The control of Simulium has always relied largely on the use of insecticides against the larvae, and this is the case in the current large-scale Onchocerciasis Control Programme against the vector S. damnosum Theobald in West Africa. Resistance to temephos has occurred in some vector species, and it is necessary to find alternatives to this preferred larvicide. In order to provide a frame of reference for the development of new larvicides or formulations, the literature relating to larval filter-feeding behaviour is first reviewed in detail. Then the physico-chemical conditions in larval habitats are outlined. The types of formulations and classes of insecticide used in Simulium control are considered, with particular attention being given to emulsifiable concentrate formulations and the reasons for their effectiveness. Particulate formulations, which have been recommended on environmental grounds, are also discussed. Techniques used in the screening of larvicides are considered, and it is concluded that flow-through systems are necessary; mini-gutter tests conducted using water and fauna from rivers to be treated are to be strongly preferred, followed by stream trials. Knowledge of Bacillus thuringiensis var. israelensis as a Simulium larvicide is reviewed in detail. The environmental impact of control of Simulium larvae, both in the tropics and the temperate zone, is extensively reviewed. Throughout, key features which might lead to improved larvicide formulations and testing procedures, together with serious gaps in our knowledge are emphasized.

Reduction in growth of saplings of Eucalyptus deglupta resulting from die-back caused by Amblypelta cocophaga China was studied in forestry plantations in the Solomon Islands. At a standard spacing of 10 × 3 m, a comparison was made of tree growth and incidence of A. cocophaga attack on saplings planted in strips 2 m wide cut through secondary forest, with those from which all inter-row vegetation was cut back prior to planting. Initially, a greater proportion of trees was infested on the cleared than the uncleared plots, but at the end of the first year, at which time the attack was at its peak, no differences could be detected. From the fifth to the thirteenth month after planting out, uninfested trees on the cleared plots increased in height at an average rate of 60 cm per month. For every week that at least one A. cocophaga was recorded on a tree, this rate was depressed by 1·3 cm. On the uncleared plots, the average rate of increase of uninfested trees was only 42 cm per month and this was reduced by 1·0 cm for every week that an insect was recorded. By the end of the first year, an estimated 37% (in cleared plots) and 41% (in uncleared plots) of the potential stand was rendered useless for future timber production due to A. cocophaga damage. In terms of total stem volume (not log production), about 1 m3/h out of a potential 3 m3/h was lost in the uncleared plots and 0·2 m3/h out of a potential 0·6 m3/h in the uncleared ones. Whilst clearing did not reduce the incidence of A. cocophaga attack, the advantage of clearing in terms of increased tree growth was considerable.

Nine types of plastic ear tags impregnated with organophosphorus, amidine or synthetic pyrethroid compounds were applied to both ears of groups of five Maasai zebu cattle in Narok District, Kenya, and grazed together with five untagged cattle to which no acaricides were applied. Most of the tag types gave highly efficient control of Rhipicephalus appendiculatus Neumann attaching to the head and ears of the cattle, which lasted up to 160 days after application and often completely prevented tick engorgement. All the chemical groups were effective. The most effective tag was a combination of amitraz and permethrin which gave better control than either chemical on its own. Control of Boophilus decoloratus (Koch), Amblyomma cohaerens Dönitz, A. variegatum (F.) and R. evertsi evertsi Neumann attaching to the bodies of cattle was less effective, although most of the tags exerted some effect. Rainfall appeared to reduce the degree of control by the tags. A role for such impregnated ear tags for the control of cattle ticks in Africa is suggested.

Four species of hypogeic mealybugs are known to infest African violets (Saintpaulia spp.). These are Rhizoecus americanus (Hambleton), R. cacticans (Hambleton), R. dianthi Green and R. saintpauliae sp. n. The last species has some striking characters and is described here from specimens from S. ionantha in a nursery in Thailand. None of these species is known to occur on plants in their natural habitat, the mountainous areas of Kenya and Tanzania, where the survival of most of the 20 species of Saintpaulia is threatened. Although infestations of R. dianthi on African violets may be severe, the mealybugs only affect these and other potted plants in the extensive horticultural trade. A key is provided to separate the four species.

