Illustrated descriptions of galls, larvae, pupae and adults, with a diagnostic key, are given for five species of Psectrosema Kieffer (= Amblardiella Kieffer = Isosandalum Kieffer) collected from various species of Tamarix during field surveys of potential biocontrol agents undertaken by the Commonwealth Institute of Biological Control in Pakistan. The genus Psectrosema is re-defined and the eleven species previously described from Europe, North Africa, India and Kazakhastan, USSR, are listed, mostly as new combinations. The five species recorded from Pakistan are P. manü nom. nov., stat. rev., comb. n. (= tamaricis Mani) from T. dioica; P. indicum sp.n. from T. indica; P. reticulatum sp.n. from T. hispida, T. androssowii and T. arceuthoides; P. unicornis sp.n. from T. dioica; and P. parvum sp.n. from T. indica.

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.

A major component of the sex pheromone of Dacus oleae (Gmel.) has recently been identified as a spiroacetal. The use of this compound as a lure for use in the development of a monitoring trap for that species is described. Polyethylene vials gave a slower release rate of the spiroacetal than rubber septa or microfibres, but even in polyethylene vials a loading in excess of 10 mg was required (optimum 20 to 25 mg) to obtain catches in delta traps which were comparable with those in unbaited vertical yellow sticky traps. In studies in an olive grove near Granada, Spain, a 25-mg spiroacetal lure used with a vertical yellow trap gave catches of males of D. oleae which were four times as great as those in delta traps with the same lure or in unbaited yellow traps. The height of the trap had no apparent effect on catch. Previously recorded components of the sex pheromone did not prove to be effective when combined with the spiroacetal. Combined monitoring of Prays oleae (Bern.) and D. oleae, using their respective pheromones in the same trap, appears to be feasible with delta traps.

The effect of parasitism by the aphidiid wasp Aphidius uzbekistanicus (Luzhetski) on the isoenzyme banding patterns of 14 soluble enzymes separated by one–dimensional slab polyacrylamide gel electrophoresis from crude homogenates of its main host, Sitobion avenae (F.), are described. Parasitism was found to be detectable using any 12 of these enzymes. The differences observed between the banding patterns for three enzymes (ester–ase, malate dehydrogenase and malic enzyme) separated from the adults of five primary parasitoid species attacking this aphid (A. picipes (Nees), A. uzbekistanicus, Ephedrus plagiator (Nees) Praon volucre (Hal.) and Toxares deltiger (Hal.)) are also described. Esterase was found to be the best enzyme for taxonomic differentiation of all aphidiid species examined. The use of electrophoresis for assessing percentage wasp parasitism in integrated management studies of cereal aphids is discussed.

The galls induced on Tamarix spp. in Pakistan by six species of Psectrosema are described, and the known host ranges and geographical distributions of these species are given, together with information on seasonal biology and adult behaviour based on field surveys and laboratory observations. Parasitic Hymenoptera and other insects associated with the galls are listed.

In the field in India, most eggs of Chilo partellus (Swinh.) hatched in the morning soon after first light. Laboratory experiments show that in continuous light hatching occurs after 250 hour-degrees of development above 12°C from the time at which the head capsule darkens (blackheading). Hatching may be advanced by a lights-on stimulus or retarded by darkness, and these effects account for the extensive hatching at dawn. Hatching is not entrained by a circadian rhythm. The significance of hatching at this time of day is discussed.

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.

Baseline toxicity measurements established discriminating concentrations of pirimicarb and demeton-S-methyl guaranteed to kill susceptible examples of Aphis fabae Scop., Sitobion avenae (F.), Metopolophium dirhodum (Wlk.) and Rhopalosiphum padi (L.) in the dip-test, the FAO-recommended method for detecting resistance in aphids. There was no evidence for resistance to either insecticide in field-collected populations of aphids from various parts of the UK or amongst variants of S. avenae characterised by staining their esterases after electrophoresis. New, simple techniques for rearing large numbers of colonies of cereal aphids are described.

The occurrence of the African ichneumonine Ctenochares bicolorus (L.) in Australia and New Zealand as a parasite of the crop pest Chrysodeixis chalcites (Esp.)/C. eriosoma (Dbd.) is reported. The advent of the species to Australasia is discussed in relation to the known distribution and host associations of the genus.

The development of adults of Nilaparvata lugens (Stål) reared on one susceptible and one resistant variety of rice plants of different ages was compared. Throughout the range of plants tested there was an overall trend for the newly moulted adult to synthesise and store a reserve of lipid and to lose most of the stored glycogen accumulated during the nymphal stage. N. lugens has two wing morphs, and whilst lipid deposits were greatest in the macropterous ‘migrant’ males, in females it was the brachypterous ‘reproductive’ insects that had the highest lipid deposits and also the greatest residual body weight. However, because of their lower body weight, the macropterous females had the greater percentage of lipid. Both flight willingness and the percentage of macropterous females showing flight-orientated physiological development increased with the age of the host-plant. Both survival and migration potential were lower in insects reared on the resistant rice variety compared to those reared on the susceptible variety. The pattern of post-flight resynthesis of fuels suggests that more than one major migration is unlikely.

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.

The collective orientation of Chortoicetes terminifera (Wlk.) migrating at night in New South Wales was studied with a radar. Measurements of the distribution of insect echoes on the radar's plan-position-indicator display provide information about the variation of both the direction and the degree of orientation with both height and time. A quantitative analysis procedure used in a detailed study of one particularly interesting series of observations is described. It was found that collective orientation occurred frequently, and that it sometimes became very well-developed. The direction of orientation remained approximately constant for long periods, but did not appear to be consistently related to any obvious directional cue; changes in direction were observed on occasions, however, and one such change was clearly associated with a change in the direction of the wind. The degree of collective orientation was a rather more variable quantity than the direction, and increases in degree were sometimes associated with increases in the number of locusts arriving at the observation site.

