Earlier types of suction sampling apparatus, driven by electric or petrol motors, are briefly reviewed and their disadvantages for work in remote areas indicated. To overcome these a cheap, simple, hand-operated model has been developed and the construction of this is described. However, unlike some of the motorised models, it does not extract all the fauna from the area sampled.

The overwintering stages of the carrot fly (Psila rosae (Fabricius)) were sampled at Wellesbourne, Warwickshire, during the winters of 1987, 1988, 1989 and 1990. Between 20% and 55% of the insects overwintered as pupae in diapause. The remaining insects stayed in the larval stage during the winter period and gave rise to non-diapausing pupae in the early spring. In May, adults emerged earlier, and over a shorter period, from insects that overwintered as larvae than those that overwintered as pupae. Diapause was most intense during late December and early January. In the laboratory, diapause was completed at temperatures of 5°C and above but was not completed at 0°C. When the overwintering stages were sampled in early February and maintained at constant temperatures in the laboratory, the overwintering pupae required from 114 days at 9°C to 44 days at 21.5°C to give rise to adults. In contrast, the overwintering larvae required only 91 days (9°C) and 27 days (21.5°C), respectively. Populations of overwintering P. rosae collected from Warwickshire and Norfolk had similar requirements for spring emergence but diapause pupae collected in Lancashire emerged over a longer period of time than those collected in Warwickshire. Comparisons with published data indicated that North American and European pupae had different requirements for the completion of diapause. Accumulation of weather data for a P. rosae forecast should start when temperatures are low and any date in early February would be suitable.

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.

Field sampling of populations of Sitobion avenae (Fabricius) on spring wheat in the north-western USA from 1988 to 1991 produced a data set consisting of 47 estimates of mean aphid density (m; number of aphids per tiller), variance (s2) and the proportion of tillers (PT) with no more than T = 0, 1, 2, …10, 15, 20, and 25 aphids, respectively; defined as the tally threshold. The average sampling error level of the four-year data set was 0.196 (SE= 0.013). The empirical relationship between m and PT was developed for each T value using the parameters from the linear regression of ln(m) on ln[-ln(Pϒ)] and was satisfactory when T = 2, 3, 4, and 5 (as evidenced by the high r2 values and relatively small mean squared errors from the regression analyses relating to the T values). In comparing the variances estimated from different formulae for predicting m from PT, the variance of Binns & Bostanian (1990b) was found to be more conservative and reliable in estimating the prediction variance. This variance was used in the development of binomial sampling plans for each T and in the determination of associated sampling precision denoted by the half-width of the confidence interval (d). Binomial sample sizes based on the T values of 2–5 were found to be associated with relatively small d values that may actually be reached and thus, are recommended for use in monitoring aphid populations for control decision making. However, at population densities below one aphid per tiller, binomial sampling was found to be feasible only when counts were based on empty tillers (T = 0).

Males of Diparopsis castanea Hmps. were caught in a water trap baited with sex pheromone sited 2·0 m above ground level in a cotton field in the Lower Shire Valley, Malawi. Analysis of catches for 21 nights between 8.iii.75 and 3.vi.75 showed that optimal catches of males occurred at wind speeds of 1·0−2·5 m s−1. Wind speeds in excess of 3–4 m s−1 depressed activity. Regression analysis revealed an optimal relative humidity for flight of 60−70%. Inclusion of humidity in a multiple regression analysis with wind speed and temperature failed to improve significantly the relationship with catch provided by a model that considered wind speed and temperature only. No simple relationship existed between temperature and moth abundance, and wind speed clearly exerted the greatest independent effect on catch. Male Diparopsis nevertheless exhibited a temperature-related pheromone responsiveness, with peak catches occurring earlier in scotophase during periods of cool weather. Analysis of data gathered during the 1973 and 1974 seasons indicated a slight, but significant, positive correlation between night rainfall and moth catch. However, none of the various independent and joint relationships established between moth catch and climatic factors could be reliably used for forcasting moth abundance.

Observations additional to those made by Dunn (1927) of Culicine mosquitos breeding in “ test ” water containers about a Compound in Southern Nigeria, near Lagos, are here reported for a period of the year (June to December) not covered in Dunn's study. Only the optimum type of container mentioned in Dunn's report (bamboo joints containing water and mango leaves) was employed, and these were placed in the same ten representative environmental situations. The numerical rank of infesting species differed significantly in the two studies only in the case of Culex decens, which dropped from third to last place, and of Aëdes africanus, which rose from tenth to sixth place. The total numbers of infestations in the former study were greater, but this is explainable on the basis of one or several variables, i.e., seasonal differences, elapse of time between studies, or less probably the fact that there were four containers instead of one at each station. The number of infestations at any one station has little relation to the number of resultant adults; there is a wide variation in these numbers.

An analysis of the occurrence of A. aegypti in containers and a discussion of certain bionomical information together with relative weather conditions are included. Brief data are also presented of the incidence of species at three additional stations, one in a centre of dense population (Lagos), one in a suburb (Ebute Metta), and the third isolated in dense “ bush.”

