Histological examination of the eyes of Glossina morsitans Westw. and G. austeni Newst. showed that visual acuity, as calculated from ommatidial size and interommatidial angle, varies in different zones and planes of the eye, being greatest in the forward-facing region. A study of optomotor responses to revolving black-and-white striped patterns indicated that the eyes could perceive both rapid and very slight movement: responses showed a unimodal distribution with frequency of ommatidial stimulation ranging from one flash/25 s to around 80 flashes/s, with an optimum response at 5 flashes/s. Movement perception was also enhanced by summation of ommatidia simultaneously stimulated, provided the stimulated ommatidia were not contiguous. Strong optomotor response was shown to the movement of black stripes so narrow as to cause merely a 7% reduction in the amount of light entering an ommatidium: from this it was inferred that the eye's contrast sensitivity is well developed. Visual acuity determinations from optomotor responses showed no species or sex differences, and the values corresponded closely with those obtained from anatomical measurements. Of the properties of selected figures examined for attractiveness to orienting flies, linearity of form and brightness contrast with background illumination were deduced to be the most important aspects.

Larval populations of the Anopheles gambiae Giles complex (species A and B) were sampled in Kenya, and from the frequencies of the age distribution of the immature stages time-specific life-tables were constructed. Daily survival rates and instar mortalities showed that there was high mortality amongst fourth-instar larvae, due at least in part to infections of larval nematodes, Coelomomyces and epibionts. Antiserum to the A. gambiae complex was prepared in rabbits so that the precipitin test could be employed to detect the presence of A. gambiae in gut smears taken from possible predators. By this serological technique various spiders, Diptera, Coleoptera and amphibia were identified as predators. These may be very important in regulating populations of A. gambiae even in small collections of water.

The choriothete in Glossina austeni Newst. and G. morsitans Westw. was studied from serial sections of females, from dissected material and whole mounts of eggs and larvae. The choriothete cells are secretory and, while an embryo or first-instar larva is attached to it, are not stretched. The external muscles dilate the uterus or support the uterus and embryo. There is no sign of major folding or muscular tension during dechorionation of the egg. It is concluded, in contrast to recent work, that the choriothete is an organ for the support of developing embryos. Hatching of the first-instar larvae is probably achieved by means of a labral egg tooth.

A new species of Tachinidae of the genus Metacemyia (tribe Acemyini) is described and figured, and keys are given to the Acemyines of the Ethiopian Region. The new species is recorded as a parasite of the wingless Eumastacid grasshopper Manowia sp. nr. alca Bolívar in Malawi. Taxonomic notes are included on the other Acemyini known from the Ethiopian Region.

In Britain adults of the clouded drab moth, Orthosia incerta (Hfn.), appear in the spring and are especially common during April and early May. The larvae feed on various trees and shrubs from May to June or early July, and in orchards may cause damge to the flowers or developing fruitlets. There are six larval instars. These are described, and illustrations are given of the immature stages and adults.

Flight activity of aphids during 1969–71 in a Sitka spruce plantation in north-eastern Scotland was recorded by means of sticky traps. Two flight periods occurred, June–August and September–October. Fewer aphids were caught at 120 and 180 cm than at 60 cm above ground during June–August, while fewer were caught at 60 cm in September–October. After accounting for differences in wind speed at these heights, it was shown that aerial density was consistently higher at 60 cm. The first flight which comprised mostly Elatobium abietinum (Wlk.) was three weeks early in 1971; this was associated with the rapid increase in aphid population on spruce shoots, due to the preceding mild winter. Reinfestation by this species after spraying could follow under similar circumstances. Adelges laricis Vail. and A. viridis (Ratz.) sexuparae were caught in the first flight, and A. cooleyi (Gill.) gallicolae in the second; all galls on Sitka were by gallicolae of A. cooleyi. Aphis fabae Scop, was the most common species in the second flight.

