Long distance migration by adults of Chortoicetes terminifera (Wlk.) in Australia was shown to be associated with the accumulation of fat-body lipid. Lipid was accumulated if the plant growth index was 0·3 or more within a week of the final moult; when the plant growth index was less than 0·3, there was little fat accumulation. Locusts with large amounts of fat-body lipid migrated on nights with warm strong winds, while those with little persisted.

Egg parasitoids attacking economically important pod-sucking Hemiptera on cowpea were collected in Nigeria and Tanzania. The three coreid hosts, Anoplocnemis curvipes (F.), Clavigralla tomentosicollis Stål and C. elongata Sign., and the two alydid hosts, Mirperus jaculus (Thnb.) and Riptortus dentipes (F.), form a pest complex that attacks grain legumes across Africa. Parasitoids attacking eggs of C. tomentosicollis were monitored on farmers' fields at a locality in northern Nigeria. Parasitism rose from low initial levels to maxima of 62% in 1978 and 51% in 1979. This mortality did not keep host populations below the economic injury level. The egg parasitoid complex of C. tomentosicollis was dominated by the scelionid Gryon gnidus (Nixon), while the encyrtids Ooencyrtus patriciae Subba Rao and O. kuvanae (How.) parasitised a large proportion of host eggs at times. Small numbers of Gryon fulviventris (J. C. Crawford) and the eupelmids Anas tatus spp. were reared. Observations on the biology and behaviour of O. patriciae are presented. This species occurred in both Tanzania and Nigeria and attacked all hosts studied. Rearings of all these parasitoids and also another species of Gryon, a species of Baeus and two species of Telenomus from eggs of the five species of Hemiptera are reported.

Effective control of Ephestia cautella (Wlk.) by Blattisocius tarsalis (Berl.) has occasionally been observed in warehouses. It has been postulated that this control is negated by fumigation under sheets, because of differential effects on the moth and its predator, and removal of alternative prey. The biology of B. tarsalis was studied at 27°C and 73% RH. On eggs of E. cautella, development took 5·9 days and there was 7% mortality; on eggs of Tribolium oastaneum (Hbst.), development took 7·4 days and there was 48% mortality. When offered a choice of eggs of the two pest species, the mites very rarely preyed on those of T. castaneum. The number of E. cautella eggs consumed (after correction for partial consumption) was 3·8 (total) by nymphs, 2·4/day by ovipositing females, 1·5/day by non-ovipositing females, and 0·8/day by males. The sex ratio (female: male) was 2·5:1. Adult life-span averaged about 55 days (maximum 153 days), and the oviposition period lasted about 20 days. Females laid up to 5 eggs/day at peak oviposition. The potential rate of increase of B. tarsalis on E. cautella eggs was very high, far exceeding that of its prey. These data confirm previous postulates concerning the role of B. tarsalis in natural control of E. cautella, and support the hypothesis that fumigation reduces predator-effectiveness. Modification of control regimes might allow greater natural control by the mite and reduce the increasing pest status of the moth.

Females of the Pakistan strain of Apanteles flavipes (Cam.) (which originates from Japan and is maintained on larvae of Chilo partellus (Swinh.) reared on maize) were readily attracted to maize stems but not to sugar-cane stems in the laboratory. Ovipositor probing occurred in the presence of unwashed host larvae, particularly of C. partellus and/or frass from host larvae fed on maize. Ovipositor probing did not occur in the presence of dried frass, dried frass that had been remoistened with water or frass from C. partellus fed on a diet of gram (Cicer arietinum) flour. The Pakistan strain of A. flavipes is morphologically identical to a strain of A. flavipes imported from India into Florida and established on Diatraea saccharalis (F.) fed on a soyabean flour-wheat germ diet. Reciprocal crosses between the two strains (Pakistan and USA) and between the F1, adults produced both male and female progeny. Nevertheless, behavioural differences between the strains were found in laboratory tests in that the USA strain responded more strongly to larvae of Acigona steniellus (Hmps.) fed on sugar-cane, was more attracted to sugar-cane stalks than to maize stalks and was not encapsulated by D. saccharalis larvae, whereas at least one-fifth of the Pakistan strain larvae were encapsulated. The existence of different strains of Apanteles flavipes adapted to different graminaceous crops suggests that parasite plant preference as well as host preference and suitability must be considered during attempts to introduce exotic parasites. It is recommended that A. flavipes strains adapted to sugar-cane be introduced into Pakistan for establishment on stem-borers of sugar“-cane.