Mating disruption of Cydia molesta (Busck) was attempted by treating, with pheromone, all orchards in a small but discrete peach-growing district in New South Wales for two successive years. In the final year of the trial, two former control orchards were also treated with pheromone. The efficacy of the treatment was examined by monitoring fruit and shoot damage, male captures in pheromone traps, captures of both sexes in feeding lures, mated status of wild females and numbers of immature stages in trap bands. It was concluded that mating disruption was a viable alternative to conventional insecticides.

A semi-defined synthetic diet for Glossina spp. was developed and used successfully to rear G. palpalis palpalis (Robineau-Desvoidy) for five generations. The survival, fecundity and offspring size achieved were similar to those obtained when flies are fed on whole blood in vitro. The diet was also tested on G. morsitans morsitans Westwood, G. austeni Newstead and Stomoxys calcitrans (L.), and in all cases was satisfactory. The diet consists of commercially available ingredients and is the first such diet to be developed for obligate haematophagous insects.

Adult females of Panolis flammea (Denis & Schiffermüller) in the laboratory laid more eggs on some provenances of lodgepole pine (Pinus contorta) than on others, even when offered no choice. Their preoviposition period was inversely related to the suitability of the host for larval growth and development. The shorter the preoviposition period the greater the number of eggs that were laid. Delayed mating resulted in reduced fecundity and reduced egg fertility. Female moths lived longest on those hosts on which they oviposited most. Oviposition preferences were correlated with the ratio of the two monoterpenes α- and β-pinene within the host-plants. The effects of provenance, delayed mating and adult mortality were demonstrated through a simulation model; the effect of delayed mating was particularly marked when adult survival was poor. Egg production in the field in Scotland varied from 30 to 123 eggs per female, but this variation could largely be explained by spring temperature. It was concluded that this relationship was due to the influence of temperature on mating and egg laying. The relationship between temperature and egg production forms a basis for predicting damaging levels of Panolis flammea from either pupal or adult numbers. The effects of provenance and delayed mating demonstrate that the frequency of P. flammea outbreaks in the UK may be reduced by the planting of less preferred lodgepole pine provenances and by mating-disruption methods.

Data are presented from five series of 240 adults of Rhipicephalus appendiculatus Neumann kept in the laboratory, in which a steady decline in the numbers of granules in e cells of type 3 acini of the salivary glands occurred. This was readily detected in whole gland preparations of the salivary glands stained with methyl green and pyronin, and the same specimens could be used for detecting Theileria parasites in the salivary glands. Characteristics for grading these ticks into three physiological age grades are given, and a formula is provided for incorporating the age grade with infection rate. This gives a value for comparative estimates of the challenge posed by field populations of ticks for the transmission of Theileria to cattle.

Aedes lineatopennis (Ludlow) is thought to be a vector and maintenance host for Rift Valley fever virus in Kenya and perhaps other parts of sub-Saharan Africa. Immature examples are often found in tremendous numbers in restricted, low lying habitats known as dambos. A dambo in Thika District, Central Province, Kenya, was artificially flooded to simulate the conditions occurring when this area naturally floods and induces the hatch of A. lineatopennis eggs. Observations on the dispersion and survival of the emerging adult population were made at a time when no other adult A. lineatopennis populations existed. More than 10% (87 511) of the estimated A. lineatopennis adults that emerged from the flooded dambo were collected during a 45-day period. The overall mean distance travelled by males in the 45 days after emergence was only 0·07 km. Female dispersal was interrupted but generally was with the prevailing wind. The overall mean distance travelled by females in the 44 days after emergence was 0·15 km. Mortality of both males and females was independent of age. The high daily survival rate of males (0·83) was not significantly different from that of the females (0·85).

Phenacoccus avenae Borchsenius, a mealybug described originally from beneath the leaf sheaths of a grass in Armenia, USSR, has been intercepted at quarantine in the Netherlands. USA and England on bulbs, corms and rhizomes of ornamental plants from Turkey. The mealybug, however, has never been recorded from Turkey although it probably exists there on monocotyledons. It is redescribed and illustrated here to facilitate identification at quarantine stations, and a list is given of its host-plants in the families Gramineae, Amaryllidaceae, Iridaceae and Liliaceae.

