In an attempt to isolate yellow fever virus from Aëdes (Stegomyia) africanus, Theo., an intensive series of catches was carried out during 11 weeks of 1945 in 2 forest areas in Bwamba County, Uganda. Most of the work was carried out on platforms in trees during the sunset period, since the main biting activity of A. africanus occurs in the forest canopy just after sunset. Virus was not obtained during the course of this work.

The results confirmed that A. africanus is the dominant arboreal Culicine of the sunset period. In catches carried out actually in the canopy it formed 69 per cent. of the total Culicines taken.

Experiments are described in which the concentration-time-mortality relationships with certain insects were investigated for the insecticides DDT and γ-BHC, the insecticides being used in film form. Adults of Tribolium castaneum, the larvae of Plutella maculipennis and adults of the Aphid, Macrosiphoniella sanborni, were used as test insects. T. castaneum proved the most suitable insect for experimental laboratory work on films, since it can be kept in continuous contact with them without difficulty.

A description is given of the techniques employed for T. castaneum and also for the other insects which are able to progress on perpendicular glass surfaces. Techniques are described for experiments in which attempts were made to eliminate as far as possible the fumigation effect of γ-BHC and to differentiate it from that of direct contact. The fumigation effect of this compound is considerable and it appears impossible to eliminate it entirely.

With T. castaneum the characteristic curves connecting log. concentration with percentage mortality varies with time of exposure, from horizontal lines showing on the one hand zero toxicity and, on the other, complete mortality at all concentrations. Sigmoid curves are represented between these limits. The average survival period of T. castaneum adults gradually decreases with the strength of poison in the film.

The surface upon which toxic films are deposited was shown in preliminary experiments to have a definite bearing upon their effectiveness. Waxed surfaces showed least toxicity, and amongst a few leaves used Geum gave the highest and water lily, at lower critical concentrations, the least effect. High concentrations on water lily were little different from others in toxic action.

Examination of Newstead's specimen has confirmed the substantial accuracy of his description and drawings, with the exception of the genital pump. The form of the aedeagus alone leaves no possibility of confusion with P. perniciosus, of which there has been available an adequate series of Italian specimens for comparison. The view of Adler and associates that the sixth spines are aberrant is thoroughly reasonable. P. mascittii is therefore an easily recognizable species, as to the male, from existing descriptions and drawings, and represented by the sole known cotype in the British Museum, which is hereby designated the lectotype.

The question of the distinguishing characters of the female is bound up with the whole matter of the identity of P. mascittii and P. larroussei. The evidence already published, involving both males and females, certainly constitutes a strong case for the identity of these two species. There may be cited: (a) the character of the wing venation which seems to be constant in both sexes; (b) the general agreement as to the male genitalia; (c) the fact that one of Saccà's specimens was caught within a few hundred metres of the type locality and the others in the same city. In the absence of any contrary evidence there is no reason to doubt the soundness of the view shared by Saccà and Parrot that these two species are identical.

Formulations of DDT have been applied to standard mud blocks. Toxicities to Glossina palpalis and Aëdes aegypti, and the proportions of insecticide recovered from an outer layer of approximately 0·1 mms. thickness have been compared.

Absorption of DDT in oil solutions was considerable, and amounts recovered from the outer layer were only from 8–19 per cent, of the total dosage applied. Adsorption of the insecticide from the oil on to mud occurred. There was some correlation between the capillary rise of the solvent and the extent of absorption. Toxicities of the blocks to test insects were low.

Using concentrations of 2 per cent., 5 per cent, and 10 per cent. in power kerosene, there was no increase in the proportion held on the surface. Application of excessively heavy dosages increased the amounts in the outer layers but there was a trend towards greater absorption, and therefore to greater waste, at the high dosages. Repeated applications similarly built up a larger dosage in the outer layer but did not increase the proportion there.

Emulsions were intermediate between solutions and wettable powders as regards absorption and toxicity.

Up to 77 per cent, of the insecticides applied as wettable powders was recovered from the outer layer, and toxicities were correspondingly high. When benzene hexachloride wettable powder was used there was rapid loss of benzene hexachloride from the surface by volatilisation. After fifteen days the dosage had decreased considerably and the percentage in the outer layer had fallen from over 70 per cent, to 20 per cent.

Loss of DDT by penetration of the carrier oil through the leaf cuticle may occur when an oil solution is sprayed on to vegetation. The extent of penetration varies with different plants.

There is an indication that small amounts of DDT are transferred from the inside of treated leaves to other untreated parts of young coffee and Avocado pear plants.

