In March 1957, an outbreak of human sleeping sickness was discovered in the South Mamprussi District of northern Ghana. Temporary measures were initiated at a few villages to provide protection, at water-holes on streams, against attack by the two prevalent species of tsetse, Glossina palpalis (R.-D.) and G. tachinoides Westw., until clearings could be made.

These measures consisted of grass-mat passages approximately 8 ft. high, extending from about 75 yd. from the stream down to and around the waterhole. At the water-hole, there was a gap of about 1 ft. between mat and water.These passages were found to be successful in excluding tsetse fly. This suggests several points of interest about G. palpalis and G. tachinoides: that at that time of year and in that type of vegetation, they do not rest higher than 8 ft. above ground; that the portions of human anatomy that showed beneath the matting did not attract the fly; and that these species depend on sight for hunting rather than on smell.

The cost of this matting was negligible as compared with the cost of routine clearing, and this method of temporary protection was considered successful for its purpose.

In the lower South-East of South Australia, adults of Aphodius tasmaniae Hope, which is an economic pest of improved pastures, emerge from the soil 2–3 days after rain has fallen in summer. The females may lay two batches of eggs. The first batch (about 35 eggs) is developed at the expense of the fat-body and is laid 3–6 days after emergence; a second batch (about 20 eggs) can be developed and laid after the female has fed on dung.

The beetles are crepuscular and fly after sunset if the weather is suitable for flight. The first batch of eggs may or may not be laid before flight, depending on the weather. Until the fat-body is largely depleted, beetles fly with the wind and are attracted to lights, but after that stage has been reached they fly upwind to dung and are not attracted to lights. After feeding on dung for a few days the females become gravid again, and apparently change their responses to light and wind once more. The distribution of larvae in the field suggested that adults aggregated and laid eggs in specific places. The factors which promote aggregations of adults were therefore studied.

The survival-rate of the females and the number of eggs they laid in two soils, a sand and a clay loam, were related to the ‘available water’ in soil as measured by the pF scale. Females survived in largest numbers and laid most eggs in the range of pF 2·8–3·2 in both soils. Similarly, when given a choice of a number of water contents in soil, beetles aggregated in largest numbers within the range 2·8–3·2 in one soil and pF 2·8–3·5 in another. In the latter soil, however, the pF values that were tested were more widely spaced, and it is suggested that the combined data are only intelligible if there was an optimum range of pF within the vicinity of 2·8–3·2 in both soils. These and other experiments indicated that moisture in soil was the major factor capable of' promoting aggregations of adults.

When water was not limiting, aggregations of beetles occurred on loose as opposed to compact surfaces. However, ‘shelter’ (dry grass stems broken off the parent plant, dung, etc.) was capable of promoting aggregations even if the soil underneath ordinarily inhibited burrowing. Aggregations of beetles also occurred on surfaces into which other beetles had previously burrowed; this was probably due not to any attraction of beetles to other beetles, but to loosening of the surface soil by the original beetles, which permitted later arrivals to burrow rapidly.

It is probable that the patchy distribution of larvae in the field is due to the aggregation of the adults in the field mainly in relation to moisture in soil, type of surface and shelter. It is also suggested that aggregations of larvae that occur around conspicuous objects, such as trees, result from beetles colliding with these objects by chance when they are flying after dark, dropping to the ground and burrowing into the soil to lay eggs there.

The genus Heterococcus was erected by Ferris (1918) for a new species. H. arenae Ferris, having 9-segmented antennae, a denticle on the claw and with the normal trilocular pores replaced by quinquelocular pores. Other species were added later and Morrison (1945) discussed the genus at some length and described in detail three other related genera.

Distortion, a severe stunting and deformation of plants of guineacorn (Sorghum vulgare) in Northern Nigeria, has been shown to be caused by Heterococcus nigeriensis Williams feeding on the plants.

The symptoms are striking; affected stems are much shorter and wider than normal and leaves are mis-shapen, with irregularly divergent veins and white tissue between the veins. Symptoms in the field vary from small patches of distortion on other normal plants to whole plants affected. The abnormal leaves of a plant with severe distortion are crumpled and remain rolled together. Growth of the plants virtually ceases if the mealybug infestation continues but, in the absence of mealybugs, affected plants recover and produce normal leaves.

