The writer took over the Shinyanga fly-rounds in November 1934 from Mr. W. H. Potts, Senior Entomologist, under whose charge they had been since June 1932. The Maswa fly-rounds were not taken over until April 1935, when some of them had been in progress for a few months.

The Shinyanga area, its climate, topography, game and vegetation, have been described by Mr. H. M. Lloyd (1935), by Mr. C. F. M. Swynnerton (1923 and 1936), and by Mr. W. H. Potts in an hitherto unpublished paper, and no further general account is necessary. Table I gives in summarised form a synopsis of the seasons. The Maswa fly-belt lies to the east of the Shinyanga belt, separated from it by the Sukuma Cultivation Steppe, and was, until recently, part of the main G. swynnertoni belt that stretches from the bottom of the Serengeti Plains to Arusha and Moshi. As the result of reclamation measures carried out by the Tsetse Research Department during recent years, this belt has been severed from the main fly-belt, and the south-eastern section of this severed portion has again been cut off from the remainder by clearings. In this small isolated block of some 150 square miles an experiment in the exclusion of grass fires as a control measure against the tsetse was initiated in 1934, and fly-rounds were started in that area in order that a control might be kept on the progress of the experiment. Owing to administrative difficulties the experiment had to be discontinued in mid-1935, but the writer decided to continue the fly-rounds and to increase them by two additional rounds in the hopes of producing information, complementary and supplementary, to that from the Shinyanga rounds. The results of the fly-rounds from these two areas appear to throw light upon the vegetational preferences of G. swynnertoni and form the subject of this paper.

When studying the biology of the house-fly or any other fly annoying to man and domestic animals with a view to practical control, it is obvious that a correct knowledge of the breeding-places of the species is perhaps the most important problem which the investigator has to solve. As to the common house-fly (Musca domestica, L.) it is generally held that this problem has been completely cleared up by several workers years ago, but recent observations in Denmark have convinced the writers that this is not the case. We have arrived at conclusions regarding the chief breeding-places of the house-fly differing from those generally found in text-books.

Our work has not been limited to Musca domestica, for we have as far as possible studied the breeding-places of other flies occurring in houses or connected with domestic animals, first and foremost the stable-fly (Stomoxys calcitrans, L.). The knowledge of the biology of the stable-fly in Europe is surprisingly meagre, though the practical interest of this species as a tormentor of cattle and horses and a possible vector of infectious diseases is generally recognised.

As our observations may be of some interest to workers in other countries we have collected them in this paper, which constitutes the third of a series containing the main results of our investigations into the fly problem started under the auspices of the Health Organisation of the League of Nations and the Danish Committee of Rural Hygiene and with the support of the Danish Ministry of Agriculture and several private funds.

Fruit-piercing Lepidoptera constitute an important problem in some parts of the world, such as Africa, Australia and India; they also occur in Ceylon, Fiji, Dutch East Indies, Indo-China, Japan, Malaya, Samoa, and South America.

In Sierra Leone, grape-fruit, orange (sweet), mandarine, tangerine and sweet lime, are affected in addition to cashew, mango, bread-fruit and jak-fruit; whilst in other countries apple, apricot, banana, fig, grape, guava, litchi, nectarine, peach, pear and pomegranate, have been recorded as other adult food-plants; it is noteworthy that in South Africa grape-fruit does not appear to be attacked. Available information regarding fruit-piercing species and their biology is meagre compared with that of many other groups of economic insects, and it is considered desirable to place on record observations made in Sierra Leone.

Difficulties in the way of the study of these insects are the lack of knowledge regarding (a) larval food-plants; (b) characters and habits of the larvae; (c) the breeding areas and possible migratory habits of the larvae; (d) the breeding areas and possible migratory habits of the adults of some species.

Unless otherwise stated this account applies to Njala, where there is a plot of budded citrus; the trees were planted in 1925-1927 and mainly consist of Late Valentia and Washington Navel orange, and Marsh and Foster grape-fruit. The sweet lime, mandarine and tangerine are about ten years older.

During the testing of finely ground pyrethrum flowers as an insecticide for the control of Antestia lineaticollis, Stål, in coffee trees, it was noticed that the various instars showed different percentage death rates under the same conditions. The experiment which is dealt with here was primarily designed to discover the minimum effective dose of powder per tree, and was carried out as follows.

