In a survey of adult ticks infesting livestock in Ethiopia, 33 species and subspecies were identified. The distribution and abundance of each are discussed in relation to ecology (altitude, climate and vegetation). Amblyomma variegatum (F.) is the most widespread and abundant tick parasitising cattle. A. cohaerens Dön. is common on cattle in wetter western habitats but is replaced by A. gemma Dön. in drier eastern areas. A. lepidum Dön. occupies intermediate habitats. The distribution of Boophilus decoloratus (Koch) is similar to that of A. variegatum. Hyalomma truncatum Koch and H. marginatum rufipes Koch are both common except in extremely arid and humid zones. H. anatolicum anatolicum Koch, H. anatolicum excavatum Koch, H. dromedarii Koch, H. erythraeum Tonelli-Rondelli, and H. impeltatum Schulze & Schlottke are usually associated with camels in semi-arid areas of eastern Ethiopia. Rhipicephalus evertsi evertsi Neum., R. sanguineus (Latr.) group and R. simus Koch do not display marked ecological preferences. East of the Rift Valley in semi-arid areas below 2000 m, R. pulchellus (Gerst.) is abundant on cattle and camels. R. longicoxatus Neum. and R. pravus Dön. inhabit drier localities, but R. lunulatus Neum. occurs only in wetter western areas. Species taken infrequently were A. nuttalli Dön., A. sparsum Neum., B. annulatus (Say), Haemaphysalis aciculifer Warb., H. leachii (Aud.), H. parmata Neum., H. spinulosa Neum., Hyalomma marginatum marginatum Koch, H. marginatum turanicum Pom., H. punt Hoogst., Kaiser & Pedersen, Ornithodoros savignyi (Aud.), R. longus Neum., R. muhsamae Morel & Vassiliades, and R. senegalensis Koch. The seasonal dynamics of the common species and observations on their relationships to tick-borne diseases of man and domestic animals are discussed.

The preference of Culex quinquefasciatus Say for oviposition in rearing water (in which larvae and pupae of the same species had been reared), pond water, tap water (from a well) deionised water and food water (in which larval food was mixed) was tested in a 5 × 5 Latin square. Most oviposition occurred in rearing water, followed in decreasing order by pond water, tap water, deionised water and food water, the differences being significant except between pond water and tap water. Diel oviposition activity of females from wild-caught pupae was studied under tropical normal (light-day) photoperiod (LD 12:12), reversed (dark-day) photoperiod (DL 12:12) and continuous light (LL) for at least three consecutive days at average conditions of 29·3°C and 91% RH. Under conditions of alternate light and dark periods (normal as well as reversed), there was a circadian rhythm, which was unimodal, confined to the scotophase and concentrated in the first half of the scotophase. Under continuous light, activity was greatly depressed, with disturbances both in circadian rhythm and unimodality. It is concluded that the circadian rhythm of oviposition activity of C. quinquefasciatus is predominantly exogenous in nature and regulated mainly by photoperiod, activity being stimulated by darkness and inhibited by light.

Flies of the genus Atherigona spend their immature stages in decaying organic matter (species of the subgenus Acritochaeta) or in the young shoots of various Gramineae (species of the subgenus Atherigona). Descriptions are given of two and 12 new species in these two subgenera, respectively. Most of these species are from India, and are of actual or potential economic importance.

Potato plots in southern England were covered by polyethylene sheeting perforated by 9-mm slits that opened to permit expansion as the plants grew. The slits admitted rain and also some aphids. Covered plants received 93% less immigrant aphids than exposed plants. The greatest protection was from Myzus persicae (Sulz.) (99%), whilst noncolonising species were reduced by 77%. It is improbable that the barrier to movement presented by the polyethylene would differentiate between incoming species or that M. persicae, for which potato is a preferred host, would escape more readily once inside the cover. This suggests that the behavioural barrier to alighting is in response to the reflection of high wavelength light at the polyethylene surface which affected M. persicae more than other species. The method has potential in protection of crops from aphids.

Water-based ultra-low volume (WULV) applications to cotton at fourday intervals of a 1% a.i. polyurea-based microencapsulated formulation of the pheromone inhibitor 9-dodecenyl acetate (E/Z 80:20) in a 0·2-ha field cage in Malawi resulted in an average reduction of 60·2% in nightly mating of females of Diparopsis castanea Hmps. A relatively constant level of inhibitor was maintained by spraying with 30 g/ha initially and decreasing by 10% with each successive spray. Examination of the mated status of 1712 female moths sampled on 88 occasions revealed that, in the presence of inhibitor, mating increased linearly with increasing population density from 22 to 2844 moths/ha (equal numbers of males and females). In an openfield trial, WULV applications of 30 and 60 g of 1 % a.i. microencapsulated inhibitor/ha to isolated cotton plots (0·4–1·2 ha) at seven- and 14-day intervals had no measurable disruptive effect on released populations of moths as measured by oviposition and larval infestation of the crop, although there was some reduction in egg fertility and catches of males in pheromone traps in the treated plots. Timeseries analyses by gasliquid chromatography (GLC) of the residual inhibitor on filterpaper discs and cotton leaves in the field gave similar results, and GLC measurement of inhibitor on filter papers removed at intervals from the test plots showed that inhibitor loss was very rapid, typically 60% within two days and almost 100% after six days. Loss of inhibitor was less rapid in the field cage and under laboratory conditions. Physical and chemical evaluation of microcapsule deposition on cotton plants revealed that spray droplets penetrated to all parts of the plant but that deposition was greatest on the upper laminae of the top leaves of the plant. Methodology for assessing the success of mating-disruption experiments is described and discussed, and the failure of the open-field experiments is attributed mainly to the rapid loss of inhibitor from the formulation in the field.

