A new species of the genus Dicraeus was observed in numbers ovipositing on the heads of rain-fed millet in Upper Volta. In Senegal, it was reared in field trials from heads that had been exposed for one week following onset of flowering, the highest infestation being in heads that flowered during the first two weeks in October. In Nigeria, larval feeding lesions and withering were observed in seeds from individual inflorescences containing pupae. The species is described as D. pennisetivora sp. n. from the adults of both sexes, puparium and third-instar larva. A further three African species that are closely related to it are described from adult material alone, and the characters of the adult terminalia of two further closely related but already described species are given. The six species are keyed. There being no previous description of the larva of any species of this genus, the larva is likened to those of other chloropid genera. The generic diagnosis is modified. It is suggested that within this genus the structure of female terminalia determines the structure of male terminalia, in which case subgenera based upon characters of male terminalia are purely artificial.

Five aspects of the behaviour of the Triatominae are reviewed: hostfinding, defence from predators, habitat selection, activity patterns and substrate preferences, and mating and oviposition behaviour. It is emphasised that knowledge of behaviour is largely restricted to the three species Triatoma infestans (Klug), Rhodnius prolixus Stål and Panstrongylus megistus (Burm.) and that the behaviour of other species, particularly those with predominantly sylvatic habits, may be quite different in some respects.

The biology and pest status of the common species of Sitobion, Metopolophium and Rhopalosiphum found on wheat, barley and oat crops in Europe is critically reviewed. After preliminary sections on species and sampling, the factors that induce the production of the different morphs of cereal aphids are considered. Basic life-cycles are described and the importance of migration and dispersal considered. Host-plant preferences, survival and reproduction on different Gramineae, and feeding site preferences are considered, particularly in relation to the type and amount Of damage caused by the aphids. The effects of constant temperatures on the biology of some species have been investigated, but little is known about the effects of weather in the field. There have been few quantitative studies on the effects of natural enemies on cereal aphids, but the evidence suggests that they may be important in reducing their numbers. Side-effects of pesticides and fertilisers on aphids are also discussed. Aphids may reduce grain yield and quality. Direct damage may result from reductions.

Attempts were made to find alternative, less persistent, toxicants to aldrin for use in baits against Anoplolepis longipes (Jerd.) in the Seychelles. More than twenty toxicants were tested (some in more than one formulation) for effectiveness as poisons and for repellency to ants at the concentrations used in baits. None was as effective as aldrin, but certain formulations of pirimiphos-ethyl, pirimiphos-methyl and mecarbam were promising because they gave good kill of ants in the laboratory and were of relatively low repellency and therefore acceptable in bait formulations.

Prostaglandin F (PGF) and E2 (PGE2) were assayed in the reproductive organs, salivary glands and egg-batches of laboratory-bred males and females of Hyalomma anatolicum excavatum Koch. Salivary glands and reproductive organs were dissected from unfed male and female ticks as well as from ticks that had fed for six days on rabbits; these organs were cultured for 24 and 72 h in tissue culture medium-199 with Earle's salt and HEPES buffer at pH 7·6 and 37°C. The amounts of PGF and PGE2 accumulated in the culture were determined by a radioimmunoassay using specific antibodies. Both salivary glands and reproductive organs were shown to synthesise PGEa and PGF. This synthesis and also the prostaglandin content of the organs were significantly increased after engorgement. The synthesising capacity and content of PGE2 and PGF in both the salivary glands and reproductive organs were higher in the female than in the male.

Samples of female Glossina morsitans morsitans Westw. were collected in the Zambesi Valley in Zimbabwe-Rhodesia using an electric net and aged using the overian ageing technique. Similar age-structures were demonstrated in the four seasons studied, and the life-table constructed on the basis of the reproductively active members of the population indicates that females produce more than two female offspring in a lifetime. The tsetse population is considered to be regulated by the survival of the newly emerged teneral flies and non-teneral nullipars. The intrinsic rate of natural increase (rm) is calculated from the life-table as 0·01204 for the reproductively active sector of the population.

