A scattergram method was developed for explaining the variability in the levels of fat, residual blood-meals and residual dry weights (RDW) of field samples of Glossina. The pattern of changes in mean RDW and fat levels was shown to be similar for five species of Glossina (G. morsitans morsitans Westw., G. swynnertoni Aust., G. fuscipes fuscipes Newst., G. palpoiis palpalis (R.-D.) and G. tachinoides Westw.) but different for the two sexes. On the basis of previous laboratory and field work, a simple descriptive model is developed that suggests priority pathways during the life of the adult fly for the products of successive blood-meals. Initially, for tenerals of both sexes, the priority is to increase thoracic musculature (RDW) without excessive production of fat. Subsequently, male flies devote each blood-meal exclusively to the production of fat, an energy store used mainly for flight activity. Females show a gradual increase in both fat and RDW levels, which probably corresponds with the development of the larva in utero. Wing-fray measurements support this interpretation. During each pregnancy cycle, females accumulate a reserve of fat over and above that necessary for the production of each larva. This is apparently required at the end of each cycle when res piratory losses exceed the energy supply from blood-meals taken. Mean thaematin levels of the four larger species studied (G. morsirans, G. swynnertoni, G. fuscipes and G. palpails) also showed a consistent pattern of change during each pregnancy cycle. Females apparently feed once at the beginning of each cycle, once at a stage of pregnancy when the larva in utero is approaching the moult from the second to the third instar and finally during the middle of the third larval instar, when the meal may be quite small and repeated.

Low fecundity in the laboratory was found in populations of Aedes aegypti (L.) exhibiting Black tergite (Bt), a phenotype characteristic of the feral A. a. formosus (Wlk), whereas high fecundity was found in six domestic populations of A. a. aegyptiin which the phenotype was absent. An investigation of the cause of low oviposition by the feral population indicated that behavioural differences in mating and feeding were not responsible; egg retention was identified as the major factor. Introduction into laboratory procedure of a variable simulating the feral environment, i.e., coconut-shell infusion at the oviposition site, induced a highly significant increase in feral fecundity both through its chemical constituents and visual attraction. Differential response to oviposition site is discussed in relation to the evolution of subspecies of A. aegypti.

A laboratory colony of Aedes fluviatilis (Lutz) was established in ambient conditions in Brazil in which temperature varied from 22 to 31°C and relative humidity from 61 to 73%. Females laid eggs 3–13 days (mean 5·6 days) after a blood-meal and produced, on average, 64·3 eggs per batch. Eggs were usually deposited directly on the surface of water and preferentially on water that had previously contained fourth-instar larvae. The eggs proved to have little resistance to desiccation, hatching rates being reduced when eggs were kept on dry filter paper for only 1–3 days. Hatching took place following the detachment of a cap-like portion of the anterior end or through an irregular longitudinal split along the side of the egg. In different experiments, about 10–20% of eggs failed to hatch. Eggs usually hatched 2 days after oviposition. The average length of larval life was 10·2 days, and the highest proportion of larvae pupated on day 9. The duration of the successive immature stages increased geometrically with age. Mortality was 1–2% in each of the first 3 larval instars but rose to about 10% in the fourth. In the larval stage, males developed more rapidly than females. Crowding lengthened the duration of the larval stage, reduced the numbers surviving to pupate and resulted in a disparate sex ratio with emergent males much more abundant than females. Pupation occurred throughout the day and night with a slight peak at 05.00–06.00 h. The pupal stage lasted 1–3 days, usually 2 days, and was the same in both sexes.

A comparison was made of the efficiencies of catching parties with hand nets and electric back-pack and screen traps for the capture of Glossina palpalis palpalis (R.-D.) and G. tachinoides Westw. in northern Nigeria. Whilst there was little to choose between the various devices during standing catches, one electric back-pack caught up to four times as many G. palpalis as two men with hand nets during moving catches on fly-rounds. Two reasons for the observed variation in success rate of the catching party with hand nets are suggested, and estimates are made of the relative efficiencies of each method at capturing flies during a single traverse of a fly-round. The combined use of the electric back-pack and screen drawn immediately behind the back-pack wearer recorded the arrival height of the flies, whilst hand-net catches tended to reflect the heights at which the flies spent most of their time after arrival. There were differences between the sexes both in arrival height, perhaps related to differences in resting heights on the vegetation, and in the fat and haematin levels of flies caught in hand nets above and below the waist. High ambient temperature reduced the average height of the visits of both sexes to human bait. The relevance of the results obtained in this study to sampling tsets populations is discussed in relation to various seasonal changes in hand-net samples recorded in the literature.