A block of 1,700 coffee trees was divided into seventeen square plots each containing 100 trees. Nine of these plots were treated with pyrethrum powder at rates varying from about 1 gram to 5 grams per tree; all the trees in the same plot receiving the same amount of powder. Two days later 36 trees from each of these plots, comprising all the trees from the centre of the plots (the two outer rows of each plot not being used in case migration of the Antestia should have taken place from the adjoining control plots) were heavily drenched with a strong kerosene extract of pyrethrum in order to bring down all the Antestia remaining on the trees; these Antestia were collected separately for each tree, sorted into instars and recorded. This method of testing is described fully by Le Pelley (1934).

In each of the eight control plots five trees selected at random were drenched with the kerosene extract of pyrethrum and the Antestia obtained were recorded in the same way. It was found that the average number per tree of Antestia and of each instar present in each of these control plots, which were themselves evenly distributed through the whole block, was practically constant. It was therefore assumed that the numbers of Antestia and of each instar was the same for the plots treated with pyrethrum prior to this treatment, and the number of each instar found on the trees after treatment subtracted from this figure represented the number which had been killed by the pyrethrum powder.

This is an account of laboratory experiments made with the tsetse Glossina palpalis. The results deal mainly with the effects of climatic conditions, temperature and humidity in particular, on the metabolism and life-cycle. Some work was also done on the activity and behaviour of the fly, but this is very incomplete, though it shows the importance of the problem and the need for further study.

The work was done during a visit of just over a year to East Africa, in 1935-36, as Wandsworth Scholar of the London School of Hygiene and Tropical Medicine. I spent most of the time at the Human Trypanosomiasis Institute, Entebbe, Uganda, and also visited tsetse areas in Kenya and Tanganyika. I am grateful to all those who helped to make my visit profitable. Among others, to the Directors of Medical Services of the East African territories, in particular the Hon. W. H. Kauntze of Uganda, and many members of their departments. To Mr. C. B. Symes, Medical Entomologist, Kenya, and to Mr. W. H. Potts, of the Department of Tsetse Research, Tanganyika. I am especially grateful to Dr. H. Lyndhurst Duke, Director of the Human Trypanosomiasis Institute, for many kindnesses. Considerable assistance was received from Mrs. Helen Mellanby, who was working on allied problems at Entebbe. And mention must be made of the intelligent and conscientious help of my laboratory assistant, Omw. Bonaventure Semalwadde.

The mosquitos of the Australian region have been extensively studied from the taxonomic aspect, and a number of workers, including Taylor (1914, 1928, 1929, etc.) Mackerras (1926), Cooling (1924), and Hill (1922), have recorded in general terms the types of water in which the larvae of various species are found. With the exception of the work carried out by Hamlyn-Harris (1927–28–30–33), however, no detailed studies have been made of the possible chemical, physical, or biological factors which may limit particular species of larvae to the special type of water in which they develop.

The most important pest species in the Sydney district are probably Culex fatigans, Wied., Aëdes (Ochlerotatus) vigilax, Skuse, Aëdes (Finlaya) notoscriptus, Skuse, Aëdes (Mucidus) alternans, Westw., Aëdes (Finlaya) alboannulatus, Macq., and in restricted localities Aëdes (Pseudoskusea) concolor, Taylor. Of these A. vigilax, A. alternans and A. concolor breed commonly in various concentrations of sea-water. A. concolor was selected for study owing to its strict limitation to a particular habitat, in the hope that some information might be gained as to the factors responsible for this limitation. In addition nothing has so far been published on the bionomics of this species, which is a particularly interesting one from the ecological and physiological aspects. A discussion of the general position with regard to mosquito ecology is hardly necessary here, since numerous authors have given excellent summaries and bibliographies up to the time of publication of their work, and original papers are appearing at frequent intervals. The majority of the work on mosquito ecology, with certain notable exceptions, has so far been carried out by means of water analysis (both chemical and biological) and field observations, correlated with the occurrence of different species of larvae. While it is recognised that any ecological generalisations, if they are to be accepted, must agree with the observed conditions in the field, nevertheless laboratory experiments, in which a single factor only is varied, should yield considerable information. It is mainly along these lines that the present investigation has been commenced. While the information so far obtained as to the factors limiting the occurrence of A. concolor has been largely negative, still it is hoped that the data obtained are of sufficient general interest to warrant publication. The work will be continued if possible over a number of years.

In 1933, the late Dr. Drysdale Anderson made a series of laboratory experiments at Onitsha, Southern Nigeria, to study the mosquito larva-killing properties of a number of mineral oils and of some mixtures of these oils. For the experiments he used fresh fourth instar larvae of Anopheles costalis, Giles, which is the most common malaria-carrying species in Nigeria; these larvae he obtained from two temporary pools in the bush, which produced large numbers of larvae in wet weather but dried up after a period of 48 hours without rain.