The biting habits of Simulium austeni Edwards, a species widely distributed through Europe and European Russia, were investigated in a population of flies creating a medical problem along the Stour Valley, Dorset, England, in May each year. Surveys were made by questionnaires and ‘bite-recording forms’. Sweep-netting, suction-trapping and sticky-trapping of adult flies was carried out. A search was made for oviposition sites. After initial complaints in the early 1960s, the problem reached a peak between 1969 and 1971 and has since shown an apparent decline. Women suffered more than men, with most bites received on the lower limbs. Biting activity was greatest between 09.00 and 21.00 h, and flight activity was greatest in the afternoon. Extensive male swarms were associated with mating and smaller female swarms with blood-sucking. Mating probably precedes biting. The absence of eggs from surface vegetation or stones and their widespread occurrence in the sediment, suggest that oviposition takes places directly into the water.

In Cameroun, about a dozen species of insects were associated with oil palm inflorescences. All except Prosoestus spp. visited female inflorescences after visiting male inflorescences during anthesis and transported pollen to the receptive female flowers. At a rough estimate, about 20 000 individuals visited each female inflorescence during the period of receptivity, and about 70% of the pollen transported was viable. In Peninsular Malaysia, Thrips hawaiiensis (Morg.) is almost certainly the main pollinating agent. Some 200 000 individuals were estimated to visit a single male inflorescence. They also visited female inflorescences, Where up to 7.3 thrips per flower were estimated to be present at any one time, each carrying 4–5 pollen grains, of which 76% were viable. In Peninsular Malaysia and Sabah, a momphid moth. Pyroderces sp., may contribute to oil palm pollination. As natural pollination of all oil palms in Cameroun and taller palms in Peninsular Malaysia is considered adequate while in most areas of Sabah where few insects visit the flowers it is inadequate, it is concluded that the insects observed achieve pollination so the oil palm should be considered an entomophilous rather than an anemophilous plant.

The vertical distribution of flying mosquitoes beside an area of dry-season irrigated rice-fields was investigated at Bansang in the Gambia. Suction traps were set up at seven levels (0·1, 0·25, 0·5, 1·0, 2·1, 3·9 and 7·9 m) over a dry open field. Vertical distribution profiles were of two types. In the first, mosquito density decreased progressively with height and 80% or more of the total were taken below 1 m. Mosquitoes token included Anopheles gambiae Giles s. l., A. pharoensis Theo., Culex antennatus (Becker), C. ethiopicus Edw., C. neavei Theo. and Mansonia spp. Although the largest catches of A. rufipes (Gough) were taken in the lowest traps, this species Showed a tendency to a bimodal vertical distribution profile during. the early part of the night. In the second type, in which mosquitoes were frequent at all heights, C. poicilipes (Theo.) was the sole example. For the more common species at least, flight altitude declined with increasing wind speed. For a few categories of mosquitoes, flight levels decreased as the night progressed, but the presence of moonlight, or its absence, had no demonstrable effect.

A study was undertaken of the seasonal abundance, feeding habits, resting habits and malaria infection rates of the sibling species Anopheles gambiae Giles and A. arabiensis Patton on the Kano Plain, Kenya, and the surrounding foothills. A. arabiensis was the dominant species on the plains and A. gambiae in the foothills. A. gambiae was highly anthropophilic with 92% feeding on man, whereas 59% of A. arabiensis fed on cattle. In both species, the choice of host was affected by the availability of cattle. A. arabiensis rested out of doors more commonly than A. gambiae. The sporozoite rate in A. gambiae was 5·33%, 15·98 times higher than the rate of 0·33% found in A. arabiensis.

Damage by larvae of Characoma stictigrapta Hmps. to cocoa in Ghana was investigated. The noctuid caused serious damage to vegetative parts and pods, and this damage was found to be aggregatory and to fluctuate throughout the year. The abandoned tunnels of the larvae were invaded by other cocoa invertebrates as well as by blackpod fungus, Phytophthora palmivora, a serious cocoa disease, which damages about 19% of the crop annually.