Tomato yellow leaf curl virus (TYLCV), which is transmitted by Bemisia tabaci (Gennadius), is a very destructive disease of tomato i Israel. Soil mulching with yellow polyethylene sheets delayed the spread of the disease for at least 20 days. In laboratory and field experiments, B. tabaci was found to be more attracted to yellow polyethylene than to straw or to aluminum- or blue-coloured polyethylene. A combined treatment of mulching with yellow polyethylene sheets and 1% sprays of azinphos-methyl starting 20 days after germination was the most effective in preventing the spread of TYLCV.

The night resting sites of Glossina tachinoides Westw. were observed in riverine forest at Bara, Bauchi State, northern Nigeria. The flies were marked with an ultraviolet-reflecting paint and released at dusk. They were detected with the aid of an ultraviolet lamp. Most of the flies (84·6%) rested on leaves (68·3% on the upper sides) and on small twigs and creepers (11·5%). The resting heights ranged from ground level up to 6·8 m. The average resting height was highest (2·6 m) in the mid-rains at 20.00–24.00 h; however, at 24.00–04.00 h at the same season the mean height was only 1·6 m. Resting height was lowest (1·3 m) in the early rains. Females were found to rest slightly higher than males and, in moonlit periods, both sexes had a tendency to perch higher. The night resting behaviour of G. tachinoides is compared with that of G. palpalis palpalis (R.-D.), which was investigated in an earlier study at the same location. There is much similarity in the behaviour of the two species, but G. tachinoides selects lower resting sites, and a slightly higher proportion of this species is found to rest on leaves as opposed to small twigs

Published laboratory measurements of the levels of fat and haematin in Glossina following a blood-meal were used to develop a prediction of the relationship between fat and haematin during the course of the feeding cycle. The fat-haematin relationship appears to be nearly linear over the later part of the feeding cycle. Data from three field studies onG. morsitans Westw.,G. swynnertoni Aust. and G. fuscipes Newst. were analysed in the way suggested by the prediction, and the observed rates of fat depletion were used to estimate flight activity of male flies towards the end of each feeding cycle. Results for G. palpalis (R.–D.) and G. tachinoides Westw., obtained in other studies with new electric sampling devices as well as by men with hand nets, illustrated particularly clearly the fat-haematin relationship over the whole of the feeding cycle. This was made possible by the electric traps catching more flies nearer to the start of their feeding cycle than the men with hand nets. A comparison between the different areas suggested that the fat level may trigger the onset of feeding behaviour inGlossina.

Glossina spp. were collected in south-western Ethiopia and were found to have a continuous distribution from the Sobat River Basin to the southern Rift Valley lakes of Chamo and Abaya. Their limits to the north and east of this range was not determined. Along the Omo River, Glossina inhabit a continuous band from 20 km above Lake Rudolf to at least as far as Abelti, 167 km south-west of Addis Ababa. The species collected were G. pallidipes Aust., G. fuscipes Newst., G. morsitans submorsitans Newst. and G. Iongipennis Corti. The ratio and numbers of G. pallidipes and G. fuscipes suggest a relationship between the latter and the number of hippopotamus along the Omo River. Both G. pallidipes and G. Iongipennis were caught biting at night.

All available records showed that Eldana saceharina Wlk. occurs in wild plants in all suitable areas of Africa south of the Sahara. Until a few years ago, it was only of economic importance in West Africa as an occasional pest of maize and sugar-cane, but a crop-feeding form has recently appeared in East Africa. Biological studies were carried out in the field and laboratory at Kawanda, Uganda, between 1970 and 1972 using natural and artificial larval diets. The life-cycle lasted 2–3 months, depending on temperature, and the number of larval instars depended partly on the diet. The adults lived for two weeks, during which time the females each laid 400–600 eggs. The majority of eggs and small larvae were taken by ants, but sufficient larvae survived to cause considerable damage. The pupae and larger larvae lacked efficient natural enemies in East Africa, and the introduction of parasites is suggested to prevent serious crop damage. The relatively evenly spread rainfall at Kawanda allowed maize to be planted every month so that field populations of E. saccharina and the other stem-borers Chilo partellus (Swinh.), Busseola fusca (Fuller) and Sesamia calamistis Hmps. could be studied throughout the year. Collections from maize, sorghum and sugar-cane showed that, although the four species attack the same host-plants, they occupy different ecological niches.