Deposits of DDT on leaves exposed to ordinary climatic conditions remained toxic to tsetse flies for a longer period when applied as an emulsion than as an oil solution. Deposits from a water suspension of a wettable powder were washed off readily by rain.

There is some evidence that continuous exposure to sunlight produced some chemical change in, and reduced the toxicity of, DDT deposits applied to glass plates as a solution in kerosene.

A small reclamation experiment staged in the coral rag thicket under unfavourable conditions proved successful in eradicating Glossina austeni and G. brevipalpis and in virtually eradicating G. pallidipes. Applied with adequate protective clearings, it is thought that the method may prove entirely successful in eradicating G. pallidipes as well as G. austeni and G. brevipalpis.

Under both dry and wet season conditions traps proved quite ineffective.

A method is described for studying the life-cycle of Melophagus ovinus. The female ked matures in 6 to 7 days and the male in 10 to 11 days. Copulation takes place 16 hours after emergence and the first pupa is deposited by the female about 13 days after its emergence. The second and successive pupae are deposited at intervals of seven to eight days. The pupal stage covers 20 to 26 days (an average of 22·5 days for 28 observations). The life-cycle is completed in 33–36 days. Experimental conditions did not affect the duration of the various stages observed in the life-cycle.

An investigation of the periodic fluctuations in the infestation of a flock of Welsh sheep showed that the degree of infestation is influenced by the transference of keds between the sheep. Before lambing, keds are transferred from hoggs to two- to three-year old ewes and, after lambing, from ewes to lambs. The peak infestation of ewes and hoggs occurs before lambing. The maximum infestation of lambs occurs before shearing. At shearing the majority of adult keds and pupae are removed with the fleece. Adults surviving after shearing are killed at dipping. Depending on the nature of the dip, re-infestation results from pupae hatching in fleece or by the transference of keds from infested sheep coming into contact with the dipped flock. Keds disappear from the fleece through being devoured by the sheep, by the activity of insectivorous birds and through natural death. The transference of keds between sheep is achieved through contact and occurs readily when the ked is on the surface of the fleece. The vertical migration of the insect in the fleece is controlled by temperature and is not influenced by light.

The distribution of pupal and adult stages of M. ovinus in the fleece of lambs, hoggs and ewes is given. The position of attachment to the pupae is controlled by the depth of the fleece, deposition occurring on the wool fibres at a point where the temperature is suitable for their development. The age of the sheep influences the distribution of the ked, young sheep being more susceptible than older animals. In a flock, the higher infestation of hoggs compared to older ewes may be due to the higher initial infestation of the hoggs after dipping. Open fleeced sheep are more susceptible to ked infestation than tight fleeced sheep.

Records of oviposition by blowflies on test groups of sheep, over a five-year period, were examined for relation between the rate of oviposition per day and the conventional meteorological indices of daily weather conditions. There was a definite correspondence with the maximum shade temperature for the day. The relation was not straight-line, the slope changing at between 18 and 20°C. The association with the minimum temperature was not significant. Insolation, as measured by the difference between maximum temperatures in the sun and shade, was positively associated with oviposition.

The humidity indices—evaporating power of the air and the saturation deficit—and the ratio of the daily totals of rain and evaporation, showed a low correlation ; the rainfall correlation was barely significant. The association was in no instance statistically reliable.

The room used for housing a colony of Anopheles punctulatus punctulatus is described. Its main features were an insulation system to enable some degree of temperature control during the winter months, and eight windows to ensure that the room had good natural lighting.

The adults were kept in breeding cages, which were large enough to allow the insects to manoeuvre during mating and oviposition, and designed to ensure a high humidity and at the same time expose the adults to daily fluctuations in light intensity. Provision was made for easy access to the interior during feeding and management operations.

The essential feature of larval management was that the larvae were kept throughout their development as separate batches, representing daily age groups. During the first three days after hatching they were left in the dishes containing soil and water in which the eggs were laid. From the third day, they were reared in shallow glass dishes. They were fed with Farex at intervals throughout the day.

The biology of the Cerambycid, Quettania coeruleipennis, which is a serious pest of almond and pomegranate in Baluchistan is described. The larvae attack the top shoots and small branches, tunnelling downwards; the attacked branches ultimately become hollow and dry up.

The various stages are described in detail and their duration and seasonal history during the years 1943–1946 have been investigated. During these years, oviposition commenced between 7th and 18th May and ended between 22nd May and 3rd June; the incubation period of the eggs ranged from 12 to 19 days (average 15·9 days). Hatching of eggs started between 22nd May and 2nd June and ended between 10th and 20th June and the feeding period of the larvae ranged from 265 to 317 days (average 289·6 days). The prepupal period varied from 7 to 12 days (average 9·7 days). The first pupation during these four years took place between 2nd and 10th March and the last between 12th and 24th March and the pupal period varied from 25 to 36 days (average 30·2 days). Emergence of the adults began between 5th and 15th May and ended between 18th and 29th May.