Psila rosae (F.) overwinters in Britain in both the larval and pupal stages. Overwintering pupae formed in October and November at soil temperatures of between 10 and 16°C entered diapause. A period of similar temperature in the laboratory during the prepupal stage also caused pupae to enter diapause. Overwintering larvae continued to feed and gain weight; they pupated in early spring at soil temperatures of 2–8°C but did not enter diapause. The sensitivity to diapause-inducing conditions decreased between November and March, associated with changes in developmental temperatures and pupal weight. The differential effects of temperature on larval, pupal and diapause development together serve to synchronise adult emergence from the overwintering population. The mechanisms which allow overwintering by a variable proportion of larvae and pupae also provide the opportunity for the development of a third generation of adult flies in October and November.

The internal reproductive system of adult males of Spodoptera littoralis (Boisd.) is described, and changes in colour of a secretion in the ductus ejaculatorius simplex with age and mated status are noted. Virgin males 0–7 days old and mated males 0–7 days after mating were killed and the colour of the secretion in the simplex compared with colour chips in the Munsell book of color (1929–1942). The results showed that the simplex of newly emerged males was colourless or pale yellow, but after two days an orange pigmented secretion had begun to accumulate in 61·3% of males examined. By four days this pigment had darkened to deep red in 96·4% of virgin males. On mating, a portion of this secretion was incorporated into the spermatophore while the rest was passed into the bursa copulatrix of the female, leaving the simplex of newly mated males colourless. There was. however, a gradual re-accumulation of the pigmented secretion after mating through yellow, orange and finally to deep red. This accumulation of the red pigment was slightly slower in the mated males than in virgins, and three days after mating only 29·6% of the males had a red simplex compared with 78·8% of three-day-old virgin males. The potential use of these changes in colour to determine the mated status of field-caught males is discussed.

The numbers of adults of Hydrotaea irritans (Fall.) caught in Manitoba traps in north-eastern England varied greatly between successive 30-min periods. Weather variables accounted for 49·4% of this variation, but only wind speed and sunshine showed significant simple correlations with fly catch. Using principal component analysis of weather data, three principal components accounted for 67·3% of the variation in catch. The two components most highly correlated with catch were composed mainly of wind speed, sunshine, shade temperature and radiant temperature. These two principal components were used as covariates in an analysis of the effects of a heated target and carbon dioxide on trap effectiveness. Heating the target to blood temperature increased the catch of females 1·8-fold but had only a slight effect on the catch of males. The presence of CO2 increased the female catch nearly fivefold and the male catch more than fourfold. There was no interaction between the two stimuli of heat and CO2. A separate experiment showed no significant difference in catch between CO2-baited traps using spheres 0·6 or 0·3 m in diameter as the target.

A new easily-produced cheap compound for use as a bait matrix is described. The light-weight matrix of polyurethane is prepared from dense precursors into which suitable attractants and toxicants can be incorporated for the pest species in question. It has a high bait effectiveness/weight ratio, and so is very suitable for aerial application as large economically viable payloads can be achieved. When tested both in the laboratory and in the field on a small scale against the leaf-cutting ant Acromyrmex octospinosus (Reich), the bait was highly acceptable to the ants. Some formulations, especially those coated with mirex gave excellent control of ants in the field in Trinidad, killing all occupants of nests within four days of baiting. The bait exhibited good weathering properties, was resistant to fungus attack, and allowed the slow release of pheromones. It was much cheaper than the citrus pulp baits normally used in Trinidad.

