The red spider, Oligonychus coffeae (Niet.), persists in all stages of its development on a few old leaves and ‘ janams ’ (small leaves at the base of the shoot) of tea bushes during the cold weather, and this persisting population is primarily responsible for the attack in the spring.

In pruning, a great many of the old leaves (including janams) are removed from bushes, and, concomitantly, the red spider. Pruned tea is, therefore, less attacked than unpruned tea or ‘ skiffed ’ tea (where just a little is cut off the tops of the shoots) in which comparatively more leaves are left on bushes.

The coconut scale, Aspidiotus destructor Sign., was recorded for the first time from the island of Principe in November 1954, but it is practically certain that it was actually introduced accidentally in 1952.

Prior to 1954, normal fluctuations had occurred in the total annual production of copra of the island, probably correlated mainly with rainfall conditions. However, in 1954 there was a steady and very serious decline in production due to damage caused by Aspidiotus. Several species of endemic natural enemies were found attacking the scale, but the control exerted by them was quite inadequate to prevent astronomical increase of Aspidiotus.

A light-weight spear has been developed to take samples of unlimited size from bulks of cereal grains. The spear is screwed on to lengths of narrow metal pipe, which are used to insert it into a bulk of grain. The sample is sucked out of the bulk through the pipe by the air stream of a domestic vacuum cleaner. This method largely overcomes the disadvantages inherent in other types of spear. The spear can be inserted into a bulk in any direction, even upwards. When sampling downwards, samples can be obtained from as deep as 9 m. Samples can be taken from directly against the walls of a store and as close as 1 cm. to the floor.

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 course of recent investigations of the association of ant colonies with subterranean aphids, it became necessary to develop a suitable method of culturing the latter in order to facilitate experimental work.

Sweet corn (Zea mays) is frequently attacked by Oscinella frit (L.) in southern England because the optimal sowing date (1st–20th May) determines the appearance of the seedlings at the peak of the spring flight (13th–30th May).

A Latin-square experiment including three Thimet treatments and controls showed that almost complete protection could be given by seed-furrow and surface placements along the rows of an 8 per cent, granular formulation at the rate of 2 lb. actual Thimet per acre.

The crop on the untreated control plots was more than halved by the naturally occurring infestation of 45 per cent, of the primary shoots.

Estimation of Thimet residues in cobs taken from the seed-furrow treatment showed that only a very minute trace of toxic material was present.

Tasting tests on cobs from treated plots revealed no detectable taint.

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 following species taken in London on imported bananas has been submitted recently for identification and has proved to be a new species of Dysmicoccus Ferris.

On checking some unidentified material in the British Museum (Natural History), the same species has come to light on imported bananas collected in London earlier. As some of these were labelled “from Canary bananas”, a check was made of all the material in the British Museum (N. H.) of mealybugs from the Canary Islands and it is evident that the species is widespread there but has been misidentified as Pseudococcus comstocki (Kuw.). Furthermore, it has been misidentified as this species on other occasions on imported bananas in England and Egypt and although some of the preparations concerned are labelled as from Canary bananas, it is not possible to determine whether all have come from this source.

In the course of an experiment in malaria control in an inland region of Kenya and Tanganyika, by the use of house spraying with dieldrin, routine catches were maintained of mosquitos resting in artificial outdoor shelters. During the 18 months of the pre-spraying period, catches in the South Pare district of Tanganyika mainly consisted of the principal vectors, Anopheles gambiae Giles and A. funestus Giles, together with small numbers of A. rivulorum Leeson.

During the three years following the spraying, A. funestus disappeared almost completely from the catches, while A. rivulorum showed an increase of about seven times above its former level.

Parts of a district situated in the tropical rain-forest of the Belgian Congo in which onchocerciasis was generally endemic, were investigated to identify the vector and to ascertain its phoretic host, breeding places, habits, etc.

The vector found biting human bait (usually less than 1 metre from the ground) was Simulium neavei Eoub. Dissection of adult females revealed developmental forms of Onchocerca volvulus.

Larvae and pupae were found on crabs of the genus Potamon in fast-flowing stretches of the numerous small streams flowing into the Eiver Congo. The infested streams in the main focus of onchocerciasis were treated by DDT emulsion at a concentration of one part per 500,000 for 30 minutes, every ten days for ten applications.

The good results observed initially were partly offset by the reappearance six months later of small numbers of Simuliids apparently developing from eggs laid by females entering the disinfested area from without.

Glossina medicorum Aust. was collected in considerable numbers in thicket near to Accra, Ghana. The habitat was unusual in that the thicket rarely exceeded 15 ft. in height and big trees were entirely absent. Grassy open spaces within the thicket provided the feeding grounds and a list of possible hosts is given.

There was some suggestion of an association between the abundance of flies and the rainfall in 1958 but noti in 1959, while the size of the flies was inversely correlated with the saturation deficit.

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.