Studies in southern England on aphids in cereals and adjacent wasteland included observations on the survival of aphid-specific predators (Coccinel-lidae and Syrphidae) and the more polyphagous Chrysoperla carnea (Steph.), with particular reference to their parasites. Counts were made of all the predator stages found on samples of shoots in each plot and, in wheat only, collected with a vacuum sampler. All stages of predators seen were collected and reared in the laboratory to estimate mortality and parasitism rates. Overwintering survival outdoors of Coccinella septempunctata L. was studied in partly sheltered and exposed netting cages over dense ground cover. At least 90% of predator eggs hatched in the laboratory, and no parasites were reared from them or from larvae. In cereals, there were significantly fewer larvae than eggs of Coccinellidae, probably because of cannibalism, whereas eggs and larvae of Chrysoperla carnea and Syrphidae (mainly Episyrphus balteatus Deg.) occurred in similar numbers. Unlike Coccinellidae, however, there were fewer cocoons of C. carnea and syrphid pupae on the shoots than expected. Since larval mortality was apparently small, it is suggested that many larvae pupate in the soil. Two parasite species emerged from coccinellid pupae and one from the adults, compared with two species from C. carnea cocoons and nine species from syrphid pupae. Parasitism rates were usually small (25%). More individuals of Coccinella septempunctata survived overwinter in partly sheltered than in exposed cages.

Experiments were undertaken in July and August 1982 in Northern Ireland to examine the effects of some factors which could influence the number of craneflies caught by water traps. Tipula paludosa Mg. and T. oleracea L. were caught, but the latter only in small numbers. Catches of males of T. paludosa, but not of females, decreased as the height of the trap walls increased. All catches were larger in traps of greater diameter. A significant colour preference was found for males of T. paludosa, in the order green > red > yellow > white > blue > black. Increasing the number of traps per unit area increased the mean catch per trap. It is concluded that the attraction of traps for craneflies, if any, is only slight and that the insects may descend randomly over traps so that greater numbers are caught in wide, low-walled traps. Catch is possibly greatest in green traps because of an inability of craneflies to distinguish them from grass.

The biology of Bubas bison (L.) was studied in southern France. It was active from September to the end of May. Adult emergence lasted from September to January; 8 % of the female population was parous and laying eggs in September, and 100% were parous from February to the end of June. Females exhibited extraovariolar egg resorption, which may have been a response to adverse conditions. Eggs laid in October, November, February and March hatched synchronously in May. Adults resulting from eggs laid in March emerged in early September. The rate of oviposition varied from 0–03 egg/day in January to 0·5 in March. Females stopped laying eggs for three weeks in January. The structure of the nests formed from buried dung brood-masses was studied. Each brood-mass contained two eggs, one at each pole. About 12 brood-masses were formed under each dung pad in October 1981. The mean length of each mass was 96 mm and the dry weight 10–5 g. The mean number of masses in a nest was 24, with a mean number of 4–9 nests under each dung pad. The dry weight of dung buried under a pad in October 1981 was 1239 g, 66–6%, of the mean dry weight of an experimental dung pad. B. bison has the potential for recycling large amounts of dung in climatic areas of Australia equivalent to southern France.

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.

The numbers of mealybugs and other Homoptera on 96 cocoa trees in Ghana were assessed by examining four branches from each tree. The trees were then felled and examined in detail. Ten species of mealybugs, eight other coccoids, an aphid and a psyllid were recorded. Ninety–five of the trees were infested with mealybugs, 66, 90 and 69 trees, respectively, with Planococcoides njalensis (Laing), Planococcus citri (Risso) and Phenacoccus hargreavesi (Laing). Stictococcus sjostedti Ckll., a species of Gascardia near G. zonata (Newst.) and Mesohomotoma tessmanni (Aulm.) were found on 70, 68 and 48 trees, respectively. The remaining 14 species were found on fewer than 48 trees. All species other than Pseudococcus calceolariae (Mask.) and Ferrisia virgata Ckll.) were most prevalent in the canopy. In the field, mealybug densities recorded on shoots underestimated true levels by an average of 95%. Branches were as effective as whole trees for detecting mealybugs, but less effective for other Homoptera. Branches were suitable sample units for estimating population densities of mealybugs, stictococcids and psyllids. All species of mealybug other than F. virgata infested vegetative buds. An average of 21.7% of buds on the youngest shoots were infested. Samples of buds can be used for detecting mealybug infestations.

The assumption that by minimising contact with pyrethroids, satisfactory control of Musca domestica L. could be retained without eliciting resistance was tested on a pig farm in southern England where permethrin had failed through rapid development of resistance. Flies were satisfactorily controlled in enclosed buildings for 12 months by space spraying bioresmethrin (2 mg a.i./m3) at approximately fortnightly intervals when numbers reached an arbitrary nuisance level. Throughout this period, bioassays revealed no increase in tolerance of pyrethroids, although selection experiments in the laboratory confirmed the strong pyrethroid-resistance potential of the fly population. Thus effective control can be retained in spite of strong resistance potential when non-persistent insecticides are used intermittently. The results are discussed in the light of a published theoretical study of the influence of pesticide persistence on the evolution of resistance.