Wavelength dispersive X-ray fluorescence spectrometry was used to make quantitative determinations of the elemental composition of adults of Agrotis segetum (Denis & Schiffermüller) that had been reared on one of eight soil-plant combinations or a semi-synthetic diet. Robust-means principal components analysis (RMPCA) of the data for eight elements and all treatments (except for the semi-synthetic diet) separated the means of the groups by soil type, irrespective of host-plant. However, individuals could not be separated until the data were grouped into the two host-plant sub-sets. The main discriminant, Al, was of doubtful validity and was therefore excluded from the data which were reanalysed by RMPCA. This failed to discriminate either group means or individuals until each host-plant sub-set was analysed separately; then, individuals could be differentiated by soil type although not as distinctly as when Al was included in the data. There was, however, a clear separation of the sexes because of a higher content of K and lower content of Ca in females; these two elements, together with S and Cl, were the main discriminants of soil type. It is concluded that larval host-plant is a significant factor in the elemental composition of adults of A. segetum but limiting and confounding in respect of identification of soil type and, therefore, geographical source. This conclusion probably applies also to other similar polyphagous species, but specific differences in biology and behaviour may influence the applicability of the technique to field studies.

Crosses were made between the three subspecies of the complex of Glossina morsitans Westwood and the hybrid females backcrossed. Hybrid female fecundity was highly ‘reactive’ to foreign male genes when the mother was G. morsitans centralis Machado compared with the reciprocal crosses and backcrosses. Hybrid F1 males were unable to inseminate females successfully, and although in nearly a quarter of the dissections sperm was transferred to the uterus, it did not migrate to the spermathecae. Heterozygosity between the X- and Y-chromosomes and most of the autosomes led to high frequencies of sterile males, but homozygosity between the X- and Y-chromosomes could still yield 30–50% sterility. Successive backcrosses of hybrid females between G. m. morsitans and G. m. centralis to the latter subspecies continued to increase the frequency of fertile males. Interactions between X-chromosome and autosomal gene seemed to be responsible for hybrid male sterility, and the number of sterility genes involved appeared to be very few. Crosses involving G. morsitans submorsitans Newstead generally agreed with those between the other two subspecies, but the distortion in the sex ratio of emergent adults limited the application of the data to this subspecies. Competition experiments using sterile hybrid males and fertile males in population cages (30 cm cube) showed that suppression was possible, especially when the ratio of sterile:fertile males was 2:1. The value of stetile hybrid males in tsetse control programmes and the evolution of reproductive isolation in the complex is discussed.

Radar methods have been extended to measure the aerial density of small insects. Results obtained during an outbreak of the cereal aphid Metopolophium dirhodum (Walker) in south-eastern England were compared with simultaneous suction trap catches to study the sensitivity of trap effectiveness to windspeed. Two traps were studied: the Rothamsted Insect Survey trap (12·2-m) and a standard aerofoil trap. The Survey trap effectiveness is moderately sensitive to windspeed, decreasing exponentially by a factor of two for each 2·4 m/s (5 knots) of average windspeed. The two trap sensitivities did not differ significantly, but both results are very significantly different (P>0·001) from the published predictions, which were based upon a comparison of catches from suction traps and a combination of a rotary (whirligig) net and a tow net. These differences are discussed. The average catching rate is about 40% of that of an ideal trap. Seven-day catches could vary by a factor of 0·5—2·0 from average due to prolonged periods of extra strong or light winds. Systematic windspeed gradients can corrupt suction trap studies of insect dispersal in relation to vertical density profiles, diurnal flight patterns and geographical distribution. Absolute calibration of the aerofoil trap was achieved by using the remote-sensing IRADIT infra-red system to measure the aerial density of aphid-size insects near to the trap inlet in very light winds; the effectiveness was not statistically different from unity, and the Survey trap is expected to perform similarly.

Experiments were carried out in a slow speed wind tunnel and in a moving air observation chamber on anemotactic and visual responses of Stomoxys calcitrans (L.). An increase in carbon dioxide concentration elicited an anemotactic response, which was enhanced by odours from expired human breath and odours from a live guineapig. Acetone vapour also elicited an anemotactic response, but acetic acid was repellent. The response to visual targets increased in proportion to the increase in flight activity induced by raising the concentration of carbon dioxide in the airstream. Cattle sebum had an arrestant effect but also elicited further searching activity.