A stretch of river with its flood plain, a habitat of Glossina morsitans submorsitans Newst. and G. tachinoides Westw. in the Sudan savannah zone of Northern Nigeria, which is an important cattle-raising area, is described.

An effective technique for the eradication of both species of tsetse has been developed, using a single application of a 5 per cent, aqueous suspension of DDT by knapsack sprayer in the places of dry-season concentration of the fly, and on the principal midday resting sites, viz., between ground-level and a height of 5 ft. on tree trunks greater than 6 in. in diameter.

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.

Large-scale operational trials of dieldrin lattices applied by aircraft for controlling hoppers of the red locust, Nomadacris septemfasciata (Serv.), were carried out in the North Eukwa outbreak area in south-western Tanganyika during 1958 and 1959. Single swaths of dieldrin aqueous emulsion spray were applied by aircraft to vegetation at wide intervals and in two directions at 90°, forming a rectilinear lattice distribution of poisoned strips of vegetation over large, hopper-infested areas. Hoppers, especially those in bands, were killed on eating the poisoned vegetation in the strips which they encountered during their migrations. An accurate method of lattice layout by aircraft pilots without assistance from ground marking parties was developed, and the whole operation was used on a large scale for controlling the hopper infestation in North Eukwa in 1959.

Cross-mating experiments are reported between adults of the typical, darkclubbed form of Syntomosphyrum glossinae Wtstn., obtained from pupae of Glossina pallidipes Aust. from Kenya and of G. palpalis (R.-D.) and G. morsitans submorsitans Newst. from Northern Nigeria, and the ‘white-clubbed’ form of Syntomosphyrum, originally reported by Waterston from Nyasaland, obtained from pupae of G. morsitans Westw. from Tanganyika.

Fertilised eggs, giving rise to offspring of both sexes, were produced only by crosses between the strains of typical S. glossinae. Crosses in either direction between the ‘white-clubbed’ form and typical S. glossinae resulted in all-male progeny, presumed to develop from unfertilised eggs. It is considered that this is evidence of a physiological barrier to reproduction between the two forms. The ‘white-clubbed’ form is therefore regarded as a distinct species.

The object of this paper is to give taxonomic consideration and status to the ‘white-clubbed’ parasite of tsetse flies that was studied by Dr. D. S. Saunders in the foregoing paper. Since the biological evidence in conjunction with the distribution suggests that it is specifically distinct from Syntomosphyrum glossinae Waterston it is described as a new species, although the morphological separation is weak.

An account is given of work carried out during the third year to eradicate Glossina morsitans submorsitans Newst. and G. tachinoides Westw. from an elongated fly-belt situated in the Sudan savannah vegetational zone of Northern Nigeria, which is an important cattle-raising area.

The total area of the fly-belt, which is isolated as far as G. morsitans is concerned, measures about 120 miles in length and extends, in places, up to almost 10 miles in width. The country involved forms the flood plains and adjacent uplands of the Komadugu Gana river.

Sixty-nine sq. miles were sprayed with DDT during the 1957–58 dry season(between end of January and end of April 1958), and 18 months after completion of work no tsetse has been found in the treated area. These 69 sq. miles formed the dry-season habitat of the fly on this section of the river, and the cost of insecticide and labour involved amounted to approximately £86 per sq. mile. As the zone infested in the wet season greatly exceeded this dry-season concentration area, reclamation costs per sq. mile, when applied to the amount of grazing land made safe for cattle, amounted to much less than the figure quoted.

Successful continuation of this project is ascribed to three salient features of the technique employed: —

(a) A single application only, of a 3·75 per cent, aqueous suspension of DDT from a wettable powder, is sufficient for complete eradication.

(b) A high degree of discriminative or selective spraying is possible: for the elimination of G. morsitans, spraying can be mostly confined to larger tree trunks, in shade, up to a hei ght of about 5 ft.

(c) Artificial or natural barriers to isolate each season's work, and so prevent re-invasion, are not necessary where the fly-belt is of a comparatively narrow and elongated nature. Spraying the re-infested area during the following season is more economical.

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.

In the summer of 1958, experiments were conducted in the vicinity of Brunston Muir, Midlothian, 11 miles SE. of Edinburgh, to measure the flight range of Culicoides impunctatus Goetgh. from its breeding site in the direction of the prevailing south-westerly wind. Thirty-six sticky traps were exposed for six weeks from 27th May to 7th July and captured 23,211 specimens of Culicoides, of which 20,105 were of C. impunctatus (7,207 males and 12,898 females).

Eleven of the traps were arranged in a line over 1,200 yd. The catch of females did not alter for 400 yd., then decreased to a new level which remained constant from 600 to 1,200 yd. This decrease was associated more with the absence of livestock after 550 yd. than with any density/distance regression. The male distribution was similar to that of the females.

Ten more traps stretched over 750 yd. and again no regression was discernible. The female distribution was affected more by the availability of hosts than distance from the breeding site. The male distribution here was different. They appeared to pass less readily through a gap in a narrow belt of woodland than did the females.