Components of dried citrus pulp were isolated and tested for arrestant activity for Atta cephalores (L.) and Acromyrmex octospinosus (Reich). Both lipid and non-lipid components contributed to the acceptability of the pulp. Arrestant activity was greater in the non-lipid fraction. Sucrose was found to be the most active single component of the non-lipids. The arrestant properties of the pulp were attributable to the particular balance of constituents rather than to any single component. The results are compared with the response of other insects to similar phytochemical stimuli.

Studies in Queensland showed that an outbreak of Austrosimulium pestilens Mack. & Mack. occurs if the water-level in a river rises enough to release eggs buried in the river-bed. Following such a rise, the larval development of A. pestilens was completed in 6–7 days in summer and 9–10 days in winter, and after a pupal period of 1·5–2 days in summer and 3 days in winter, adult eclosion began. Most flies emerging during the first 1–2 days were males, but females were slightly predominant later. A. pestilens emerged throughout the diel; at night there was a drop in the numbers emerging, and this was followed by a distinct early morning peak. Following a rapid rise and fall in river-levels, adult eclosion and mating occurred over a period of several days early in an outbreak, but after high river-levels of long duration, eclosion and mating occurred over a much longer period.

In a study in the Gambia on the relationship between wind direction and the direction of flight of mosquitoes, high-voltage electric grids were used as screens in conjunction with suction traps. Mosquitoes contacting or attempting to fly through the grids were electrocuted. The screening efficiency of the grids was estimated to be 75–80%, and the grids had no demonstrable effect on wind speed. The traps were set up in pairs with their mouths at ground level, one trap in each pair being screened on the upwind and the other on the downwind side. In this way, the mosquitoes could be segregated into those that were flying predominantly upwind and predominantly downwind, respectively. The results indicated that some 64% were flying upwind at this level, but this proportion varied considerably over a period of days, with nightly extremes of 87 and 43%; there was little difference between species. This variation was not correlated with wind speed, but there was some evidence that the presence of moonlight led to a greater degree of upwind flight.

Altering the proportions by weight of first-stage workers in groups of large workers from 26 to 40%, or of fourth-and fifth-stage reproductive nymphs in groups of mixed workers from 0 to 15%, did not affect wood consumption by laboratory cultures of Nasutitermes exitiosus (Hill). However, increasing the proportion of soldiers in groups of mixed workers from 0 to 15% decreased food consumption, which was very closely related to: the weight of workers present. The presence of 7·5% of large workers near to ecdysis had no significant effect, but food consumption was depressed when the proportion reached 15%, apparently due to high mortality among the moulting workers. It is concluded that caste composition can be an important factor in laboratory tests of materials against termite attack and that, unlike soldiers or large workers near to ecdysis, first-stage workers and late-stage reproductive nymphs of N. exitiosus are substantially independent castes, at least in their feeding.

Argas persicus (Oken) fed readily on avian hosts and consumed more blood and produced more eggs than on mammalian hosts. Ornithodoros tholozani (Lab. & Mégn.) fed equally well on chicken and various laboratory animals and converted the blood of all hosts into eggs at equal rates. O. moubata (Murr.) was intermediate, feeding more readily on chicken, rabbit and guineapig than on mouse, rat or hamster, and showing greater utilisation of blood of chicken and rabbit than of the other hosts. The relation of these phenomena to the natural host spectra of the 3 tick species is discussed.

A total of 18 873 mosquitoes comprising 18 species in 4 genera was collected during a series of 12 monthly all-night collections on bovid baits near the village of Sattoki, Punjab Province, Pakistan. Anopheles pulcherrimus Theo. and usually An. Culicifacies Giles and An. Stephensi List. had unimodal biting rhythms. Mansonia uniformis (Theo.), An. Annularis Wulp and An. Nigerrimus Giles had essentially unimodal rhythms, with most feeding occurring early in the evening but with occasional very slight morning increases.Aedes caspius (Pall.), Culex pseudovishnui Colless, C. tritaeniorhynchus Giles and usually An. Subpictus Grassi had distinctly bimodal biting rhythms, with well-defined early evening and predawn peaks. An. culicifacies, An. Stephensi and An. Subpictus occasionally had multimodal rhythms or were arhythmic. Some species exhibited more than one type of biting curve. In species having a distinct bimodal curve, the amplitude of the predawn or dawn increase varied considerably from month to month. The anophelines, especially An. culicifacies, An. Stephensi and An. Subpictus, exhibited a marked seasonal shift in feeding times, with most biting occurring at dusk during the cold period and late at night during the warm period. However, all components of the biting curves for these species were maintained at varying magnitude throughout the year, perhaps suggesting seasonal variations in the relative frequency of more than one behavioural genome. The remaining species exhibited little or no seasonal change in biting rhythms

