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.

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.

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.

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.

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.

Bait containing 1% a.i. aldrin and used at a rate of 10 kg/ha gave good control of Anoplolepis longipes (Jerd.) in the Seychelles, especially when large areas were treated. Typically, 90% or more of the ants were killed, usually within the first few days. Depending on the area baited, population recovery took at least 3–12 months and was largely by re-invasion from untreated areas. The bait was relatively specific but chickens starved for 24 h would eat it when no other food was available. It is concluded that baiting is relatively inexpensive and provides a safe method of controlling infestations of A. longipes over large areas.

A study was made of the seasonal variation in population density of larvae of Boophilus microplus (Can.) in four locations in Jamaican pastures where the mean annual precipitation ranged from 59 to 222 cm. Variations in population density were related to rainfall. Generally, four months of heavy rains in August to November preceded significant increases in B. microplus populations in December to February. This was followed by a reduction then another slight increase, resulting in a bimodal pattern of activity. Although populations fell to very low levels by the end of the dry season, only in one focus were they depleted to undetectable levels.

Anastatus umae sp. n., a parasite in the oothecae of two Indian species of cockroaches, mainly of Neostylopyga rhombifolia (Stoll), is described. It is assigned to Cladanastatus subgen. n. of Anastatus, based mainly on the branched antennae in the male and on some less conspicuous characters of the female. Eupelmus leithi Wlk., another Indian species, is transferred to Anastatus. In addition, two other parasites of Indian cockroaches, Tetrastichus hagenowii (Ratz.) and T. asthenogmus (Wtstn.), which were confused as a single species, T. hagenowii, in the synopsis of the cockroaches and their parasites by Roth & willis in 1960, are separated.

The overwintering of Heliothis armigera (Hb.) was studied in the Namoi Valley, north-western New South Wales, Australia. In field observations, over 80% of pupae formed during late April and May were found to be in diapause and did not resume development until September. Moth emergence from diapausing pupae occurred in a protracted period between September and November. Laboratory studies indicated the probability of two phases of diapause development, one completed under cool soil conditions of winter and a second requiring a temperature above about 17° C. The threshold of the second phase was higher than that for non-diapausing pupae and was not normally reached until late September. The times to diapause termination in populations of overwintering pupae were satisfactorily fitted to a geometric distribution, which was reflected in the protracted emergence period of moths in field cages. The limited availability of suitable host-plants for the overwintering generation and for emerging moths is discussed.

The flight activity of adult Delia coarctata (Fall). was studied on Rothamsted Farm from 1969 to 1977 using light-traps. These catch, almost exclusively, dispersing mature females, more being caught at full moon than at new moon. Dispersal begins in response to an acceleration in the rate of decrease of daylength, and at Rothamsted begins on 10 July, soon after the rate of decrease accelerates. Maturation of eggs is controlled by temperature; at Rothamsted, the first mature females appear when temperature accumulation above 5° C has reached 314·5±10·5° after 12 June. Maturation usually coincides with dispersal, but females that have matured before 10 July do not disperse until after that date. Catches of females in light-traps are correlated with the numbers of emerging females per hectare and the numbers of eggs per hectare. Light-traps could be used as a simple way of forecasting numbers of eggs early enough to give advice on seed treatment for winter wheat on land subject to attack by D. coarctata.

The feeding rate of nymphs of Paulinia acuminata (Deg.) on Salvinia molesta was studied in the laboratory using single nymphs on different numbers of Salvinia leaves. Each successive instar ate more plant tissue, but at population densities likely to occur in nature it was unlikely that consumption rate could match the natural Salvinia growth rate. The controlling effect of Paulinia on Salvinia in Lake Kariba, Rhodesia, may therefore be negligible.

Loss rates of (Z)-8-dodecenyl acetate and related compounds from various dispensers were compared at 15, 20 and 29° C in the laboratory. Comparisons were also made of the performance of these dispensers in pheromone disruption trials against Cydia molesta (Busck) in peach orchards in Australia, in terms of the reduction of male captures at pheromone traps. Hollow-fibre and polymeric-laminate dispensers were superior to various polyethylene and silicone-rubber designs in providing a relatively constant release of pheromone in time, at rates readily modified by altering the dimensions of the dispensers.

Growth of the food fungus of the leaf-cutting ant Atta cephalotes (L.) on extracts of plants selected by the ants was shown to be affected by the plant species, the pH of the extract, the concentration of the sap or plant extract and pretreatment of the substrate by the ants. It was not possible to establish an unambiguous relationship between the rate of growth of the fungus on leaf extracts and the foraging preferences of the ants for the leaves. There were indications, however, that the fungus grows most rapidly on extracts of plant material preferred by A. cephalotes. Relative growth rates of the fungus on different substrates may be related to the presence of growth inhibitors rather than to nutrient availability.