The response of F1 larvae from reciprocal crosses of susceptible × organophosphorus-resistant strains of Lucilia cuprina (Wied.) to diazinon was intermediate in relation to that for larvae from the parental lines to the chemical. Exposure to a concentration of 0·4 p.p.m. diazinon for 24 h was lethal to susceptible larvae. Close agreement with 1:1 ratios of susceptible: hybrid resistant larvae was obtained when larvae from a repeat backcross series were exposed to 0.4 p.p.m diazinon in each generation. Additionally, there was correspondence between response lines for larvae of backcrosses 1 and 3. This information, plus the recovery of a homozygous-resistant sub-strain by exposure of F2 larvae to a level of the chemical that discriminated against susceptible and hybrid genotypes, suggest that diazinon resistance in the larvae is due to a major allele.

The sexual bahaviour of males of Glossina pallidipes Aust. from the kibwezi Forest Lambwe Valley in Kenya was investigated in the laboratory. Most observatations were on the Kibwezi strain. Three copulatory phases were recorginsed, marked by male courtship, female buzzing, and male jerking with ejaculation. Maturation of copulatory brhaviour occured in advance of ability to inseminate. All males copulated by day 10 and all copulating males inseminated by day 12. Insemination took place only if the jerking phase was present, but neither the occurence of this phase nor the ejection of a spermatophore proved that insemination had taken place. The degree of insemination showed no general relation to age in previously unmated males. The jerking phase was generally shorter in non-inseminating than in inseminating copulations, although duration of copulation showed no obvious relation to the frequency and degree of insemination. The duration of copulation decreased with increasing age of previously unmated males between 10 and 30 days old. Copulation duration was strain-specific while the jerking phase duration was not, suggesting that the length of the pretransmission period (courtship phase plus female buzzing phase) is strain-dependent. In Kibwezi Forest, sexually appetitive (head-down) behaviour among males caught off a moving vehicle was, in geenral, not present among teneral and old males. Head-up and head-down males had small and large amouns of abdominal fat-body, respectively, and both had little gut content. Head-down males had comparatively low activity at dawn and dusk and relatively high middaly activity. The findigs are discussed in relation to the laboratory rearing of G. pallidipes.

Experiments were carried out to determine the effects of the insect growth regulators (IGRs), diflubenzuron and two of its analogues, on adult female Glossina morsitans morsitans Westw. The most effective method of dosing was by topical application, and less pronounced effects followed tarsal contact with treated surfaces and contact during mating with treated males. The compounds had no effect on female length of life or the number of offspring produced, but following topical application at 0·5 μg/female or above, most offspring produced throughout reproductive life (more than 100 days) failed to pupariate. Little difference was detected between the effects of the three IGRs tested. Following the application of diflubenzuron to oviparous insects, egg hatch is inhibited; it is suggested that in the larviparous tsetse fly such compounds act by inhibiting the biosynthesis of chitin at the time of pupariation. IGRs show promise as potential agents for the control of Glossina in the field, and the quantities required would probably not exceed the quantities of insecticides used in current operations against tsetse flies.

Experiments were conducted in Bangladesh in April–July and July–December to study the effectiveness of three methods of insecticide application to three varieties of rice against the stem-borers Scirpophaga incertulas (Wlk.) and Chilo polychrysus (Meyr.). In April–July, seedlings of the varieties IR8 and Dacca-14 were uprooted when 22 days old and treated individually with 0·0375%, 0·075%, 0·15% or 0·3% diazinon (as Diazinon 60 EC), dicrotophos (as Bidrin 85 EC) or carbaryl (as Sevin 85 SP) or 0·3% γ-BHC dust for 12, followed by dipping for 12 h in fresh water and then transplantation. In July–December, the same treatments were applied by controlled irrigation to the seedbeds of the varieties IR8 and Dacca-25 and for 40 h when the seedlings were 24 days old. In another experiment in July–December, granular formulations of diazinon (as Diazinon 5G), dicrotophos (as Bidrin 5G) and Sevidol (a mixed formulation of carbaryl 8G plus γ-BHC 8G) were also applied to the transplanted field at an interval of 20 days. Insecticides applied to uprooted seedlings reduced borer populations more in the case of variety IR8 than in Dacca–14. Diazinon applied at 0·3% to the variety IR8 and Dacca–25 effectively reduced the borer population to 4–8 and 10·5%, respectively, for up to 41 days; γ-BHC applied to the seedbed did not show much response. Dicrotophos was not highly effective in controlling the borers. Granular formulations of Sevidol at 1–5, 2 and 2–5 kg a.i./ ha and diazinon at 2–5 kg a.i./ha controlled stem-borers more effectively in variety IR8 than in Dacca-25. Variety IR8 was found more susceptible to the stem-borers than Dacca-25 and Dacca-14.

