, rash, and joint pain. Cases were confirmed by cell culture. CDRs for the Republic of Mauritius ranged from 6.7 to 7.0 during 1996–2005 (mean 6.8) but increased to 7.3 in 2006, which represented a 4.3% (95% confidence interval [CI] 2.2%–8.5%) increase from 2005 (CDR 7.0). According to the 2006 midyear Population and Vital Statistics Report for the Republic of Mauritius (8), the number of deaths from January through June 2006 increased by 16.7% (95% CI 11.0%–23.5%) over the number of deaths in 2005, and 19.8% (95% CI 13.5%–26.9%) more deaths occurred among elderly persons (age >60 years). These numbers include all potential causes of deaths. However, increased CDRs occurred only during the months of the chikungunya fever epidemic on Rodgrigues and Mauritius Islands. CDRs on the Island of Mauritius in March, April, and May 2006 were significantly greater than expected (p 80 in May (9). Figure Expected and observed numbers of deaths and estimated number of chikungunya cases on Mauritius Island. Asterisks indicate a statistically significant (p<0.01) difference between expected and observed number of deaths for the specified months. ... The increase in CDRs reported for the Republic of Mauritius during the chikungunya epidemic is similar to the findings reported for the neighboring island of Reunion (10). Excess deaths in Reunion and the Republic of Mauritius coincided with the epidemic curve of the chikungunya fever outbreak, which suggested an association between these 2 factors. No other events that may have negatively affected the health of persons living in the Republic of Mauritius in 2006 were reported. However, because information on cause of death is unavailable, studies are needed to confirm that the chikungunya fever outbreak contributed to increased CDRs in 2006.

Thyroid tumour with multiple metastases

Journal Article Thyroid tumour with multiple metastases Get access John Williamson John Williamson Medical Officer Tanganyika Territory Search for other works by this author on: Oxford Academic Google Scholar British Journal of Surgery, Volume 24, Issue 95, January 1937, Pages 624–626, https://doi.org/10.1002/bjs.1800249520 Published: 05 December 2005

"Practising hygiene and fighting the natives' diseases". Public and child health in German East Africa and Tanganyika territory, 1900-1960.

For reasons of population policy and missionary strategies, childcare was a relatively early issue of colonial medical policy and services in East Africa. The main challenge for the adaptation of biomedicine to the local situation proved to be not so much schemes for treatment or prevention, but rather the question of staffing. Education and employment of females, as well as social acceptance and keeping up professional standards of biomedically trained personnel, posed major obstacles to the implementation of governmental health policies. In addition to these obstacles, European prejudices about African disinterest in child health contributed to the feeling that limited progress had been made after 50 years of biomedical efforts to improve African child health.

(1535) Proposal to Conserve the Name Eugenia bukobensis Engl. (Myrtaceae) with a Conserved Type

