Schistocerca piceifrons (Wlk.) is the swarming locust of tropical America. It has until recently been confused with closely related species and has usually been misidentified as S. paranensis (Burm.). The biological information that can definitely be attributed to this species is reviewed and is supplemented with some original observations. The invasion area of the locust includes Mexico, Central America, Colombia, Venezuela, Guyana, Ecuador and Peru. Permanent populations are known from the Yuc´tan Peninsula, northern Honduras, the Pacific coast of Central America and the highlands of Peru. There are two subspecies, S. piceifrons piceifrons, known from Mexico and Central America, and S. piceifrons peruviana Lynch Arrib., from Peru. S. piceifrons exhibits phase polymorphism in nymphal colouration and adult morphometrics. The femur length/maximum head width (F/C) ratio is most effective in separating the phases. There are two generations a year. Immature adults of the second generation survive the dry season. Its habitat is subclimax mosaic communities in areas where the natural vegetation is dry tropical woodland. Plagues are believed to have originated when swarms formed in the permanent breeding areas. Records of susceptible crops and natural enemies are given, and the behaviour of hopper bands is described.

The natural predators of Culex pipiens L. and C. torrentium Mart, in artificial containers and ponds were studied in southern England, using serological techniques. The antisera were from rabbits immunised by injections of saline extracts of the species of Culex into the inguinal lymph nodes and made relatively more specific by absorption. The gut contents or whole individuals of 1098 potential predators were smeared on to filter paper and tested. The most important predators in the ponds were Odonata nymphs while those of artificial containers were larval Dytiscidae. Diptera and Araneae preyed on emerging adults. The length of time a mosquito meal remained detectable in the gut of predators varied from a minimum of 8 h for the newt Triturus vulgaris to 24 h for the zygopteran Ischnura elegans (van der Linden). The results of laboratory tests indicated that the anisopteran Sympetrum striolatum (Charp.) was potentially more important as a biological control agent for larval culicines in ponds than the zygopteran Coenagrion puella (L.).

From estimates of the most likely egg–laying dates of 53 outbreaks of Spodoptera exempta (Wlk.) in East Africa, and from estimates of the likelihood of rainstorms (20 mm or more a day) at the outbreak sites around those dates, it is shown that concentrated laying by moths leading to outbreaks early in the season (January to March) in 1974–75 was associated with rainstorms at the time of oviposition. However, there was no such association in April and May. The mechanism of association is unknown; moths may be concentrated whilst airborne, or they may reach and stay in limited areas wetted by rain, where new grass growth might be expected.

Species records of Sphingidae taken in Trinidad were kept from 1968 to 1979. Seventy–five species and one subspecies were taken, including several new records for the island. The numbers of sphingids taken in Robinson light–traps equipped with 125–watt mercury–arc lamps were recorded over a period of eight years at St. Augustine, Trinidad, and the data analysed. The species abundance distribution was found to be well–fitted by the log–normal series. Data were examined for trends and periodicities, and the variance was found to be largely accounted for by three principal factors. A long–term decline in catch was observed in one trap due to the growth of screening vegetation. Annual variation in catch was found to correlate with the annual pattern of precipitation, with higher catches during the rainy season, although some species differences were detectable. Monthly variation in catch was found to correspond with the cycle of lunar illumination, being significantly depressed with increasing brightness. Interspecific differences in the response to moonlight were also detected. The influence of screening effects on the observed periodicities is discussed in relation to the siting of the traps. Times of commencement of flight activity were recorded, and the relationship between time of capture and activity is discussed. Apart from one species, the sex ratio of captured sphingids was significantly male-biased. Data from three traps were compared with each other and with those from other tropical locations.

In order to see if aeration causes grain beetles to become peripherally distributed in bulks of grain, the positions of adults were recorded 7–10 days after they had been placed in the middle of vertical columns of wheat 1200 mm long and 80 mm in diameter. The columns were held at 10 or 25°C, and a downward current of air was passed through half of them. At 10°C, there were more adults of Oryzaephilus surinamensis (L.) at the ends and fewer at the centre of aerated than unaerated tubes when a high airflow was used, and at 25°C, a similar difference occurred when aeration caused cooling, dampening or drying of the grain. Dampening at 10°C and drying at 25°C caused there to be fewer adults of Sitophilus granarius (L.) at the ends and more at the centre of aerated than unaerated tubes. However, vibration at 10°C encouraged the dispersion of weevils. Rhyzopertha dominica (F.) scarcely moved at 10 or 25°C under either aerated or unaerated conditions.