During an epizootic of bluetongue virus disease of sheep in Cyprus in the autumn of 1977, 16 species of Culicoides were collected in light-traps and 4 species were collected from breeding sites. Two of the species found breeding in close association with sheep and goats are potential vectors of bluetongue virus. The possibility of a third species being a vector in Cyprus is discussed.

Difficulties were experienced in determining the susceptibility status of populations of Rhipicephalus evertsi evertsi Neum. to organochlorine acaricides. A susceptible strain of this species was found at Maswa, Shinyanga District, Tanzania. Susceptibility for toxaphene, dieldrin and γ–BHC was assessed by means of an FAO recommended test method, the oil-based packet test. A homogeneously responding resistant strain was built up from larvae from Ngong, near Nairobi, Kenya, that had survived a discriminating dieldrin concentration of 0·2%. These showed resistance factors of 10·8 for toxaphene, 30 for γ-BHC and 95 for dieldrin. The F1 cross between susceptible and resistant populations responded homo-geneously and was intermediate in resistance between the parental strains, with resistance factors of 8·7, 9 and 8·1 for ithese compounds, respectively. Larvae from backcrosses of F1 adults with the parental strains showed stepped ld-p lines such as would be expected in a case of inheritance of a single gene allele with partial dominance for resistance. A population of R. e. evertsi near Dar es Salaam, Tanzania, was controlled by application of 0·3% toxaphene despite it having resistance factors similar to those of the F1 hybrids.

The formulation and weathering properties of toxic bait developed for the control of Anoplolepis longipes (Jerd.) in the Seychelles is described. The bait, based on a carrier of sieved coir waste (available locally), was designed to simulate the protein requirements of the ant colony and incorporated yeast extract as a major attractant. It was easy to produce and remained attractive to ants in the field for at least a week under normal weather conditions. The bait could be stored for more than two weeks under ambient conditions in the Seychelles at 23–35°C and 60–95% RH or for about 10 weeks under air-conditioning at 22–29°C and about 60% RH.

Sampling in Northumberland, England, and southern Scotland of pasture soils, the major larval habitat of Hydrotaea irritans (Fall.), showed larvel densities of between 0 and 30/m2; 15 different sites were examined, and all produced larvae. Larvae were found from September until June, larvael development continuing in the soil for about eight months. A study of the distribution within a single field that larvae were not confined to the wooded margins but occurred in significant numbers throughout the field. Higher numbers of larvae were present in the soil beneath cow pats than in the open field, but the proportion relative to the total population is small. Larvae prey was predominantly dipterous and coleopterous larvae. Pupation took place in the top 5 cm of pasture soil during May and lasted until late June. Emergence of adults took place from June until late July; males and females emerged over the same period

The oviposition behaviour of Simulium decorum Wlk., S. vittatum Zett., S. verecundum Stone & Jamnback and S. vernum Macq. is described, with emphasis on the approach by the females to the egglaying sites, the substrates selected and the behaviour of the flies while laying. The eggs and egg-masses of these four species and S. longistylatum Shewell are described; the eggs can be distinguished on the basis of size, and a key is provided to aid their identification. Eggs of S. vittatum completed embryonic development and hatched more quickly than those of S. verecundum of the same age at both 15 and 24°C. The hatch rate of the eggs of both species exceeded 90% when the eggs were present in single-layered masses. The position of an egg Within a multi-layered mass had an important effect on its ability to complete development; significantly lower proportions of eggs of both S. verecundum and S. vittatum in the lowermost layers of large egg-masses hatched, compared with the hatch of those in the top layer. The location of an egg within an egg-mass must be considered a major factor of mortality in the egg stage. The eggs of neither S. verecundum nor S. vittatum were resistant to drying; mortality due to desiccation was related to both the duration of the drying period and the stage of embryonic development when they were subjected to drying.