Increased doses of tepa applied by injection to female Diparopsis castanea Hmps. caused a progressive increase in sterility accompanied by a decrease in the number of eggs oviposited from the time of application. After an interval of three days it was shown by histological examination that injected doses of 10 μg of tepa induced degeneration of the developing oocytes and a shrinkage or resorption of some of the mature eggs. After Diparopsis male moths were treated with graduated injected doses of apholate, metepa and tepa and then mated with untreated females, considerable embryonic development without subsequent egg hatch occurred at the lower dosage levels. When tepa-treated Autographa gamma (L.) males at a dose of 10 μg were similarly mated with untreated females histological examination showed that the development of many of the eggs had been arrested at a very early stage; in some instances a greater development, although of an abnormal kind, had taken place.

During studies on yellow fever in Bwamba county, Western Uganda, five non-stop series, each of six 24-h catches, were carried out in an uninhabited area of dense rainforest. All these yielded very large numbers of mosquitoes belonging to the Anopheles gambiae Giles complex. Measures of the central tendency, applied to summed results, show a “typical” pattern with a peak in the second half of the night. Examination of the results in detail reveals great variations in the biting pattern from day to day. These cannot be correlated with local weather conditions and their existence shows that considerable caution must be used in this type of analysis, except in well synchronised biting patterns.

Larothrips dentipes gen. et sp.n., possibly a pollinating agent of yam flowers in Nigeria, is described. The genus Thrips is defined and compared with the closely related monobasic genera Microcephalothrips and Larothrips.

A histological examination of the cuticle of third-instar larvae of Hypoderma bovis (L.) and H. diana Brauer has revealed a large number of mounds with apical pits, which possibly act as chemoreceptors. The pits are in contact with nervous tissue in the epidermis by means of a rod or tube-like structure which passes vertically through the cuticle. Similar structures have been seen in the related genera Oedemagena and Przhevalskiana.

Analyses were carried out at Salisbury, Rhodesia, on the relationship between fat content and residual dry weight in newly emerged adults of Glossina morsitans morsitans Westw., following incubation at constant temperatures between 16 and 32°C for laboratory material, and between 20 and 30°C for field material. The same relationship was investigated for field-collected and laboratory-produced larvae. Sizespecific rates of fat consumption were calculated from these data, and it was shown that the rate of change at temperatures below 20°C was of a different order to that at higher temperatures. Fat reserves in teneral flies reared in the laboratory at 16–32°C were shown to be adequate in flies of 4 mg residual dry weight for survival at rest for at least 24 h after emergence, over the temperature range likely to be encountered in the field. Considerably longer periods of survival were indicated for flies of the same size emerging from field-collected puparia. The latter exhibited a marked seasonal variation in size with the largest puparia occurring at the time of lower temperatures. Smallest puparia occur in the hot-dry season, but even under these adverse conditions fat reserves of most tenerals are adequate for survival for at least 24 h. It was concluded that lack of fat was not likely to cause heavy mortality of stages passed within the puparium over the temperature range 16–32°C. After emergence, survival of smaller flies would depend on their ability to obtain a blood-meal within 24 h.

Cross-mating occurred under laboratory conditions between Diparopsis castanea Hmps. and D. watersi (Roths.), although this subsequently resulted in only a slight egg hatch. Assays involving the use of virgin female traps demonstrated cross-attractancy between the two species. Since abdominal tip extracts of D. watersi females after gas chromatography produced the same pattern of electroantennogram responses as D. castanea female tip extract, it is probable that the sex pheromones of the two species are identical.

Two species, Aethognathus unicolor and A. bicolor, are described as new. The four known species of Aethognathus are parasitic on Stictococcus and Saissetia spp. in Africa. A key to the species and a host-parasite list are provided.

A new tribe allied to the Telsimiini and Sticholotini and a new genus are erected for Ghanius karachiensis sp. n., a Coccinellid predator of Cerococcus hibisci Green in Pakistan.

A survey of Simuliidae in three areas of Pakistan in May and June 1963 yielded 845 pupae, some larvae and 143 captured adults, bringing the number of species for the area from seven to 31. Three species are described as new, and notes are given on other new but unnamed species. A key is given, based mainly on pupae. The previously unknown male, pupa and larva of Simulium indicum Becher are described, together with a new subgenus, Himalayum, for this species. It was breeding on vegetation in a fast river, occurring at 700–1450 m above sea level in spring and autumn, and at higher altitudes in summer. Pupae of S. mediterraneum were found in polluted water. Three species were phoretic, and several were found on or near man or domestic animals.