Bruchus dentipes Baudi was found to have four larval instars, and the sex ratio was very close to 1:1. Both sexes fed on pollen and nectar of faba beans (Vicia faba) for seven days before and throughout the oviposition period of the females, which was about 33 (range 26–40) days. The beginning and peak of oviposition were influenced by the phenology of the crop, particularly flowering and pod-setting dates, but also temperature. Females laid an average of 123 (range 28–310) eggs, and the end of the adult life in the field came in May when the pods had matured. In different years, peak oviposition occurred on different dates in April when the pods were still all green. During the quiescence period in the winter, females obtained from wetted seeds were fed with different diets in the laboratory, but only those supplied with faba bean flowers laid eggs. No major adult mortality occurred in seeds harvested in May and stored until the end of March of the following year, after which mortality rose steeply till all adults had died by early June. Therefore, storing seeds and delaying their planting till the following year will ensure 100% adult mortality. As the seeds remain viable, such storage is one method for reducing infestation in the field. Mortality of larvae in the stored seeds was from cannibalism when two larvae met at the same tunnel (10%), from the mite Pyemotes tritici (Lagrèze-Fossat & Montagné) (11%), from the braconid larval parasite Triaspis thoracicus (Curtis) (2%) and from unknown reasons (5%).

Having received from the Imperial Bureau of Entomology more material of the family LONCHAEIDAE, I am in a position to give the following additional notes to my previous paper* on the Ethiopian species.

A dieldrin emulsion spray containing 3 per cent, dieldrin (w/v) was applied once to the putative resting places of Glossina morsitans Westw. throughout a comparatively isolated 17-sq.-mile fly-belt in the Kabiganda Valley in southwestern Uganda between October 1957 and September 1958. Concentration areas of the fly consisted of one or more tall trees with associated understorey and thicket. The lower sides of the branches of an average of 6·75 such trees per acre were treated at a rate of about one-fifth of a pound of dieldrin per acre and at a cost of about £250 per sq. mile.

Chemical analysis showed a deposit of approximately 0·8g. dieldrin per sq. metre on the surface sprayed, and although 90 per cent, of this had disappeared from the surface after about four months, it is thought that the application remains effective for this period.

A very great reduction in the tsetse population was achieved. Small numbers of flies continued to be caught, but it was thought possible that these were being brought in from neighbouring valleys by buffalo, and, hence, that insecticidal application of this sort, if carried out over a wide enough area, might eradicate a tsetse population.

Adults of Hydrotaea irritans (Fall.) in south-western Scotland were caught in a Manitoba trap and a black suction trap baited with carbon dioxide. Trapped flies were dissected to investigate their reproductive condition, their blood feeding activity and whether they were newly emerged. Trapping of the first gravid females in August was accompanied by a sharp decline in adult activity. The proportions of females in the various ovarian categories suggested that there is a preliminary phase before host-seeking begins, attraction to animals during most of the cycle and a behavioural change at the end. Females with eggs at stages I, II and III accounted for 94% of all females caught; the only females with blood in the gut were in these categories. Some males also were obviously blood-fed. There was a single mating period lasting five weeks. Inseminated females were first trapped in the third week of July, when the numbers of males started to decline, and within five weeks all females trapped were found to have been inseminated. After this, no more males were caught. Only females with eggs in stages later than stage II of the first ovarian cycle were inseminated. H. irritans was univoltine, with two but not three complete ovarian cycles during the summer. There was no difference in feeding or reproductive development between flies from the two traps.

Coccus celatus De Lotto is now established on coffee in Papua New Guinea where it is causing some concern. As a result of studying extensive collections of this species from the Sudan and Papua New Guinea, it is now possible to synonymise the name C. consimilis De Lotto with C. celatus. An account of the distribution and host range is given.

Human experience in the past has often been crystallized into homely saws, of which the one that states that “ Prevention is better than cure ” should be regarded as one of the foundation stones of all work in economic entomology. We see this put into practice in such routine measures as the destruction of mosquito and fly larvae, ploughing fields in the dry weather to destroy grasshopper egg-masses, the destruction of weeds and stubble, the collection of egg-masses, caterpillars and hoppers, the enforced removal of cotton-plants after harvest, legislation against the introduction of pests into new countries, and similar measures which are so familiar that they need not be enlarged on here. Such measures are directed to and, if applied consistently, are largely effective in keeping within bounds insects which, if not thus checked, normally attain to destructive numbers, and by “ normally ” I mean that on the average they occur in such numbers every year, or for a series of years. There are, of course, fluctuations, due to natural causes, in the pest-status of many insects, which may be insignificant in normal years and occasionally rank as bad pests, or vice versa ; of such causes we know as yet very little, beyond the pious ascription of them to the effects of parasitic control or climate. But, after eliminating these fluctuations, we still often find our expectations upset by outbreaks for which it is very difficult to invoke any adequate explanation other than that they are the effect of a large influx into the area affected of the insect concerned. Such a theory may appear far-fetched at first sight, especially as it is very difficult of proof in most cases, but we find in India an accumulation of cases for which such an explanation seems the only one possible.