The name Eugenia bukobensis has been consistently used for a well-known and widespread tree particularly frequent and often a co-dominant around the northern end of Lake Victoria in Uganda and Tanzania and extending from northeastern Zambia to western Zaire, southwestern Ethiopia and western Kenya. It is cited in all the relevant local literature, for example Engler in Die Vegetation der Erde 9, Pflanzenwelt Africas 3 (2): 733. 1921; Eggeling, Indigenous Trees of Uganda: 153. 1940; Hora, Check-Lists Forest Trees and Shrubs British Empire 5. Tanganyika Territory Part 1: 84. 1940; Brenan, Check-Lists Forest Trees and Shrubs British Empire 5, Tanganyika Territory Part 2: 377. 1949; Eggeling & Dale, Indigenous Trees of Uganda ed. 2: 272. 1952; White, Forest Flora of Northern Rhodesia: 302. 1962; Boutique, Flora Congo Belge, Myrtaceae: 25. 1968; Hamilton, A Field Guide to Uganda Forest Trees: 192. 1981; Friis in Fl. Ethiopia 2 (2): 75. 1996; Verdcourt in Kew Bull. 54: 47. 1999; Verdcourt in Flora of Tropical East Africa, Myrtaceae: 59 (2001). However, when Engler described Eugenia bukobensis he cited in synonymy E. cotinifolia Jacq. var. elliptica (Lam.) Bak. ex Engl. et Nied. (in Pflanzenwelt OstAfricas C: 287. 1895), which is based on Eugenia elliptica Lam. (Encycl. 3: 206. 1789), a species described from Mauritian material and not at all related to the plant from Bukoba in Tanzania. Technically the name E. bukobensis is, therefore, illegitimate and must be typified by the type of E. elliptica from Mauritius. There seems no doubt that Engler was referring back to a misidentification; his description is of a new species which had been misidentified in 1895 and he naturally drew attention to this. Unfortunately his method of doing so renders his own name illegitimate under the present Code. Conservation with a new type is therefore proposed here. In the protologue of E. bukobensis, Engler cited five Stuhlmann specimens which were all destroyed during World War II; I have therefore selected a specimen collected more recently just north of Bukoba as the conserved type. The tree is of ornamental value, mainly because of its beautiful white flowers and is sometimes planted as a live fence (Katende A.B. et al., Catalogue of economically important plants in Uganda. Botany Dept. Makerere University, Kampala, Uganda. 1998). Perhaps there is a great potential for developing this aspect as researchers in Uganda are seeking to encourage use of indigenous ornamentals. The fruits are widely eaten raw (Katende et al., Useful trees and shrubs for Uganda. Regional Soil Conservation, RSCU/SIDA. Technical Handbook Series 10, Nairobi. 1995; Bukenya Ziraba, R. The non-cultivated edible plants of Uganda. NAPRECA Monograph Series No 9. Addis Ababa, Ethiopia. 1996; Bukenya-Ziraba, R. Some non-cultivated edible plants of Uganda. In Timberlake, J. & Kativu, S. (eds.). African Plants. Biodiversity, Taxonomy and Uses. Proc. of the 1957 A.E.T.F.A.T. Congress, Harare, Zimbabwe, 1999). F. White tentatively sank E. bukobensis into E. capensis (Eckl. & Zeyh.) Sond. subsp. nyassensis (Engl.) F. White (Fl. Zamb.: 4: 190. 1978), but we do not think this is correct. Recent workers on the genus in southern Africa (cf. E. Retief in T. H. Arnold & B. C. de Wet, Plants of southern Africa: names and distributions. Mem. Bot. Surv. S. Afr. 62: 523. 1993) do not accept his work on the genus. There are no synonyms and the alternative to conservation would be to produce a new name which would be confusing and irritating to local workers seeing that the current name has been in use for over a hundred

Colonial Science and Ecological Change: Tanzania's Mlalo Basin, 1888–1946

East Africa's coastal mountains, island massifs jutting up out of the surrounding savannas, have a thirty-million-year natural history as biological refuges. Their slopes have been watered for millennia by the Indian Ocean monsoons and have fostered the evolution of a broad diversity of flora and fauna.1 African farmers have long sought out these climatic and botanical havens and developed around their water sources a sophisticated agricultural production system designed to mitigate the severe droughts which periodically plague eastern Africa. Although long-term settlement in the mountains caused environmental change, its character and scope has yet to be adequately explained. Nonetheless, over the past seventy years, colonial and postcolonial governments have moved to ameliorate what they have perceived as human-induced ecological stress. This article examines the early phase of the colonial debates over environmental degradation and its remedies in the Mlalo basin, an upland region in the West Usambara mountains of Tanzania. The policy discussions regarding Mlalo occurred in the context of a general crisis in colonial society between 1929 and 1940, during which colonial perceptions of agroecological decline and the economic pressures of depression challenged European colonial governments in Africa and Asia. In terms of ecological issues, worldwide concern over erosion in the American Dust Bowl resonated across East Africa, resulting in an official preoccupation with soil conservation. Tanganyika Territory's Mlalo basin came to be cited in the 1930S as one of several particularly striking manifestations of soil degradation and agroecological decline.2 When a food shortage known as njaa ya Chankola (Chankola's famine) struck between 1941 and 1946, the specter of human and environmental catastrophe justified colonial degradation scenarios, which in turn guided the colonial government's attempt between 1946 and 1949 to modernize husbandry via the Mlalo Basin Rehabilitation Scheme.3 Recent scholarship in the social sciences has raised a number of questions regarding the course and interpretation of environmental degradation in Africa and Latin America. Many of these studies cite the historical tendency of Western (or