Distortion has been found in the field, commonly on Sorghum vulgare, Zea mays and Cynodon dactylon, and once only on Pennisetum typhoides and Chloris pycnothrix, respectively, and has been produced experimentally on Z. mays, C. dactylon, P. typhoides, Triticum aestivum, Oryza sativa and Digitaria exilis by transferring mealybugs from affected guineacorn.

The rate of development and the egg-production of the Dermestid beetle, Trogoderma parabile Beal, at 30°C. and 60 to 70 per cent. R.H. and the effect upon larval development of the volume of food, the temperature and the relative humidity have been determined.

In 15 to 450 cc. of wheatfeed at 30°C. and 60 to 70 per cent. E.H., active adults are formed from eggs in a mean of 39 days (egg 6, larva 26, pupa 5 and pre-emergence 2). Males develop slightly more rapidly than females. On average, a female adult lives 8 days and 53 of her offspring reach maturity. The weekly rate of increase of a population of stable age distribution (A) is × l·7.

At temperatures between 17·5 and 37·5°C. (and at 70 per cent. R.H.) and at humidities between near 0 and 90 per cent. R.H. (and 30°C.) larvae can grow to a large size; but in 0·7 to 25 cc. of food some of these large larvae enter a facultative diapause, as a result of restricted space. Disturbance of the food increases the proportion of diapause larvae. The diapause larvae feed and moult intermittently. At 30°C. and 60–70 per cent. R.H., a period of seven weeks after hatching has been adopted arbitrarily to distinguish diapause and non-diapause larvae. Only a limited success was obtained in breaking the diapause, which is less readily broken than that of T. granarium Everts.

The limitations of the use of apparent density in estimating trypanosomechallenge are discussed, and it is concluded that such estimates should be based on the feeding portion of the tsetse population, its activity in relation to a given host, the total period of feeding activity (or parts thereof) as the unit of time, and the trypanosome infection rate.

A method of investigating the diurnal feeding activity of Glossina pallidipes Aust. in the late dry season at Eekomitjie, in the Zambezi Valley in Southern Rhodesia, is described. A black ox was tethered daily under a large tree from before dawn until after dusk. Only flies that engorged on the ox were caught; the time of capture and sex of each fly was recorded, and the fly then marked and released. Catches were made on 15 separate but not consecutive days between 21 October and 30 November, 1959.

Diurnal activity extended from 0445 to 1845 hr., there being a small earlymorning peak, reduced activity over the midday period, and a comparatively large evening peak. Climatic factors were recorded but no conclusions could be drawn about their separate effects on activity.

A population of Glossina swynnertoni Aust., at Shinyanga, Tanganyika, has been studied in respect of size and fat content of non-teneral males by monthly samples over a period of 13 years.

Flies are large from February to July and small from August to January, and this change in size suggests an effect of the wet season (December to May) and dry season (June to November) upon the parent females, allowing for the time-lag of two months representing pupal development and mean age of adult males at capture. Male flies have more fat in the rains and less in the dry season and it is possible that similar changes in the nutritional status of females are responsible for the observed size changes.

The correlation found in earlier work between the size of male flies in any month and saturation deficit two months earlier is confirmed, but reasons are given for rejecting a simple causal interpretation of this correlation.

Since 1951, there has been a progressive decrease in size of G. swynnertoni in the area studied, more especially as regards those produced in the dry season.

An apparatus and technique are described for handling, immobilising by suction, and individually dosing house-flies, Musca domestica L. The apparatus consists of a suction platform connected to a vacuum cleaner, a specially designed cage and a measured-drop apparatus. The suction platform consists essentially of a circle of terylene gauze, on to which the flies are drawn from the cage and held by suction during treatment. The cage can be made to contract, so that the flies may be crowded together near the special emergence hole through which they are to be withdrawn. The technique avoids the use of cooling and anaesthetics, which affect the metabolism of the flies, and is therefore especially suitable for measuring knockdown, although it can equally be used to estimate toxicity. Some factors likely to influence the results are examined and discussed, and an example is given of two experiments with house-flies, to show that the method gives reproducible results.

