Catches of Culicoides spp. in a Surrey copse in 1967–69 showed the univoltine C. impunctatus Goetgh. to be dominant. This species reached peak numbers from late May to early June, when nulliparous females were commonly seen at rest on tree trunks. Proterandry was marked in catches from light-traps but not apparent in those from emergence traps or taken at rest. Biting was most frequent 1–2 h before sunset; many bites did not result in a blood-meal. Females taken at rest and from emergence traps could complete their ovarian cycle without a blood-meal, most eggs being matured by the former; midges taken biting matured the fewest eggs but could not do so without a blood-meal. Large full fat-bodies were an indication of nulliparity. It was concluded that C. impunctatus can develop the first egg-batch autogenously, and that the resting habits and responses of females to light and human bait change subsequent to the laying of the first batch of eggs.

The crops and guts of adults of Leptohylemyia coarctata (Fall.) from different parts of England and Scotland contained spores of Septomyxa affinis. This fungus is widespread on dead wheat leaves and grass in wheat fields and is an important food for the flies, especially in south and east England during July and August. Of all flies dissected in 1967, 1968 and 1969, 57%, 39% and 45%, respectively, contained Septomyxa spores. Spores of other fungi, pollen grains, bacteria and yeasts were also ingested. All solid food was ingested in water or honeydew. The weight of the newly emerged female fly almost doubled with the ripening of the first batch of eggs, whereas males remained the same weight or became lighter. Different individuals had different numbers of ovarioles, so the number of eggs ripe and ready to lay at the same time also differed between individuals. The mean numbers, 25·6 ± 0·8 in 1968 and 28·6 ± 0·4 in 1969 were fewer than the usually accepted 32. During August, before all the eggs had been laid, many flies were killed by Entomophthora muscae and Strongwellsea castrans.

Previous work on Phlebotomines has shown that most parous flies in many species may be recognised by the dark residual secretion in the accessory glands; parity can be confirmed by inspection of ovarioles. In the present study 12 species of Lutzomyia were caught in forests near Belém, Brazil, mainly with rodent-baited oil-traps. Many females of the predominant species, L. flaviscutellata (Mangabeira), were parasitised by the protozoan Monocystis. Parous rates based on examination of ovaries were subject to an error of about 5% due to diminution or disappearance of follicular relics. Two successive dilatations of the tunica were seen in L. davisi (Root), suggesting that it had laid two batches of eggs. Biting rates by parous flies varied little during the night, and were somewhat less than those of nullipars. In eight species the dark-gland rate approximated to the parous rate as shown by the ovaries; a small error may have been due to discharge of all secretion, disappearance of follicular relics and premature activity of glands. In contrast to this concordant pattern, four species showed discordance, possibly due to autogeny. It seems advisable to omit oil-trapped blood-fed flies when estimating parous rates by examining glands. Monocystis may increase the dark-gland rate, but it is non-pathogenic or has little effect on life span, and does not hinder blood-sucking.

An experiment was carried out in 1968 in the Lossitete Forest area of northern Tanzania to compare the fly-round and the Langridge-trap as sampling techniques for assessing the effectiveness of 0·4% pyrethrum applications on Glossina pallidipes Aust. when applied from the air. From fly-rounds, population reductions of 64%, 36% and 29% after the first, second and third applications, respectively, were estimated, whereas from Langridge traps the reductions were 11%, 7% and nil, respectively. Taking into consideration the efficiency of the Langridge-trap and the limitations of the fly-round in sampling G. pallidipes populations, it is concluded that the fly-round may give a false assessment of reduction of G. pallidipes after insecticide application.

Field experiments were conducted in the Gambia to measure the convergence of mosquitoes towards single bait-animals (calf or man) or to an equivalent source of carbon dioxide, the mosquitoes being caught in ramp-traps. Catches of unfed females of Anopheles melas Theo. fell off steeply with increasing distance up to 15 yd from animal bait; with carbon dioxide as bait, raised catches were only recorded out to 10 yd. Catches of other Anopheles spp. with calf-bait gave similar results to those for A. melas. A positive effect of the calf on densities at 15 yd was obtained for Culex tritaeniorhynchus Giles but this was less clear-cut in the case of C. thalassius Theo.; with carbon dioxide as bait, raised catches of both species were recorded at 10 yd but not at 15 yd. Both types of bait gave raised catches of the C. decens group only at 5 yd. It is concluded that A. melas and other Anopheles spp. were detecting and responding to the single animal bait from 15–20 yd, C. tritaeniorhynchus and C. thalassius from 10–20 yd, and the C. decens group from 5 yd. In all except the last named group, as also for the other Anopheles spp., on which data are lacking, the range of attraction of carbon dioxide was less than 15 yd. Olfactory cues were therefore held to be responsible for long-range orientation in these three species of mosquitoes, the effect being most marked with A. melas.