Laboratory cultures of Cicadulina mbila (Naudé), C. storeyi China and C. parazeae Ghauri derived from field wheat at Salisbury, Rhodesia, during August 1967 were maintained on caged pots of dwarf wheat seedlings. At constant temperatures of 23, 25 and 30°C developmental periods for eggs and adults were similar for all three species. Cultures of C. mbila were reared at a wider range of temperatures (15–30°C) and developmental rates for eggs, and male and female adults were shown to be well expressed by logistic equations. Mean durations are given for the five nymphal stages reared at 26°C. In C. mbila males and females had a similar life span, fecundity was greatest at 28°C, and there was a predominance of males reared from eggs laid by females less than 15 days old.

Distances moved by Cicadulina spp. were investigated at Salisbury, Rhodesia, during 1968–69, by using small plots of oats to trap adults dispersing from populations breeding in Pennisetum clandestinum or Eleusine indica grasses. The shape of the curves constructed for fall of numbers with distance confirmed laboratory findings that populations are composed of long and short distance fliers. The curve for numbers of infective Cicadulina punctures estimated from the gradient of maize streak infection falling from adjoining cereals was also of similar shape. Mean flight times indicated that a steep fall for about 10 m from source is due largely to short distance fliers making trivial movements, and the subsequent gentle fall is due to long distance fliers which may disperse many kilometres depending on the wind speed. There were higher proportions of long distance fliers amongst C. mbila (Naudé) compared to C. storeyi China, and amongst females compared to males dispersing downwind. A predominance of long distance fliers dispersing from drying grasses during April–September, and of short distance fliers present in irrigated grasses and cereals during October–March, causes seasonal differences in the patterns of maize streak infection and in the effectiveness of barriers of clear ground as a preventive measure.

The flight periods of eight species of Adelgids were deduced from suction trap catches in a mixed woodland site at Alice Holt, Hampshire from 1965 to 1970. Nine species from other natural forest areas in the northern hemisphere occurred on trees in the study area, but some immigration may have contributed to the numbers trapped. Large catches (often >200 individuals per day) of three pest species, Adelges laricis Vall., A. cooleyi (Gill.) and Pineus pini (L.), occurred during late May and June. Only small catches (<10 individuals per day) were obtained during July–September. The sexuparae from the non-Picea hosts occurred mainly in May and June whereas the gallicolae from Picea hosts flew during certain periods from June to September. Analysis showed that the threshold temperature for flight was 16°C and that 64% or more of the total monthly catch occurred in the afternoon (13·00–19·00 h). The variation in length of the early summer flight period by ± one week was related to air temperature maxima, but the fluctuation ( ± one week) in the mean date for flight of each species in the early summer period is probably connected with the phenological condition of the host-plant.

The host range and feeding habits of seven species of Culex mosquitoes at Keneba, the Gambia, are described from precipitin tests of blood-meals and from observations on their attraction to calf, man, duck and pigeon baits. Feeding habits were classed nonspecific, mammalian or ornithophilic. Culex thalassius Theo. was non-specific, bloodmeals being identified from mammals (59·5%), birds (38·1%) and reptiles (2·4%). Large numbers were attracted to calf, man, ducks and pigeons. C. tritaeniorhynchus Giles fed almost exclusively on cattle: 17 of 19 blood-meals were identified as from cow. Many specimens were taken at calf, smaller numbers at man, and the few attracted to ducks fed readily. Birds were the main source of blood for C. decens Theo. (54·8%), C. invidiosus Theo. (87·5%), C. nebulosus Theo./cinereus Theo. (93·3%), C. tigripes Grp. & Charm. (98·3%), C. univittatus Theo. (two out of three) and C. weschei Edw. (one out of one). Reptile feeds were recorded for C. decens (14·3%), C. invidiosus (5·0%), C. nebulosus/cinereus (6·7%) and C. univittatus (one out of three). C. invidiosus and C. univittatus were common only at pigeon bait where some 13% fed on the birds.