Heliothis armigera (Hb.) has been shown to develop continuously in tropical areas but to become more dependent with increasing latitude on a pupal diapause to survive the winter. The changes that occur in pupal period under ambient conditions in Botswana were examined. Pupae formed in May were able to survive the winter period and produce adults in September. Laboratory work using artificial environments showed that this extended pupal period is not simply a response to low pupal temperatures but is induced by the low temperatures and short daylengths experienced by the larva. Pupae from larvae reared at 27° C and a 14-h daylength (non-diapause pupae) initiated adult development even at 13° C. Pupae from larvae reared at 18° C and a 9-h daylength (diapause pupae) had similar pupal periods to non-diapause pupae at 33 and 27° C. However, at 18 and 13° C, diapause pupae had much longer developmental periods than non-diapause pupae. More diapause pupae were produced at 18° C from larvae reared in a 12-h daylength than from those in 15- or 9-h daylengths. The variation and importance of this temperature-labile facultative diapause over the extensive geographical range of H. armigera is discussed.

Detailed taxonomic studies of adult Cecidomyiidae reared from inflorescences and seed-heads of species of Gramineae and Cyperaceae during field surveys in Queensland and the Northern Territory of Australia in 1970–73 established that Contarinia sorghicola (Coq.) is restricted to non-indigenous crop and weed species of Sorghum section Sorghum that have been introduced to Australia by man and that three morphologically distinct species of Contarinia occur on native Australian grass species of Sorghum section Parasorghum. An earlier report that the wild grasses Dichanthium, Bothriochloa and Eriochloa serve as alternative hosts of C. sorghicola was not confirmed by detailed examination of long series of specimens reared from these hosts, nor was the pest species found on any other genera of Gramineae. It is therefore concluded that, in Australia, C. sorghicola has been spread (probably in contaminated seed) and maintained by grain and forage sorghums and that wild grasses are not potential sources of crop infestation. Eleven new species are described: C. roperi sp. n. and C. plumosi sp. n. from Sorghum plumosum; C. intrans sp. n. from S. intrans and S. stipoideum; C. sehimae sp. n. from Sehima nervosum; C. bothriochloae sp. n. from B. bladhii; C. dichanthii from D. annulatum var. fecundum and D. tenuiculum and possibly from D. affine and D. sericeum; C. passlowi sp. n. from D. annulatum var. fecundum; C. alloteropsidis sp. n. from Alloteropsis semialata; C. brevipalpis sp. n. from Eragrostis brownii; C. scirpi sp. n. from Scirpus lacustris and C. fimbristylis sp. n. from Fimbristylis bisumbellata. Characters of the female cerci were especially useful in diagnosing species, making it easier to identify females than males. Cecidomyiids of the genus Geromyia were reared from Setaria and cecidomyiids of the genus Lasioptera were reared from ten grass genera and one sedge genus during the surveys, but this material is not dealt with in detail. The needs for further field work and taxonomic studies are stressed and it is suggested that apertures on the dorsal surface of abdominal segment VIII in female C. sorghicola may be the openings of sex pheromone glands and would merit further detailed investigation.

An incomplete ring of electrified nets was placed round a trap or round an electrified net and visual target in woodland infested with Glossina morsitans morsitans Westw. and G. pallidipes Aust. in Rhodesia. The distribution of catches in these systems was used to estimate the minimum efficiencies with which the trap or net and target captured flies that were initially attracted by odours derived from a herd of cattle hidden below ground. With mature tsetse, the estimates for the trap were 23 and 21% for male and female G. morsitans, respectively, and 70 and 49% for male and female G. pallidipes. For the net and target, the corresponding figures were 29, 30, 53 and 43. The coefficient of variation of such estimates (about 10%) was low enough to suggest that the technique affords a quick and reliable means of screening the efficiency of many trap designs. Factors responsible for the efficiency of the trap were elucidated. Data for other insects were obtained.

The causes of fluctuation and stabilisation in a population of Andraca bipunctata Wlk. on tea in India were assessed over three years using the technique of key-factor analysis. Failure to produce the maximum complement of eggs, together with female mortality and adult migration, is shown to be the key-factor. Other mortality factors include non-viability of eggs and parasitism of the caterpillars by the tachinid Cylindromyia sp. Mortality of the female pupae tends to stabilise the population by compensating for losses due to the key-factor, but neither this nor any other mortality factors appear to be significantly density-dependent. The need for devising specialised sampling procedures and statistical tests for tropical insect populations is discussed.