A gelechiid moth whose larvae attack the flower buds and young leaves of sapodilla (Achras zapota), known also as chicle gum, chiko or naseberry, in northern India and Pakistan is described and named Anarsia achrasella sp.n. Wing pattern, labial palpal and genitalic features of both sexes of the adult are figured, and the species is differentiated from the closely related Afrotropical A. pinnata Meyr.

Analysis of catches of Chrysoperla carnea (Steph.) in a light-trap and a suction trap at Rothamsted, southern England, showed that the light-trap catch varied as predicted from a model proposed to describe the functioning of a light-trap: catch = constant × , where W = trap illumination and I = background illumination. After adjustment to allow for changes in illumination during the flight period of C. carnea, the light-trap catch was very similar to the suction-trap catch. For C. carnea, a light-trap provides as unbiased a sample as a suction trap, but because of variation in trap effectiveness with variation in illumination, light-trap catches obscure changes in activity and abundance. Although similar studies are desirable to confirm this for other species, it is suggested that in light-trap studies catches should be adjusted to allow for changes in illumination during flight or trapping periods.

Seasonal variation in the circadian periodicity of mating behaviour in Chilo suppressalis (Wlk.) was investigated. In the field, mating was initiated at dusk in June, but not until after dark in August. The times of females calling and of male catches in a pheromone trap were later in August than in June. The seasonal variation in time of male catches coincided approximately with that of mating, suggesting that latter may be attributable in part to seasonal changes in the response of males to the sex pheromone. Also, it is likely that these variations are affected by environmental factors, especially temperature.

Aedes ledgeri Huang, A. soleatus Edw. and A. calceatus Edw. of the group of A. aegypti (L.) of the subgenus Stegomyia collected on the coast of Kenya are distinguished on the strength of ecological and genetic (isozyme) data. The preferred oviposition sites of A. ledgeri and A. soleatus were tree holes above ground level, whereas A. calceatus favoured abandoned gastropod shells. A. ledgeri was most abundant in ecotonal habitats and A. soleatus in undisturbed forest At least two diagnostic enzyme loci separated each of the three species pairs.

A soft scale found infesting mango in Israel is described from the female as Coccus elatensis sp. n. It is morphologically related to C. gymnospori (Green), which is redescribed.

A laboratory evaluation of growth, food consumption and food utilisation by larvae of Spodoptera littoralis (Boisd.) was made from the beginning of the fifth instar to the prepupal stage on cabbage, cotton, kenaf and Congo jute (Urena lobata). Growth, measured by daily larval fresh weight, was highest on cabbage and similar on kenaf, Urena and cotton. Development was fastest on cabbage and slowest on cotton and Urena. Larvae underwent an extra moult on the latter two food-plants. Weight gain was highest on cabbage, followed by cotton, Urena and kenaf, in that order. Total food consumption was highest on cotton and lowest on kenaf and Urena. Cabbage was most efficiently digested, followed by kenaf, cotton and Urena, in that order. Digestive efficiency on all four plants declined with larval age. The efficiency of conversion of ingested food to body material was highest on cabbage and lowest on cotton and kenaf. Digested portions of Urena were most efficiently converted to body substance while digested portions of cabbage and kenaf were most inefficiently converted to body material. It is concluded that S. littoralis is better adapted to cabbage than any of the other three plants and that increasing cultivation of cabbage in Ghana is likely to enhance the pest status of the insect.