A series of investigations was conducted to evaluate the comparative attractiveness of cattle, sheep and goats to Glossina morsitans morsitans Westw. and G. pallidipes Aust. in the Zambesi Valley, Rhodesia. It was shown that cattle are subjected to in excess of three times the challenge by male G. m. morsitans than either sheep or goats. Due to the repellent effect of man's presence on the attraction and feeding of female G. m. morsitansand both male and female G. pallidipes on the bait animals, no rational relationship could be postulated for them. Possible factors accounting for the difference of attractiveness between the three bait species are discussed.

The comparative attractiveness to Glossina morsitans morsitans Westw. and G. pallidipes Aust. of donkeys, cattle, sheep and goats in the presence of wild game was examined during two investigations in a middle-veld area of Rhodesia. Host preferences were assessed by the identification of blood-meals collected in the grazing area. Both cattle and donkeys provided a high proportion of the diet. Sheep and particularly goats were fed upon to a minor degree. The significance of the findings is discussed in relation to tsetse control.

Males of Glossina morsitans Westw. and G. pallidipes Aust. labelled with radiocaesium (137Cs) were released in their natural habitat and later recovered on four occasions in the hot, hot wet and cold dry seasons in Rhodesia. The rate of excretion of the radioisotope was related to previous laboratory results to give estimates of activity, temperature regulation and energy utilisation in the field. It is considered that male G. morsitans are unlikely to fly for more than a few minutes per day. The hunger cycle duration is estimated as 3·5–4 days for G. morsitans males and 5·5 days for G. pallidipes males. Temperature regulation within the range 23–27°C was exhibited by both species, especially in the winter.

A trail pheromone, methyl 4-methylpyrrole-2-carboxylate (M4MP2C), of Atta texana (Buckley) was tested in the laboratory as a possible component of attractive poison bait for the leaf-cutting ants A. cephalotes (L.), A. sexdens (L.) and Acromyrmex octospinosus (Reich). For all three species, M4MP2C when impregnated onto paper discs increased pick-up of the discs. It also increased pick-up by Atta sexdens of a citrus-pulp bait. The addition of M4MP2C made them easier to find, although at high concentrations it was repellent. It did not affect the average number of ant investigations before the bait was picked up. The pheromone remained on citrus-pulp bait in active concentrations for approximately four days. To test -the effect of M4MP2C as a foraging stimulant for A. cephalotes, an apparatus was constructed in which the ants passed in single file over a transparent section of the trail where they were counted with a photoelectric cell. When bait impregnated with M4MP2C was placed on the foraging table, large increases in activity were recorded away from the nest but only small increases were recorded in the nest and at the nest entrance. When air containing M4MP2C vapour was injected into the fungus chamber, an increase in activity was recorded at the nest entrance, but this increase was not repeated when known amounts of the pheromone impregnated onto baits of filter-paper discs were added directly to the fungus chamber. It is suggested that factors other than M4MP2C are also involved in the stimulation of foraging activity. The experiments suggest that M4MP2C could play some part in the formulation of an attractive bait for the control of leaf-cutting ants.

A total of 2609 blood-fed females of 23 species of Aedes and Culex was collected, mainly from outdoor resting sites or in unbaited suction traps, at two localities in The Gambia. The host-feeding patterns of the mosquitoes indicated by the results of precipitin tests on the blood-meals were of thiee types: those in which large mammals were the predominant hosts, those where mammals, birds and reptiles were represented and those in which avian feeds predominated. C. tritaeniorhynchus Giles had fed predominantly on cattle, and small numbers of nine species of Aedes had fed on large mammals. C. thalassius Theo. was non-specific in its feeding habits, with feeds from a wide range of mammals and birds and a few reptiles. No evidence was found for a change in the feeding habits of C. thalassius with increasing age. C. poicilipes (Theo.) also fed on mammals and birds. Birds were the primary hosts of C. tigripes Grp. Charm., C. nebulosus Theo./ C. cinereus Theo., C. decens Theo., C. invidiosus Theo. and C. neavei Theo., although the feeds of C. decens included a large proportion on bats.