A method is described for the large-scale rearing of Pseudotheraptus wayi Brown, the Coreid causing immature nutfall of coconuts in East Africa.

Adults were kept in cages with sides of thick white drill and wire-gauze, in an outdoor insectary at Matuga, near Mombasa, Kenya, and were provided with freshly collected fallen nutlets from which the bracts had been removed. Eggs were normally laid on the walls of the cage. The nutlets were replaced every two days, and all newly hatched nymphs removed and placed in other cages supplied with fresh nutlets every second day. There was some mortality in the first- and second-instar nymphs due to the handling entailed when nutlets were replaced, but in the later nymphal stages it was very low. Under these rearing conditions, the life-cycle from egg to adult was completed in from 35 to 40 days.

The toxicities to Pseudotheraptus of dieldrin, DDT, γ BHC, malathion and pyrethrins in a solvent were compared by topical application of measured-drop doses from an Agla micrometer syringe in a range of five concentrations (except for DDT, where eight concentrations were used). The mortality counts at 72 hr. were taken as the measure of toxicity.

Analysis of the log dosage/probit regression lines indicated that dieldrin was markedly more toxic than DDT to Pseudotheraptus, and that the toxicity to this insect of pyrethrins was of a very low order.

In a supplementary experiment to determine whether the addition of resin improved the toxicity of DDT when applied topically, batches of adults were treated with measured drops of a solution of p, p'DDT (0·5 per cent, for females, 0·25 per cent, for males) and others with the same concentrations of DDT to which coumarone indene resin at one-tenth of the DDT content had been added. The toxicity of the DDT was not enhanced.

It has previously been shown that the sexual maturation of males of Scliistocerca grcgaria (Forsk.) is accelerated by crowding with other individuals of similar or greater age, and that the maturation of males kept in single pairs with older mature males is accelerated as compared with that of isolated males or males kept in single pairs with other young males or females of their own age. The effects of these groupings on the levels of feeding and excretion are investigated in the present work.

Crowded males ate and excreted more than isolated ones during the first ten days of adult life. Five males in a 9-litre cage are sufficient to induce almost the full effect of crowding, and marked effects are shown when only two males are present in such a cage.

After the second or third week, the level of feeding declines. This occurs earlier in early-maturing individuals, so that for a short period the crowded males eat little more or even less than the isolated ones. When the isolated males in their turn become mature their feeding again falls slightly below that of the crowded ones. When all males are isolated, there is a significant tendency for those males which eat least from the beginning of adult life and which increase their weight least to become mature earliest.

The proportion of the food utilised was not affected by density. It was higher during the early period of maximum consumption than it was after the level of feeding declined.

Early in 1959, observations on the farm Tayside, in the East London district of South Africa, suggested that populations of the ‘two-host’ red tick, Rhipicephalns evertsi Neum., were more difficult to control with toxaphene preparations than they had been in the past. Resistance to toxaphene was suspected, and both field and laboratory experiments were carried out to investigate this possibility. Field trials indicated an increase in tolerance by Tayside populations of the tick to toxaphene, γ BHC and dieldrin, but showed no increased tolerance to sodium arsenite or DDT. Similar results were obtained in laboratory experiments where Tayside adults were compared with those of other populations of the tick known to be sensitive to insecticides. Laboratory experiments with larvae indicated a high degree of resistance to toxaphene and γ BHC in the Tayside population, but no increased tolerance to sodium arsenite, Delnav, Sevin or DDT could be detected. This pattern of cross-resistance is similar to that occurring in resistant populations of Boophilus dccoloratus(Koch).

Nupserha bicolor postbrunnea Dutt has become established on olitorius jute (Corchorus olitorius), possibly from its wild food-plant, Sesbania aegyptiaca, and from jute it has spread to other agricultural crops. Incidence on the green-manure crop, Sesbania bispinosa, has increased so much in recent years that it has surpassed that on olitorius jute. The stem diameter most favourable for girdling and oviposition in S. bispinosa ranges from 3·1 to 5 mm., whilst in C. olitorius it is from 2·6 to 3 mm. In spite of this wide difference in preferred stem diameter, the ratio of mandibular length to depth of extra-medullary tissue of such stems in the two plants agrees well.

