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.

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 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.

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.

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.

1. A series of exploratory experiments on the relationship between temperature and toxicity of DDT films to adults of Tribolium castaneum, and larvae of Plutella maculipennis, are described. The main conclusions with T. castaneum are:—

(a) When the insects are continuously kept on the film at different temperatures there is a higher kill at higher temperatures.

(b) When the insects are exposed to the film for about 24 hours at the same temperature and then kept away from it at different temperatures there is a higher kill at the lower temperature.

(c) When the insects are kept on the film at different temperatures for about 24 hours and then kept away from the film for reaction at the same temperature, there is a higher kill in those kept on the film at the higher temperature.

(a) and (b) above apply equally to larvae of P. maculipennis but (c) is reversed. The probable cause of this reversal appears to be the observed fact that at higher temperatures these larvae cover the film with much more silk thread and thus avoid contact to a greater extent than at lower temperatures.

2. A review of literature, in the light of the conclusions arrived at, indicate that many of the observations made upon the temperature-toxicity relationship can be accounted for by the following generalisations:—

(a) Insect resistance to poisons changes with temperature as do its other vital activities, increasing up to a critical degree and afterwards declining.

(b) The amount of poison reaching the site of action in unit time also varies with the temperature, generally but not always, increasing with its rise. Insect activity, especially locomotor and respiratory, may play an important part in these effects.

(c) The apparent effects of temperature on insecticidal action is the combination of these two factors, namely, resistance and pick-up.

A quantitative survey of Wheat Bulb Fly (Leptohylemyia coarctata) was made in Yorkshire in 1945, and the distribution of the fly is discussed in relation to general observations and records in the years 1935–1946. The distribution is shown in themap (fig. 2).

One hundred and thirty-six fields on 86 farms were examined and Wheat Bulb Fly was present in over half of the farms and fields; in 8 fields (6 per cent.) it was present in moderately high numbers, and in 2 fields (1·5 per cent.) it was present in numbers sufficiently high to be likely to cause a failure in a bad wheat year. It was estimated that two or three thousand acres of wheat and rye in Yorkshire are likely to have a reduced crop as a result of Wheat Bulb Fly attack in an unfavourable season. Over half the dangerous area is near Selby. The only large area where Wheat Bulb Fly was virtually absent was the Yorkshire wolds.

Experiments were carried out during 1945 and 1946 to determine the effect of insecticides, particularly DDT and BHC, on certain species of Syrphids and Coccinellids. In addition, some preliminary data was obtained on toxicity to parasitic Hymenoptera and a predatory Cecidomyiid species.

In some experiments other insecticides were used for comparative purposes and where possible data were obtained on the effect of the insecticide not only on the predator but also on the host and the host-predator relationship.

A review of the work carried out on mercury as a preservative against stored grain pests is given.

The influence of the duration of exposure to mercury vapour upon eggs of different stages of development is discussed.

Temperature and humidity within ordinary limits do not affect the efficiency of mercury.

Under airtight conditions this preservative is effective within a radius of three feet in receptables with or without grain.

Paper strips coated with mercury cannot be recommended for grain stored in bags and kept in piles because pressure and weight of the grain, or even shaking, will cause the mercury to be expelled from the strips.

Mercury dispersed in chalk cannot be used for grain destined for consumption. It is, however, quite suitable for preserving grain for seed.

Plastering the walls with mercury paste or afflxing slabs to the walls of godowns is not effective owing to the limited range of mercury vapour.

Application of mercury in various types of receptacles is discussed and advocated. Fumigation with mercury does not seem to be practicable.

Galuzo (1941) in his ecological studies of the tick fauna in Kazakh S.S.R. states that the nymph of Hyalomma detritum, Schulze, overwinters on the host, that he is of the opinion that H. savignyi, Gerv., hibernates in the adult stage away from the host (in animal quarters or houses) and that he found hibernating nymphs of H. marginatum, Koch, in grass meadows.

In the course of field work carried out in Palestine during the winter 1945–16 only a few adult male and female ticks (some gorged) were found in the Jordan Valley and the Negeb, and none in the more temperate parts of the country.

This paper deals with Glossina pallidipes, G. austeni and G. brevipalpis as they occur on the Kenya coast.

Temperature and saturation deficiency both exert a generally inverse effect on the activity and apparent density of both G. pallidipes and G. austeni. True density also varies inversely as the s.d.