Effect of Spacing, Roguing and Weeding on the Incidence of Rosette Disease of Groundnut with observations on the Aphid Vector, Aphis craccivora Koch.

osette disease of groundnut was first reported in Tanganyika territory by Zimmerman in 1907. Sundararaman (1926) reported the occur- rence of a virus disease of groundnut at Palur Agricultural Experimental Station, Madras State. He named it as clump disease'. Storey and Bottomley (1928) concluded that the 'clump disease' reported by Sundara- raman (1926) in Madras State was similar to rosette disease of South Africa. Rosette disease is one of the virus diseases affecting groundnut crop in Tamil Nadu. The incidence of the disease varies from 0-25 0%. A scheme was initiated at the Agricultural College and Research Institute, Coimbatore with the financial assistance of The Indian Central Oilseeds Committee and later of the Indian Council of Agricultural Research to study the various aspects of the virus diseases occurring in groundnut crop.

Malaria in Tanzania

Tanzania, previously Tanganyika Territory and German East Africa, has a long history of research in malaria going back to German times. The author of Malaria in Tanzania is well qualified to describe both the past and the present state of malaria in Tanzania since he has done much research himself into the archives and has worked since 1952 on malaria in the country.This book gives an account of the present state of malaria in all its aspects in the many ecologic zones in the country. The epidemiology and entomology of the disease in each area are described in detail, and the results of past and present methods of control described.Much interesting detail of the immunology of malaria is given. Many experiments of mass chemoprophylaxis are described, and there is a good account of the present state of drug resistance in the country.Many excellentmaps and tablesof epidemiologic data are included.

A method of controlled home treatment of pulmonary tuberculosis in Tanganyika

The organisation and administration of a home treatment scheme is described. The scheme provided part of a tuberculosis control system in a portion of Tanganyika Territory. The aim was to ensure that patients could not be ‘lost’ and were regular in taking their medicines. The scheme relied on a staff of tuberculosis home visitors and on the active co-operation of the patients' community leaders. The patients were actively persuaded to participate in their own cure. The results of treatment in a series of 100 patients with pulmonary tuberculosis and positive sputum smears originally admitted in 1957 are detailed. 95 patients remain; 2 have died from causes other than tuberculosis and 1 from tuberculosis; 1 had been ‘lost’ and another had left the country. The sputum was negative on smear examination in 94 of the 95, and 89 showed considerable general improvement. 80 showed considerable radiographic clearing and these included 31 whose x-rays showed virtual resolution of the lesions.

On Camallanus johni sp. nov., collected from Xenopus in Tanganyika Territory.

A number of male and female specimens were available for study. They were collected by my colleague Mr. J. McClelland who very kindly made them available for study.Description: The worm is very small with the largest diameter at the cephalic end and tapers down posteriorly and rather markedly so in the female worm (Fig. 4). The cuticle has fine striations. The bivalve buccal capsule has a number of longitudinal ridges of varying lengths. The number of these ridges are different for the male and female. The head is slightly tilted ventrad. There is a pair of tridents. The ventral trident is small and indistinctly branched. The dorsal trident is large and clearly trifid. The posterior part of the buccal capsule ends in six small projections (Fig. 1).

Observations on the Simulium neavei complex at Amani in Tanganyika.