Epigaeic ants were sampled by pitfall trapping in three South African citrus orchards supporting low levels of Aonidiella aurantii(Mask.). All three were similar except that chemical control of the scale was in progress in one, biological control in the second, while the third was in transition from chemical to biological control. Within-orchard variation was statistically zero at the chemical and biological control sites, both of which had constant species abundances and rank-abundance sequences throughout. Within the transition site, rank-abundance sequences were constant but species abundancies varied. Despite the statistical constancy of rank, within-orchard samples at the transition and chemical control sites varied in their dominant ants. The biological control site was dominated throughout by Pheidole megacephala(F.). Individuals of the dominant species made up between 59 and 69% of the total, and as the dominant species varied, this high figure suggested strong interspecific competition. Log-normal models were fitted to the site rank-abundance plots. The interquartile index, Q, was higher when based on an underlying log-series model (α) than on a log-normal one; it was about 2·0, which is low compared with most other studies. The total numbers of individuals and species of ants were higher in the biological control than chemical control orchard. Diversity, as measured by α or Q log-normalwas lowest in the chemical control site, medium in the biological controlone, and highest in the transition site. Between-site variation showedvariation in general ant abundance. As with the within-orchard results, those between orchards were relatively constant. Ant management in relation to community structure is critically appraised on the basis of limiting factors (especially abundance of honeydew as food for potentially dominant ants) and rank-abundance sequences.

The taxonomic status of the western Palaearctic crop plant pests Trioza nigricornis Först., T. tremblayi Wagn. and T. brassicae Vasil'ev is discussed, and a related species T. trigonica sp. n. (of which the probable host-plant is carrot) is described. Each species is fully illustrated, and a key to them is provided.

Laboratory and field experiments were carried out in Australia to determine the effect of arthropods in cattle dung on the survival of the eggs and larvae of Musca vetustissima Wlk. They were tested in the numbers in which they came to dung pads near Canberra, during the 1978–79 and 1979–80 seasons. Laboratory tests indicated that the mite Macrocheles glaber (Müll.), the hydrophilid Cercyon sp. and the histerid Saprinus sp. were all very effective predators. The native dung beetles Onthophagus granulatus Boh. and O. australis Guér. exerted only a marginal controlling effect; and the staphylinid and aphodiine beetles were found to be largely ineffective. The control exerted by the total field fauna when brought into the laboratory was considerable when one or more of the three species of effective predators was present. In the field trials, the control of M. vetustissima was further enhanced by the adverse influence of weather.

A computer model of a tsetse population was developed to determine whether insecticide resistance could evolve as a result of current tsetse control programmes. Chemical analyses were also carried out which showed that Glossina morsitans morsitans Westw. can metabolise DDT to DDE, indicating a potential for insecticide resistance in this species. The model showed that a completely isolated tsetse population stands little chance of surviving attacks with insecticides repeated at short intervals. However, when sufficient time is allowed between applications, such a population may survive and evolution of resistance take place. Given a small amount of immigration, the evolution of resistance is retarded, but population extinction is prevented. The degree of resistance developed by a population also depends on the dominance relationship of a resistant gene with its wild-type allele and on the reproductive fitness of the mutant. It is suggested that control strategies are adopted which would minimise the risk of insecticide resistance becoming a problem in tsetse and that susceptibility studies are carried out both before spraying operations and on any residual population post-spraying.

Glossina pallidipes Aust. was captured from a moving vehicle and in Moloo traps at three-week intervals from October 1975 to December 1976 in the Kibwezi Forest, Kenya. The percentage of teneral flies captured was about twice as high in the vehicle samples as in the traps. Samples in the traps were mainly of older flies, especially parous females. The numbers of G. pallidipes collected in the traps during 20 two-day periods were correlated with those collected from the vehicle. The vehicle-catch levels were less variable than those in the traps. By both methods the highest numbers were collected in September (cold season) and the lowest in November-December (short rains). Attraction to the vehicle followed a bimodal diel pattern at all seasons, with a higher morning (09.30–10.00 h) than afternoon (17.30–18.00 h) peak, and a midday depression at 13.30–14.00 h; the afternoon peak was much reduced in parous females. At all seasons, only one distinct peak (at 15.00–17.00 h) and very low catches at night were exhibited by flies attracted to the traps.