Sitophilus oryzae (L.) is a pest of stored grain, hut most strains tested so far fail to breed on yellow split-peas (Pisum sativum) and these can be used in admixture to protect other grains from infestation by the weevil. However, seven strains of S. oryzae have been found to breed on yellow split-peas, and the inheritance of this ability was investigated in two of these strains, one from Lesotho and the other from Trinidad. In each strain, the pattern of inheritance showed that the ability to breed on split-peas was controlled by a single autosomal recessive gene. It was not possible to distinguish whether the same genetic locus was involved in each strain. Control is either by two alleles at the same locus or by functionally similar alleles at different loci. There was some evidence that the genetic background of the two strains is different and that the Lesotho strain carries a sex-linked lethal gene. The existence of a heritable ability of some strains of s. oryzae to breed on split-peas suggests that the usefulness of admixture of split-peas with other grain may be limited

The effectiveness of three species of scarabaeids in reducing the survival of Musca vetustissima Wlk. in cattle dung was compared in laboratory experiments in Australia at 27°C in which the arthropod fauna collected in dung-baited traps in different localities at different times of year was added to one-litre dung pads containing known numbers of M. vetustissima eggs. The dung was collected from each site at the time of the experiment. Onitis alexis Klug collected in October and December at Geraldton, and Onthophagus binodis (Thnb.) collected in January at Bunbury, shredded most of the dung, reducing fly survival to 4% of that in control pads. O. binodis collected in March and October at Bunbury, and O. ferox Har. collected in May and December at Busselton, mostly buried dung, reducing fly survival to 32% of that in controls. Factors other than the numbers of beetles were also important in determining the degree of suppression of the fly.

A census of the mealybug vectors of cocoa swollen shoot disease was made weekly on 238 Amazon cocoa trees at the Cocoa Research Institute, Tafo, Ghana, between 1971 and 1976. The six species encountered were ranked in descending order of abundance: Planococcoides njalensis (Laing), Planococcus citri (Risso), Phenacoccus hargreavesi (Laing), Ferrisia virgata (Ckll), Pseudococcus concavocerarii James, P. calceolariae (Mask.). Planococcoides njalensis occurred at a much higher density on infested trees than other species but was found on fewer trees than either Planococcus citri or Phenacoccus hargreavesi. Over 13-week periods the probability of finding a mealybug on a particular tree was 0·87 for Planococcus citri, 0·77 for Phenacoccus hargreavesi, 0·36 for F. virgata, 0·32 for Pseudococcus concavocerarii, 0·23 for Planococcoides njalensis and 0·05 for Pseudococcus calceolariae. The results suggest that the first four species are more mobile than Planococcoides njalensis and could be more important in the spread of disease than has previously been supposed.

An entomological radar was used to observe insect flight activity at a coastal locality in north-western Tasmania during the spring of 1973. Insects were regularly observed to take off at dusk, and local movements from nearby islands were detected on several occasions. Large-scale southward movements of insects across Bass Strait were also observed and were found to be associated with the warm anticyclonic airflows which occur ahead of a cold front. Light-trap catches indicated that the insects were noctuid moths, with Persectania ewingii (Westw.), Heliothis punctiger Wllgr. and Agrotis munda Wlk. dominant. The movements appear to have originated mainly in Victoria and south-eastern South Australia, but it is tentatively suggested that the ultimate source of the moths was in the region stretching westwards from north-western Victoria and south-western New South Wales towards the shores of the Spencer Gulf, South Australia.

Notes are given on the host range, distribution and recognition of the ten species of Scirtothrips recorded as pests: S. aurantii Faure on citrus in South Africa and bananas in Yemen; S. bispinosus (Bagn.) on tea in S. India; S. citri (Moult.) on citrus in California; S. dorsalis Hood on groundnuts in India, tea in Japan and strawberries in Queensland; S. inermis Priesn. on citrus in New Zealand; S. kenyensis Mound on tea in Kenya; S. longipennis (Bagn.) in glasshouses; S. mangiferae Priesn. on mango in Egypt and Israel; S. manihoti (Bondar) on cassava in Brazil; S. oligochaetus (Karny) on cotton in India. S. acaciae Moult, from Ghana is synonymised with S. aurantii Faure, and S. fragariae (Gir.) from Queensland is synonymised with S. dorsalis Hood. Drepanothrips reuteri Uzel, a grapevine pest from Europe and America which is very similar to Scirtothrips species, is newly recorded from Japan on Castanea.