For his experiments Dr. Anderson used plates marked at a diameter of 19-5 cm. (giving a depth of fluid of 2-5 cm.) with 20 to 30 larvae for each plate and one observer for every 3 plates. An experiment consisted of an average of 200 larvae. The oil was applied by discharging 0·65 cc. from a pipette.

It was suggested that confirmatory experiments in the field were required to check the results of these laboratory experiments. This led to the methods described below being devised by us for testing the efficiency of larvicides under conditions as nearly natural as practicable.

To ensure comparability of results we dug our own breeding-pits, each approximately 2 feet by 2 feet square, on low-lying ground where the ground water is very near the surface. The pits were made of such a depth as to contain 8–12 inches of water and are kept under observation for breeding, and when this occurs its intensity is recorded by measuring out a definite number of dips taken along the four sides of the pit and by counting the larvae captured.

For this “dipping” we made our own rectangular dishes of zinc sheeting with sloping sides 2 inches from rim to bottom, 9 inches by 5½ inches in area at rim level, and 8 inches by 4½ inches in area at the bottom. In practice, such dishes collect about 30 fluid ounces at each complete dip.

The bionomics of sandflies (Phlebotomus: Psychodidae) have been studied mainly in relation to the diseases they transmit. Comparatively little experimental work has yet been undertaken on the physiology of Phlebotomus in the laboratory. In the present paper experiments are described on the thermal limits of Phlebotomus, on the influence of temperature and humidity on the length of life of adult sandflies and on the loss of water in larvae and pupae. The problem of loss of water in sandflies is of particular interest, since adjustment to a varying humidity under natural conditions appears to be an important factor in the transmission of diseases by these insects.

For the study of sandflies in the laboratory an ample supply of insects raised under uniform conditions is required. In a previous publication (1934) a breeding method has been described which provides any desired number of sandflies. If overcrowding of the breeding pots is prevented the flies are relatively uniform.

The species used in the experiments was Phlebotomus papatasii, the common sandfly of the Mediterranean, which is the most suitable species for laboratory work; it is comparatively easy to breed and to handle and feeds readily in captivity. The sandflies used in the experiments were bred from females caught in October in Jerusalem. The pots containing the larvae were wrapped in moist cottonwool and survived the transport to London without any damage. The work was commenced, and parts of it completed, in the Department of Entomology, London School of Hygiene and Tropical Medicine, where I held the Avebury Studentship. It is a pleasure to acknowledge the help received from Professor P. A. Buxton and the valuable collaboration of Mr. J. D. Gillett. The work was completed in Jerusalem.

The genus Nysius, Dallas, as pointed out by China (1934), is in some respects the most cosmopolitan of all Hemipterous genera. Two species have been previously described from Australia, of which one, Nysius vinitor, Berg., occurs in every State of the Commonwealth. The other species, Nysius clevelandensis, Evans, is known only from Queensland. Below is described a third species which is apparently confined to Tasmania.

The work which is described in this paper was undertaken owing to the conflicting results of standard fumigation practice in Palestine as it existed up to 1932, so that it became evident that the response of the Black Scale to Palestine conditions called for investigation.

Owing to the difference in climate between the Northern Coastal Plain and the Jordan Valley a series of parallel investigations had to be initiated, with the interesting results which Dr. Schweig and Mr. Grunberg have set forth.

There seems little doubt that the growers in the Jordan Valley will have to change from summer to winter fumigation and that in Acre Sub-District even if the double fumigation now under trial is not practicable (and there is no reason wh y it should not be) fumigation will have to be completed by the end of July—otherwise the fruit of the last fumigated groves will be infested before the gangs can reach them. With regard to biological control, this would be pf more value for keeping down the Black Scale population on alternative hosts, such as Eucalyptus groves and roadside trees. Negotiations for the importation of Comperiella bifasciata are in progress, and if this proves possible it will be given a trial in the Jordan Valley and the Coastal Plain.

It is unfortunate that the pressure of other demands on the time of a small staff precluded the investigation of the behaviour of the Black Scale in Jaffa Sub-District, but general observations show that it tends to react more in the manner of the Jordan Valley race than of that of the Northern Coastal Plain.

All the orange-groves between Jaffa and Haifa are heavily infested with Aonidiella aurantii, and it will be interesting to see, in view of the observations on mutual tolerance contained in this paper, whether Black Scale spreading from Jaffa will drive out the Red Scale or fail to make headway agaipst it.