Biological control of Aonidiella aurantii (Mask.) is notoriously difficult in the hot lowlands of Swaziland and the eastern Transvaal. In view of resistance to organophosphates in populations elsewhere in the Transvaal, there is renewed interest in the commercial application of integrated pest management on citrus. Accordingly, data from a population of A. aurantii on orange trees in the Swaziland lowlands were examined to answer questions about biological control of the pest in this climatic region. Sections of the population on twigs and fruit were treated separately, and that on the leaves was ignored as not contributing much to the economy of the whole. The infestation of fruit each year depended largely on the size of the infestation on twigs in November (early summer), when crawlers from twigs first colonised the fruitlets. Mortality on twigs was estimated, checked from predictions of the recruitment rate and related to indices of climatic and biotic factors; 73% of the variation was described by mean predator intensity, mean minimum temperature and excess rainfall above the long-term mean, all measured over the generation time. On fruit, 32% of the variation in mortality was described by mean maximum saturation deficit in the generation time, the relationship being inverse. The dryness of the lowland climate appeared to be its favourable characteristic. The population appeared to be regulated about a mean level which was unacceptably high. Predators were the most effective natural enemies, probably followed by parasitoids (Aphytis spp.) on fruit. Endoparasitoids were probably ineffective.

A colony of Glossina morsitans morsitans Westw. was established in the laboratory in Tanga, Tanzania. After being expanded to the planned level of 60 000 flies, the stabilised colony was used to support a field trial using surplus males that were sterilised and released. The production system consisted of an adaptation of the in vivo rearing techniques developed at the Tsetse Research Laboratory, England. Goats were hosts for 90 % of the production; the balance was fed on rabbits. Techniques were developed to standardise the pupal off-take from stabilised colonies in each of three separate insectary units. Puparia were collected daily and kept separately until 52% emergence had occurred; these emerging flies, mostly females, were used to replenish the stock colony as needed. Further eclosion was prevented by chilling the remaining puparia (mostly males) quickly at 4°C and then storing at 10 ± 1°C for up to four days prior to irradiation and shipment to the field. About 68 % of the males produced were available for sterilisation. During the 15-month period of production in support of the field experiments, 1·3 million puparia were produced; 0·6 million of these puparia were released at a production cost of $220 per thousand.

Surplus puparia from a colony of about 50 000 females of Glossina morsitans morsitans Westw. provided males for sterilisation and release in an experimental assessment of the sterile insect technique in Tanzania. Excess males were stored late in the puparial stage at 10 ±1°C for up to four days prior to being irradiated at ambient temperatures in a nitrogen atmosphere with 11·8 krad in a radioactive caesium (137Cs) source. Puparia chilled at 8 ± 1°C were transported to the field release area twice weekly for manual release. At the release sites, the adults emerged synchronously within 60 min and were automatically marked as they crawled through sand containing fluorescent powder.

The flight performance of three cytospecies from the West African complex of Simulium damnosum Theo. was tested under controlled laboratory conditions. A total of 293 individuals (174 of S. squamosum (End.), 65 of a new form of the subgroup of S. soubrense Vajime & Dunbar and S. sanctipauli Vajime & Dunbar and 54 of S. sirbanum Vajime & Dunbar) was tested on 526 occasions, of which 380 involved sucrose-fed insects, 65 water-only-fed insects, of both sexes, from laboratory-emerged stock and 81 blood-fed, wild-caught females. A high percentage of tests resulted in flights. Frequency distributions of both flight duration and distance flown were skewed, more flights being of short than of long duration. Sucrose-fed females and females caught wild at human bait generally flew well. Insects given access to water only made short flights, but S. sirbanum flew fairly well under these conditions. The recorded maximum flight durations and distances were 262 min (in a male) and 5·25 km (in a female) in S. squamosum, 282 min (in a male) and 6·15 km (in a male) in S. soubrense/sanctipauli, and 186 min (in a female) and 5 27 km (in a female) in S. sirbanum, all from sucrose-fed groups. Some insects were flown on several days up to 11 days after emergence. Some insects made long flights on one day but not on others. Further long flights could be induced on the same day if the insect was allowed access to sucrose solution prior to retesting. These results are discussed in relation to previous findings from S. ornatum Mg. s.l. and to the migration potential of the important vectors of onchocerciasis in West Africa.