Observations were made on crowded, laboratory-reared. 18–20-day-old males of Schistocerca gregaria (Forsk.) taking off in a wind tunnel. Depending upon the time of day, take-off, which was usually upwind, particularly at higher wind speeds, was related to food availability. Few locusts with full foreguts took off, especially at low air temperatures (20°C), while at high temperatures (35°C), 95% of ones starved for 6 h took off. At 30°C, there was little further increase with starvation for 24–30 h. Females containing large oocytes took off less readily than those with small ones. Take-off was also sometimes initiated by decreases in wind speed and light intensity, and sudden changes in air temperature. A distinct passing shadow stimulated take-off, but not the flickering shadows of other flying locusts. A period of flight immediately beforehand inhibited take-off. The results are discussed in relation to field observations.

The effect of insecticide drift on Glossina morsitans centralis Machado in Botswana was assessed using two-man fly-rounds downwind of the 1700–4000 km2 aerial spraying blocks. The blocks were subjected to sequential applications of endosulfan at between 6 and 12 g/ha with a droplet v.m.d. of 30 μm. Post-spray reinvasion of flies was assessed using two-man fly-round surveys across the edge of one spray block along ideal linear habitat. Each application had an effect on the flies outside the spray block, even at a distance of 20 km downwind. The first two applications of a series had a greater effect than later ones. Total reductions of G. m. centralis after a series of 5 or 6 applications were 92·5% 7 km outside a block sprayed in 1975, 98·3% 6–12 km outside a block sprayed in 1977 and 64·2% 10–20 km outside a block sprayed in 1978. Ageing studies showed that some females 10–20 km downwind of the sprayed area survived up to five applications, and three months after the final application the population there had recovered almost to pre-spray levels. The main front of fly encroachment after spraying across the downwind edge of the 1978 block travelled at about 0·8 km/month in the first 17 months after spraying, but small numbers of flies were found well ahead of the main front. It was concluded that the situation in the drift area could be ideal for the development of insecticide resistance and that adjacent blocks sprayed in consecutive years should overlap by 10 km.

Megaselia sandhui sp. n. is described from specimens of the adult male, female and pupa infesting cultivated mushrooms in India. It is closely related to the other species of Megaselia known to be pests of cultivated mushrooms.

The sterilising effect of 90Sr β-radiation was tested against males and females of Glossina palpalis palpalis (R.-D.) 1–6 days old. The flies were exposed to doses ranging from 2 to 40 krad at a dose-rate of l·09 × 103 rad/min. The optimal sterilising dose for the males was about 7·5 krad. Females that mated with males that had been exposed to this dose failed to produce larvae although the sperm of the treated males was motile. There was no relation between dose and length of life at doses from 2 to 10 krad but at higher doses survival was greatly reduced. Females survived irradiation better than males.

Differences in population growth rates, r, and net reproductive rates, R0, are shown between Glossina palpalis gambiensis Vanderplank, G. palpalis palpalis (R.-D.), G. morsitans morsitans Westw., G. morsitans centralis Machado, G. pallidipes Aust. and G. fuscipes fuscipes Newst. from field-collected data and laboratory colonies. The relationships of these population parameters with temperature are shown as well as the temperature-dependence of T, the cohort generation time. Two rapid methods for estimating r from R0 knowing the mean temperature, and a more accurate rapid method of calculating r direct from the capacity for increase, re, were developed from these data. The stable age-structure, C, calculated from these data was used to show that the laboratory-derived age-specific fecundity, mx, is 22% higher than in the field. The difference is probably due to natural abortion in the field and the better nutritional status of laboratory-reared flies. Deviation from the stable age-structure is shown to be an indication of the sample bias and population equilibrium. The relationships of these parameters to the state of a given population and to optimal timing of control efforts are considered.

The egg production of females of Ixodes ricinus (L.) was found to be closely related to the engorged body weight. The relationship was due almost entirely to the size of the blood-meal. Smaller ticks seemed to be slightly more efficient than larger ones in converting their blood-meal to eggs. Ticks, especially larvae, that overwintered in diapause did not survive as well as those that fed and then moulted in the same year. Larvae that fed and entered diapause early in the autumn did not survive as well as those that fed later in the season. A very high proportion of tick eggs hatched, either in the same year as they were laid or after overwintering. Almost all nymphs and adults became active and climbed to the top of the tubes after moulting. Although most larvae appeared to become active, only about half of them reached the tops of the tubes. This is thought to be a reflection on the fact that larvae are adapted to parasitise small rodents. It is suggested that winter temperatures may play an important part in determining the mortality rate of larvae that overwinter in the engorged state.