Bactrocera dorsalis (Hendel) and Ceratitis capitata (Wiedemann) are highly polyphagous fruit fly species and important pests of commercial fruit in regions of the world where they are present. In South Africa, B. dorsalis is now established in the north and northeastern parts of the country. B. dorsalis is currently absent in other parts of the country including the Western Cape Province which is an important area for the production of deciduous fruit. C. capitata is widespread in South Africa and is the dominant pest of deciduous fruit. The demographic parameters of B. dorsalis and C. capitata on four deciduous fruit types Prunus persica (L.) Batsch, Prunus domestica L., Malus domestica Borkh. and Pyrus communis L. were studied to aid in predicting the potential population establishment and growth of B. dorsalis in a deciduous fruit growing environment. All deciduous fruit types tested were suitable for population persistence of both B. dorsalis and C. capitata. Development was fastest and survival highest on nectarine for both species. B. dorsalis adults generally lived longer than those of C. capitata, irrespective of the fruit types that they developed from. B. dorsalis had a higher net reproductive rate (Ro) on all deciduous fruit tested compared to C. capitata. However, the intrinsic rate of population increase was estimated to be higher for C. capitata than for B. dorsalis on all fruit types tested primarily due to C. capitata's faster generation time. Provided abiotic conditions are optimal, B. dorsalis would be able to establish and grow in deciduous fruit growing areas.

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.

Two new species of Eulophidae, which are potential biological control agents of economically important pests, are described from China. Aprostocetus prolixussp. n. (Tetrastichinae) is an egg-parasitoid of Apriona germarii (Hope) (Coleoptera: Cerambycidae), and Hyssopus grossorissp. n. (Eulophinae) is a larval parasitoid of Paranthrene tabaniformis (Rottenburg) (Lepidoptera: Sesiidae). The species Elachertus pallidus Askew is transferred to Hyssopus, comb. n.

The sugar-cane scale, Aulacaspis tegalensis, Zehnt., has been known to exist in Mauritius since the year 1899, when de Charmoy recorded it for the first time in the Island.

The species was described by Zehntner in 1898 from Java on sugar-cane, since when little has been recorded of its geographical distribution. In 1921, Ferris recorded it from Formosa. In 1938, D. d'Emmerez de Charmoy, jr., called the attention of the planters of Reunion to the damage caused by this scale on sugarcane, and the author had suspected its presence there many years previously. In Java it was considered of minor importance by Zehntner in 1897. In 1911 Van Deventer drew attention to the damage it caused in Java, and in 1915 van der Goot recorded a serious infestation in the experimental cane fields of the Java Experimental Station. Apart from these records, it has not been reported from other sugar-cane growing countries.

Eggs, larvae and pupae of Spodoptera littoralis (Boisd.) were exposed to five non-freezing constant temperatures (13°, 10°, 7°, 4° and 1°C). The period of exposure required to kill eggs and larvae, and to affect pupae seriously, was determined at each temperature. Distinction was made between dead pupae and pupae which were not killed but developed into deformed adults incapable of mating or laying fertile eggs. Probit line analysis was applied to the mortality results and response lines were plotted for all developmental stages at each constant temperature. Observed 100% mortality and computed LD 99 estimates showed that at all temperatures, except 1°C, resistance to cold was minimal at the egg stage, increased in maturing larvae and was at a maximum in the pupal stage, so that the order of the LD 99 values was: pupae (dead)>larvae>eggs. At 1°C the order was: pupae (dead)>30-day-old larvae>eggs>15-day-old and 1-day-old larvae. The LD 99 (days) value decreased with decreasing temperature for all larval stages and for pupae; and for eggs it was greater at 1°C than at 4° and 7°C.

The following descriptions are based on material collected by Mr. H. E. Box in the Gold Coast, during his work on insect pests of the cocoa plantations, and submitted to me for identification by the Imperial Institute of Entomology. Owing to war-time difficulties in obtaining various scientific journals, it is not always possible to make certain that a species is undescribed, so that although Mr. Box has collected several others which may be new, they have not been described here for that reason. The species now dealt with, however, are of particular interest either from the point of view of new distribution or from remarkable structure or striking colouration. Type specimens are preserved in the British Museum.

Cordia macrostachya (Jacq.) R. & S. (Boraginaceae) is a serious pest in Mauritius, to which island it was accidentally introduced from the West Indies. During investigations of the possibility of the biological control of this weed, Kirby (1944 unpublished report, “Insects of Cordia in Trinidad”) and Donald (1945 unpublished dissertation) worked out the biology of the Galerucid, Schematiza cordiae, Barber (J. Wash. Acad. Sci. 37, p. 243, 1947), a defoliating species that gave promise of meriting consideration for introduction into Mauritius.