A large–scale mating disruption trial for the control of Pectinophora gossypiella (Saund.) was carried out in the Fayoum Province of Egypt during the 1981 cotton season. Two areas, each of 50 ha, were sprayed with a microencapsulated formulation of the sex pheromone (a 1:1 mixture of (Z, Z)- and (Z, E)-1, 11-hexadecadienyl acetate) as the sole means of controlling this pest. Five applications of 10 g a.i./ha were made during the season using fixed-wing aircraft. The pheromone treatments were compared with conventional insecticide spray treatments in two other 50-ha areas of cotton. From comparisons of treatments in terms of various plant damage criteria including the percentage of rosetted flowers, percentage boll infestation, gross yield of seed cotton and lint quality, it was concluded that the pheromone treatment was equal in effect to the insecticide sprays.

Sticholotis chittagongi sp.n., reported as feeding on aphids infesting Ziziphus mauritiana in Bangladesh, is described. It is compared with S. amator Kapur from which it differs in size, shape of pronotum and male genitalic characters.

The insect-pathogenic fungus Metarhizium anisopliae caused heavy mortality in laboratory groups of the Australian termite Nasutitermes exitiosus (Hill) to which infected workers had been added. Conidia of M. anisopliae started an epizootic when introduced into field colonies of N. exitiosus near Canberra, irrespective of whether the termites were treated by dusting or spraying in the mound itself, or dusting in nearby feeding sites. In some cases, the disease persisted for at least 15 weeks, and by this time few healthy termites could be found in almost half the treated colonies. Samples of workers taken from treated colonies showed high levels of contamination by Metarhizium, irrespective of the state of the colony, but the factors that inhibited the completion of fungal development in the nest are unknown.

The association between weather and light-trap catches of Spodoptera exempta (Wlk.) was examined for four traps in East Africa, using whole–night catches and several years' data. Large increases in trap catch were found to be (1) significantly associated with rain at all four traps for the period December–March, but not for later in the season; (2) significantly associated with light wind periods at Muguga for December–May, but not later in the year, and not at Nakuru, due to the very high overall frequency of light winds there; and (3) not significantly associated with windshifts at either Muguga or Nakuru. These results suggest that high densities of flying moths, which may give rise to caterpillar outbreaks early in the year, often occur where the rather infrequent early–season rains fall.

On guava trees at Nelspruit, South Africa, there was a mutualism between the ant Anoplolepis custodiens (F. Sm.) and the mealybug Planococcus citri (Risso), which raised the population levels of both. When ants were excluded from half the trees, their overall population level also dropped by half. Further, they moved their nests to be as near as possible to their main food source, the honeydew of the mealybugs. When deprived of their ant mutualists, the mealybugs were heavily preyed on by coccinellids such as the ant–intolerant Exochomus flavipes (Thnb.) and the ant–tolerant Scymnus spp. Later, the mealybugs were almost totally eliminated by the primary entomogenous fungus Cladosporium sp. near C. oxysporum. The coccinellids, now without food, were forced to abandon the trees. In contrast, in trees where ants were allowed to continue their normal activity, the epizootic among the mealybugs was delayed by 14 days. This limitation by the ants of disease allowed a basal but fragmented mealybug population to survive. As the mealybugs declined, the ants switched to attending the aphid Aphis gossypii Glov. Fifteen days after the epizootic struck the ant–attended mealybug population, it began to devastate the aphid population. With both mealybugs and aphids at a low level, the ant population declined. However, the ant–homopteran mutualisms, although severely hit by the epizootic, nevertheless remained intact.

Experiments are described in which age-specific survivorship and fecundity of Sitophilus oryzae (L.) were determined over a wide range of environmental conditions (15·0-32·3°C and 11–14 % grain moisture content). The data derived from these experiments, together with some previously published data, were used to develop mathematical submodels for these processes. The models are continuous functions of time, grain moisture content and grain temperature. Rates of increase per week and per generation were calculated for the range of environmental conditions used. The results are discussed in relation to previously published work, and the potential usefulness of the submodels is discussed briefly.

Studies on the precision levels and efficiencies of available insect suction samplers (D-Vac and FARMCOP) were undertaken in the Philippines to determine the best possible sampling procedure to derive absolute population estimates of delphacids, cicadellids and their predators in flooded rice. The D–Vac suction sampler when used in conjunction with an enclosure placed over the rice hill prior to sampling was found to be the most suitable. The sampling procedure adopted is described in detail, and sampling efficiencies for the D–Vac are given for nymphs and adults of the delphacids and cicadellids and their predators. These values could be used by other workers following the sampling procedures described here on modern rice varieties grown under flooded conditions to achieve absolute population estimates.