The paper deals with two members of the Simulium neavi Eoub. complex found at Amani in the forest of the Usambara Mountains, Tanganyika Territory. They have already been described but are at present termed the Amani unhanded and banded forms, scientific names being witheld until the taxonomy of the whole complex is better understood.Some methods of study are described.Pupae of the unhanded form constituted a large proportion of the total number found on the common local crab, Potamon (Potamonautes) lirrangensis Eathbun, which amounted to roughly one pupa to seven crabs. This form predominated in the lower and more open parts of the drainage system examined. The adults were not seen to bite man. This and the banded form were found at a much lower altitude than any hitherto reported for the complex, probably owing to the particular nature of the local climate. Neither form was abundant.The larvae and pupae of the banded form, like the unhanded one, live externally on the crabs. The variability of wing size of the banded form is described. Observations were made on the internal anatomy of the adult with special reference to the ovaries in which the follicular relics are usually very large, indicating that the female probably bites soon after laying eggs. As in S. damnosum Theo. there is an easily recognisable class of old flies with clear Malpighian tubes. Nulliparous and parous flies have rather different biting cycles. The banded form bit man readily but only about five were taken per hour in good catching places and far fewer elsewhere.Human onchorcerciasis has been reported from Amani but is not known to do any harm there. The existence of the disease in the presence of rather small numbers of Simuliids is of interest in relation to a belief that S. neavei is a more efficient vector of onchocerciasis than is S. damnosum. Out of 359 banded females dissected 41·2 per cent, were parous and 12·8 per cent, of these were infected with nematodes, at least some of which were not Onchocerca volvulus.Taxonomy, the ovarioles and the Simuliid-crab association are discussed. The formation of the large follicular relics of the banded form is considered in relation to the history of the follicular epithelium before and after ovulation. The crab association is regarded as commensalism-, and it is suggested that the crabs benefit the Simuliids by carrying them a short distance to a suitable current and that they thus enable them to live in fast rivers and so extend their range.

The Black Rhinoceros is brought back to Ruanda

Thanks to the protection afforded it by the Belgian Government, the northern race of the white, or square-lipped rhinoceros, Ceratotherium simum cottoni, is increasing in the Garamba National Park of the Belgian Congo. This park was specially created in 1938 to preserve the species, whose numbers there were down to about a hundred individuals. They now probably approach 1,000. But the story of the black rhinoceros, Diceros bicornis, is very different. Once common in the savannahs of Katanga, but now exterminated there, it used also to exist in the east of Ruanda, notably in what is now the Kagera National Park. So, in 1958, bearing in mind its success with the white rhinoceros, the National Parks of the Belgian Congo decided to try to reintroduce the black rhinoceros into Kagera. This rhinoceros is still not rare in some parts of Tanganyika Territory, especially in Karagwe district, but that country is separated from the Kagera Park in Ruanda by the River Kagera itself.

Application of haemagglutination and complement-fixation techniques to the identification and serological classification of arthropod-borne viruses: Studies on Chikungunya and Makonde viruses

Two viruses, Chikungunya virus and Makonde virus, which were isolated at the Virus Research Institute, Entebbe, Uganda, during an epidemic in Southern Province, Tanganyika Territory, in 1952–1953, have been studied by means of the haemagglutination-inhibition, complement-fixation and neutralization tests. Chikungunya virus is shown to belong to Group A of the arthropod-borne viruses and to be more closely related serologically to Mayaro and Semliki viruses than to any of the other known members of the group. Makonde virus is shown to belong to Group B and to be serologically indistinguishable from Uganda S virus.

Metamorphism in Deep-Seated Zones of Transcurrent Movement at Kungwe Bay, Tanganyika Territory

Deformed rocks developed in zones where transcurrent movements took place during a late stage of the Ubendian orogeny are described from Kungwe Bay, western Tanganyika Territory. In areas where the regional metamorphism was still continuing, the mineral assemblages developed in the movement zones are the same as those developing regionally. Cataclastic textures characterize such movement zones. In other parts of the district, where the regional metamorphism had apparently come to an end, the zones of concentrated movement contain both mylonites and certain fine-grained deformed rocks which show no obvious cataclastic features. Some of the latter have textures recalling those of hornfelses and contain minerals such as garnet and hornblende which have remained stable during the deformation and have grown porphyroblastically. It is considered that these rocks result from deformation of the crust at depth, resulting in a local high-grade dislocation metamorphism to which heat released during the movements may...