Glossina pallidipes does not readily attack objects moving along the edge of vegetation forming its habitat; fewer tsetse attack under humid than Under dry conditions, but those that do seem to range further.

Parties of men moving out of heavily infested thicket did not carry tsetse far into the open. Few tsetses attached themselves to the men and these became gorged within a few yards of the thicket edge. Similar results were obtained when bait cattle were used.

Experimental catches in a glade showed, even during the humid season, an extraordinary reluctance on the part of G. pallidipes to approach a party moving through the glade even at so short a distance as 8 yards from the thicket, but further experiments showed that a party staying in the glade for a short time made a much larger catch.

A campaign to control the weed, Cordia macrostachya (Jacq.) Roem. & Schult. (Boraginaceae) by biological means is in progress in Mauritius (Williams, 1948). This hardy perennial shrub was accidentally introduced from Central America in the last decade of the nineteenth century. It is today a serious pest of nearly all land of agricultural value which is not intensively cultivated (Wiehe, 1946).

Green (in Stebbing, 1902) described a species collected by Stebbing at Dehra Dun in 1899 as Monophlebus stebbingi. The principal diagnostic character of this species was the presence of six fleshy tassels at the caudal extremity of the male (fig. 1, a). Green (in Stebbing, 1903) proposed the name Monophlebus stebbingi var. mangiferae for a form found on mango in the Shalimar Gardens near Lahore in which the adult male carried eight fleshy caudal tassels. Later (1908) he described material from the Shalimar Gardens on mango as Monophlebus stebbingi var. octocaudata.

The great increase, in recent years, in the number of contact insecticides has created a demand for methods whereby the content of active substance in samples of these insecticides may be estimated quantitatively in a simple manner. Such methods are important, because on the one hand the producer wishes to know if his product meets the necessary requirements and on the other hand the official services concerned with the control of insect pests must be able to test the fundamental value of commercial preparations. Moreover quantitative methods for the estimation of contact insecticides are useful for scientific research in this field.

The following is a description of a mosquito found to occur in the hills surrounding Tambunan Plain, North Borneo, whilst working with the Malaria Research Department, in 1939–42. It appears to represent a new variety of the Anopheles aitkeni type, which it is proposed to name Anopheles aitkeni borneensis.

The rapid spread of the single host arsenic-resistant blue tick, B. decoloratus, a transmitter of piroplasmosis and anaplasmosis, seriously affected a large and important cattle ranching area in South Africa.

Biological tests, using the laboratory technique described in an earlier paper, enabled the most effective “Gammexane” preparations to be rapidly selected from numbers of experimental dips. The technique was also employed as a supplement to chemical analyses of dip wash samples where only the total hexachlorocyclohexane and not gamma isomer was estimated. Twenty-thousand adult female ticks were used in these in vitro tests. Oil emulsions seemed more active than dispersible powders or pastes, but all tests indicated that 50 parts per million “Gammexane” should satisfactorily control the tick in the field.

Laboratory tests with larvae of the blue tick showed that “Gammexane” had a persistent action and was very toxic to this stage of the tick. Excellent control oflarval ticks could be anticipated in the field.

In vitro tests indicated that “Gammexane” was effective against the two- and three-host ticks, R. evertsi, R. appendiculatus, A. hebraeum, H. silacea and Hyalomma spp., but hand dressing and shorter dipping intervals might be necessary to control these ticks in the field. The sheep paralysis tick, I. pilosus, seemed to be resistant to “Gammexane” but was readily killed by arsenic.

Bis(bis dimethylamino phosphonous)anhydride is shown to be a systemic insecticide when sprayed on the leaves of numerous plants. The translation of it from one part of the plant to another, over distances varying from the thickness of a leaf to three feet, was shown with Aphis fabae, Myzus persicae, Brevicoryne brassicae, Macrosiphoniella sanborni and Pseudococcus citri.

Plants treated with it are shown to be toxic to 14 Aphid species, one Aleurodid, one mealy-bug, two Jassids and two species of red spider.

It is not found to be toxic to non-plant-sucking insects, notably predators and parasites. It is, therefore, a selective insecticide for the control of Aphids, and field experiments have shown that treatment with it gives plants prolonged toxicity to Aphids and allows the parasites and predators to keep in check any survivors or newly arrived individuals.