All the varieties of capsularis jute (C.capsularis) are unacceptable to the adults though they are acceptable to the larvae. Adults obtained from larvae reared on varieties of capsularis jute also show aversion to capsularis types. The pest selects the susceptible olitorius from amongst capsularis jute when these are grown as a mixed crop. Amongst the olitorius varieties, C.G. is the most susceptible. Plants coming within the height range of 100 to 200 cm. are attacked more than others. Girdling causes suspension of unidirectional vertical growth, and this is followed by the appearance of a number of side branches, which are of little value from the point of view of fibre.

In an attempt at some assessment of the errors to which fly-round data obtained for the study of populations of Glossina are subject, three fly-rounds at Shinyanga, Tanganyika, were worked every weekday for four weeks. The species studied was G. swynnertoni Aust. One of the rounds was a ‘transect fly-round ’, the others, the older type, divided into a few long sections according to the vegetation. The catches showed no obvious trend during the experiment, suggesting that the true population had not altered in the period, but in all three rounds there were considerable day-to-day variations in catch and, in this respect, the transect fly-round did not differ from the older method. An analysis of variance of the transect fly-round data showed that the variance between days was greater than could be accounted for by random errors

By considering separately the data collected on certain days of the week, it is concluded that a 7,500-yd. fly-round done once a week could not detect less than a five-fold change in the mean catch. To detect a two-fold change, a 15,000-yd. fly-round done twice a week would be necessary.

The relation between fly-round catch and true density is discussed. This relation is usually termed ‘ availability ’. Earlier workers have shown that its mean value, over periods of about one month, is not necessarily constant; the present work shows that it varies in one place from day to day.

In 1956 and 1957, tests were made in the Sudan Eepublic of four methods of applying insecticides for the control of heavy infestations of midges, particularly Tanytarsus lewisi Freeman, which breed in the Blue Nile. During the winter season the adults occur in myriads in areas adjacent to the river in Khartoum and similar localities, resting in trees and shrubs by day and being attracted to artificial lights after dusk

An emulsion containing 0·4 per cent. DDT applied from the ground to shadetrees in Khartoum at the rate of 0·5·1·0 lb. DDT per tree achieved local control of the midges for three days and detectable reduction for 10 days. An emulsion containing 12·5 per cent. DDT applied from an aircraft to the wooded riverfrontage at Khartoum at 2·1 lb. per acre reduced the numbers of adult midges for the next 15 days, but subsequent applications under conditions of greater air turbulence were ineffective.

The application of DDT as a larvicide in oil solution from aircraft to the river 10 miles above Khartoum, at a concentration approximately equivalent to 0·1 p.p.m. in 2 hours' riverflow, did not appear to reduce the numbers of adults or immature stages at Khartoum, and was followed by some mortality of fish.

Emergence and life-span of wheat bulb fly, Leptohylemyia coarctata (Fall.), have been studied by the use of a field-cage-marking technique. Emergence was investigated by observing the numbers of flies emerging daily from an area of infested wheat enclosed by a cage of fine mosquito-netting, and life-span by making a daily census of marked and individually recognisable flies which had been liberated in the cage. Flies were handled only when being marked and in the later part of the work all observations were made without touching either them or the wheat.

Flies were chilled to render them comatose for marking and under certain circumstances this and the marking was-harmful. Attempts were made to reduce these harmful effects.

Emergence dates varied from year to year depending on the temperatures of spring and early summer, and there were also considerable differences between the emergence dates of populations of adjacent fields in the same year. Consistently, males appeared before females.

The ratio of the number of flies seen to the number known to be alive on each day varied according to weather, flies being more difficult to find on windy days than on calm ones and on bright days than on dull ones.

The observed life-spans of both sexes varied greatly, up to a maximum of 75 days for females and 55 days for males. An exact statement of mean life-span was not possible because there was a tendency for flies emerging later in the season to be less long-lived than those emerging earlier. Most flies of both sexes lived for over 30 days.

The observed life-spans fall short of the true life-spans by amounts that depend on the proportions of living flies seen each day. Two methods are shown by which the mean unrecorded life-span can be calculated.