Density Distributions of Hoppers of the Red Locust,Nomadacris septemfasciata(Serv.) (Orth., Acrid.), in Relation to Control by Insecticides

In continuation of a study of the process of swarm formation in the Red Locust,Nomadacris septemfasciata(Serv.), to enable rational plans for control measures to be made, the population distribution of about 44½ million hoppers of the Red Locust was investigated in an observation area of 1,052 acres in the Iku outbreak area of the Rukwa Valley, Tanganyika Territory, from 18th January to 24th February 1957. to see if the hoppers showed a tendency to concentrate, which would have the effect of producing, immediately after the last moult, adult swarms from hoppers that were originally more scattered. From 25th January onwards, the estimated population remained constant in numbers. Densities over 50 per sq. yd. were unusual and, taking any continuous infestation over one per sq. yd. as a band, the mean density of hoppers in bands was 15 per sq. yd. There was a tendency for such bands to become larger by fusion and for the area quite free from locusts to increase slightly but the number of dispersed locusts increased. There would therefore have been no advantage in withholding insecticide control in the hope of attacking denser and more economical targets. Nevertheless, such populations have to be controlled.In the Red Locust, under the conditions described, it seems probable that the behaviour of the young adults is most important in the formation of dense swarms, while in certain other species but not in the Red Locust, concentrated egg-laying and the behaviour of the hoppers are also important.Investigations are required on more economical enumeration of patchy gregarious distributions.

The Reproduction of the Red Locust, Nomadacris septemfasciata (Serv.) (Orthoptera, Acrididae), in an Outbreak Area

During the breeding seasons 1952 to 1955, samples of females of the Red Locust, Nomadacris septemfasciata (Serv.), were caught in the Rukwa Valley, Tanganyika Territory, and the ovaries classified according to egg length. Ovaries designated Class V were those regarded as containing eggs ready for oviposition. Population estimates and rainfall records were also taken.The data suggested that the eggs in the ovaries develop very rapidly, becoming ready to be laid about seven days after the start of development.The increase in weight of an individual female during ovary development is related to absolute size, and it was found that, during ovary development, the weight increases by approximately one-half.The most important factor initiating ovarian development seemed to be a drop in daily maximum temperature to below 36°C. The factors of high humidity and rainfall were of less importance but their influence is not fully understood. The possibility of change in length of day being an important factor in the initiation of ovarian development is discussed.The limiting factors for the number of egg-pods laid in a season are considered to be the dates of the drop in daily maximum temperature and of the drop or decline in parental population. The date of drop or decline in parental population seemed to be connected with the date of drop in daily maximum temperature.The percentage of females laying more than one egg-pod was calculated, and the resuJts were found to vary considerably from year to year, although the average of 1 pods per female agreed with past estimates. Also, the average period of 16 days between successive egg-layings agreed with past work.Drought, during the laying period, seemed to cause the females to retain their ripe eggs.The evidence tended to confirm the possibility of a Red Locust population being able to increase 100-fold in a single year.

Enumerating Populations of Adults of the Red Locust, Nomadacris septemfasciata (Serville), in its Outbreak Areas in East and Central Africa

SummaryA method is described of estimating the total numbers and frequency distributions of adults of the Red Locust, Nomadacris septemfasciata (Serv.), in outbreak areas of hundreds of square miles, based upon counting the numbers that fly up in a two-yard strip in front of a moving vehicle. The method has proved itself valuable for indicating both immediate and future requirements for killing the locusts, but it requires refining for some research purposes.By this method, the importance has been clearly shown of the process of congregation of scattered adult locusts in forming emigrant swarms that could start a plague. The locusts do not congregate but actually disperse just before laying eggs.The total population in part (189 sq. miles) of the North Rukwa Outbreak Area (a self-contained area of 253 sq. miles) in Tanganyika Territory has been followed for four years. There are indications that a small migrant swarm contains 5–10 million locusts, that a total population in the whole of the North Rukwa Outbreak Area of 20 million locusts is unlikely to yield a migrant swarm, but that 50 million locusts could readily do so.In 1953, after poor rains, no natural mortality was detected between July and October by the assessment methods described. In 1957, after good rains, natural mortality of 70–90 per cent. was revealed by the same methods, although the dry season was not fully covered by the assessments.