Non-selective organic phosphorus insecticides such as Parathion, Paraoxon and HETP give a high mortality, but the Aphid population builds up again very rapidly after treatment with them, leading, in many cases, to a heavier infestation than before.

Plants treated with bis(bis dimethylamino phosphonous)anhydride, on the other hand, keep free from Aphids for prolonged periods (2 to 5 weeks depending on the species of Aphid, the stage of growth of the plant and its physiological condition).

The term “Bush Locust” is defined.

The synonymy and known distribution of Phymateus aegrotus are given and previously published records of its occurrence are reviewed.

The occurrence of hopper-bands, and of adults, in East Africa for the years 1938–47, inclusive, is outlined.

P. aegrotus and other species of the genus are normally unimportant economically as adults, but the hoppers form bands after the manner of, though on a much smaller scale than, true locusts. Outbreaks of these hopper-bands appear to be sporadic but they are sometimes destructive to crops.

P. aegrotus has usually been of only local importance as an agricultural pest but areas in which the crops have been damaged are noted. Among wild host-plants there appears to be a preference for Euphorbiaceae although the hoppers are more or less polyphagous.

Other East African species which form hopper-bands and which are known to attack crops are mentioned.

The life-history of P. aegrotus is described so far as it is known, and observations made by Dr. H. B. N. Hynes on the closely related species, P. pulcherrimus, in Ethiopia are also recorded.

Reflex actions in Phymateus species, including such phenomena as autohaemorrhage and colour display by the adults when alarmed, are noted and the literature on the subject is reviewed.

Observations are made on hopper behaviour and band-size of P. aegrotus. The latter is usually only a square yard or two in extent but bands up to 25 square yards in area have been observed by the author and there are reports of even larger ones. These bands are very dense both when marching and when stationary (60–80 finalinstar hoppers per square foot). Notes on areas of infestation are also given.

In most cases it is sufficient to beat out the bands with branches. Poison bait and dusting with 7 per cent, di-nitro-ortho-cresol are also successful.

Detailed descriptions of the coloration of final-instar hoppers of P. aegrotus and the other East African Phymateus species discussed are given. Keys for the identification of these hoppers and of the adults of the four species, P. aegrotus (Gerst.), P. pulcherrimus I. Bol., P. viridipes Stål and P. purpurascens Karsch (for all of which standardised English names are proposed), are also included.

The spreading of larvicidal oils is hindered by the presence of natural films upon the surface of standing water. The film pressure, which measures the resistance offered to the spreading of oil, can be determined in the field by a simple method depending on the use of standard spreading liquids.

It seemed reasonable to suppose that by making tests on the waters at many different places it should be possible to estimate the optimum spreading properties required in a larvicidal oil before its distribution began in a particular district. An attempt to do this was made in a part of the Gold Coast in 1944 and the investigation showed that in that region, and at that time, the spreadability of an oil with spreading pressure equal to 30 dynes/cm., approximately, would have been adequate for larvicidal purposes. It was also found that the natural films, which could be either visible or invisible, were of two physical types distinguishable as “uniform” and “non-uniform” according to the observed variation of the film pressure at a single site.

Many female Anophelines wander into huts at random, possibly for shelter, and afterwards feed upon any suitable inhabitants.

This random wandering can be eliminated by pyrethrum spraying, and the acute discrimination of those Anophelines which enter primarily for food can then be demonstrated.

In sprayed huts there was a close relation between the number of men sleeping and the number of Anophelines attracted. The proportions attracted by 3 men and by 1 man were, for A. melas, 2·72; 1: A. gambiae, 2·38; 1: A. funestus, 2·28; 1. Discrimination was reduced at one period by the masking odour of cut and withering bush.

There were marked fluctuations in the attractiveness of individuals to Anophelines. On several occasions one or other of the men used as bait suddenly became much more attractive than his fellows, and remained so for several days.

The removal of a village increased by only 25–50 per cent. the proportion of mosquitos caught in two huts which were allowed to remain on the village site. This result indicates that most of the mosquitos which had infested the village had been attracted from a distance by the scent, and had not merely arrived in the vicinity of the village by chance.

Tambunan is an elevated and isolated plain in the interior of North Borneo, occupied by irrigated paddy cultivation, surrounded by jungle-covered hills, and inhabited by a primitive native population subject to severe malaria.

The Malaria Research Department of North Borneo carried out surveys in this locality during 1939–42 for larval and adult Anopheles as part of an investigation into the causes and control of malaria in Borneo. The main findings of this work, and the incrimination of A. leucosphyrus, Dön., as a vector of malaria, have been described elsewhere (McArthur 1947), but brief accounts are given below of the habits and characteristics of the Anopheles in the locality.