Descriptions are given of five new species of Azotus Howard from the Ethiopian region, including one from Mauritius. These bring the total number of Azotus species known from this region to eight. Two described species, A. capensis Howard and A. elegantulus Silvestri, are annotated and figured, and a key to the species is given. The related genus, Ablerus Howard, is recorded from Africa for the first time on the basis of a new species from the eastern Cape Province, and a new East African species of Physcus Howard, is described. A second East African species of the latter genus, one with flightless females, is characterised but not named to species.

The species-patterns and incidence level of ticks on the larger wild animals and on rodents were examined between 1966 and 1969 in the Southern Province, Zambia. The rodents, except for the elephant shrew, porcupine, and hare, were infrequently infested. The antelopes, except for the eland, had a mean infestation of under nine per individual, the buffalo, zebra, suids and the eland over 20. Twenty species of ticks were found on these hosts. On the ruminants Hyalomma rufipes Koch was absent, and H. truncatum Koch was the most frequent; Rhipicephalus simus Koch, R. tricuspis Dön. and R. pravus group were common. Boophilus decoloratus (Koch) was rare, R. evertsi Neum. infrequent except on zebra and lechwe, and R. appendiculatus Neum occurred on only four of the 15 ruminant species examined. Except on the elephant, Amblyomma was represented solely by A. pomposum Dön.

Periodic deticking of cattle, sheep and goats yielded precise quantitative information on the seasonal changes in incidence and species-patterns of ticks. Eighteen species were found on the domestic herbivores. On cattle B. decoloratus was usually numerous and often dominant, except where controlled by dipping or spraying. Compared with infestations on wild animals, H. rufipes was frequent, A. pomposum was replaced by A. variegatum (F.), and R. evertsi and R. appendiculatus were numerous; R. simus, R. tricuspis and the R. pravus group were usually in relatively low numbers.

The proportions of the different species on cattle varied widely between the stations and at different seasons. Intensive stocking, with resultant grazing down of the fieldlayer, increased the R. evertsi numbers markedly throughout the year, and depressed the numbers of Hyalomma sp., A. variegatum and of the less common Rhipicephalids during the dry season; except for A. variegatum, their numbers and those of R. appendiculatus rose, however, during the wet season to higher levels than on the less intensively stocked paddocks. Some evidence is presented that Barotse cattle are more heavily infested than Sindhi and Boran cattle.

The effect of water currents on the dispersion of the larvae of Aedes aegypti (L.) and Anopheles stephensi List, were examined in the laboratory. The larvae represent two distinct respiratory positions, and on the basis of their amount of movement were termed active and inactive, respectively. While active larvae resist water currents, and tend to disperse evenly in a field system, inactive larvae tend to be washed away but also to accumulate in loci of minimal water movement. These findings could be applied to detection of larval populations, control by irrigation and spot chemical treatments in rice fields.

The distribution, habitat and cultivated and wild host-plants of the four species of Oxycarenus found in Ghana are given. O. hyalinipennis (Costa), primarily a savanna species, attacks the seeds of okra, kenaf and cotton; the other species are unlikely to attain pest status. A key to the species is given.

In experiments covering many successive generations of Musca domestica L. (strains NS and WHO/SRS/MHSCO domestica/1), sublethal doses of p,p'DDT applied topically to adults or fed to larvae or adults had no effect on the numbers of abnormal follicles, but the numbers of normal follicles increased in F1–3 when larvae were fed with diet containing 10 parts per million of DDT. These results conflict with those of previous workers. Other possible causes of abnormal oogenesis were examined. Sublethal doses of o,p'DDT and DDE (an impurity and metabolite, respectively of p,p'DDT) had no effect, whereas inbreeding and high-density rearing caused the numbers of normal follicles to fall; the latter caused the numbers of abnormal follicles to increase. There were also heritable differences in oogenesis among three strains of house-fly.

A technique is described in which twelve symbols or fewer can be chosen to code insects with individual marks suitable for mark-recapture studies. The method has been tested on Acrididae and has the advantages that (i) the code is self-checking against loss of marks, (ii) the application is practical, as only one colour is applied to a given individual, (iii) the versatility of the coding permits thousands of individuals to be distinguished, and (iv) an individual can be identified in the field from distances up to three metres without disturbance or rehandling. Guitar oil paints gave the most persistent marks, and were applied with a fine tubular-nib pen.

An account is given of glasshouse experiments in Jamaica to determine the effects of agronomic practice on the fecundity of the sugar-cane pest Saccharosydne saccharivora (Westw.). Eggs (up to one egg per ovariole per day) develop throughout adult life. On young vigorous plant cane the pre-oviposition period was 5·3 days; egg production was highest during the first six days of the oviposition period and declined markedly after 12 days. Mean daily egg production per female over 12 days was taken as an index of fecundity.

The effects of fertiliser application (ammonium sulphate and potassium chloride), wet and dry water regimes, variety (B41227, B42231 and B4362) and crop cycle (plant and ratoon cane), all at different stages of crop development, were observed in four series of experiments involving 1 000 female S. saccharivora. Potassium (K2O) and phosphorus (P2O5) per cent lamina dry matter varied comparatively little, but nitrogen content declined with the age of the plant, increased with application of ammonium sulphate, and was unaffected by crop cycle or variety. Egg production was highest on young cane (up to a mean of 12·0 eggs per female per day), but declined on older cane; it increased with the application of ammonium sulphate but was unaffected by potassium chloride. A direct linear correlation between egg production and the nitrogen content of the leaf (r2 = 0·69, 0·81, 0·52 and 0·69 in series I–IV, respectively) suggested a causal relationship. The pre-oviposition period lengthened and the proportion of females failing to lay any eggs increased in the absence of fertiliser and with increasing plant age. Variation in leaf nitrogen under field conditions could affect egg production.

Three species of Pediobius Walker associated with the oil palm Hispid beetle are studied. One is identified as P. coffeicola (Ferrière), comb.n. The other two are described as new, and a key separating one of them from P. nigripes (Waterston), comb.n., and P. amaurocoelus (Waterston), comb.n., is given. Two new species of Achrysocharis Girault are described, one a parasite of Dipterous leaf-miners in coffee, one reared from galls on mango.

A successful colony of Glossina morsitans orientalis Vanderplank was initiated at Langford in early 1967 with 94 females imported as pupae from Rhodesia. In September 1969, further pupae were received from Rhodesia. Experiments were undertaken in which the four possible combinations of crosses were made between males and females from the Langford colony and from the 1969 importation from Rhodesia. Females of Langford origin performed equally well irrespective of the origin of their mates and it is concluded that there is no evidence that the Langford colony of G. morsitans is either performing abnormally well, because of adaptation to the laboratory, or abnormally badly, because of adverse effects of inbreeding. The poorer performance of females of Rhodesian origin was manifested in poorer survival rather than a lower fecundity; it is attributed to adverse effects on these flies caused by handling of the pupae in the field and/or the stress of the journey from Rhodesia to Langford. It would seem that to avoid any risk of inbreeding in laboratory colonies, wild males only should be introduced periodically.

Populations of Culex pipiens fatigans Wied. were exposed to infection by Plistophora culicis (Weiser) by allowing eggs to hatch in water containing a known concentration of spores. At 26°C–28°C (mean 27°C) exposure of newly hatched larvae to a concentration of 6 000 spores/ml resulted in a 12–9% reduction in the net reproduction rate, and exposure to a concentration of 12 000 spores/ml to a reduction of 24·0%. These reductions were due to an increase in the rate of female mortality and an increase in the number of eggs laid which were non-embryonated and hence did not hatch. At 33°C–35°C (mean 34°C), although the spores of the microsporidian were not killed, development of P. culicis in the mosquito was inhibited. At 19·5°C–20·5°C (mean 20°C), the net reproduction rate of a population exposed as newly hatched larvae to a concentration of 1 890 spores/ml was reduced by 35·6%, due to a greatly increased rate of female mortality. P. culicis, with the inocula tested, is not considered of practical use against C.p. fatigans; more infective spore inocula are not feasible with the present methods of propagating the parasite.