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.

Members of the family Cimicidae (Heteroptera: Cimicomorpha) are temporary bloodsuckers on birds and bats as primary hosts and humans as secondary hosts. Acanthocrios furnarii (2n=12=10+XY, male) and Psitticimex uritui (2n=31=28+X1X2Y, male) are two monotypic genera of the subfamily Haematosiphoninae, which have achiasmatic male meiosis of collochore type. Here, we examined chromatin organization and constitution of cimicid holokinetic chromosomes by determining the amount, composition and distribution of constitutive heterochromatin, and number and location of nucleolus organizer regions (NORs) in both species. Results showed that these two bloodsucker bugs possess high heterochromatin content and have an achiasmatic male meiosis, in which three regions can be differentiated in each autosomal bivalent: (i) terminal heterochromatic regions in repulsion; (ii) a central region, where the homologous chromosomes are located parallel but without contact between them; and (iii) small areas within the central region, where collochores are detected. Acanthocrios furnarii presented a single NOR on an autosomal pair, whereas P. uritui presented two NORs, one on an autosomal pair and the other on a sex chromosome. All NORs were found to be associated with CMA3 bright bands, indicating that the whole rDNA repeating unit is rich in G+C base pairs. Based on the variations in the diploid autosomal number, the presence of simple and multiple sex chromosome systems, and the number and location of 18S rDNA loci in the two Cimicidae species studied, we might infer that rDNA clusters and genome are highly dynamic among the representatives of this family.

Experiments were conducted in a cotton field in north-western New South Wales to determine the effect of pheromone trap design and placement on the catch of Helicoverpa punctigera (Wallengren) and H. armigera (Hübner) adults in paired traps. A cone trap design was found to give consistently larger catches of moths than two funnel trap designs. Furthermore, lower efficiency of catch of H. punctigera tended to bias relative catches in the funnel traps towards H. armigera. In comparison to the ratios of the two species in egg samples from the field, the cone trap did not show much bias to either species of moth. Traps located 40 m inside a cotton field showed larger catches and reduced variation compared with egg species ratios than traps placed at the edge of the field. Wind speed and direction and insecticide application also affected the catch in the traps. The catch data tended to become unreliable after the end of February, possibly due to changes in crop attractiveness for oviposition. It was found that the less numerous moth species at a given time still tended to be over-represented in pheromone traps in comparison to the ratios in egg counts. A linear time trend was introduced to compensate for the bias. The use of the traps shows promise in determining the relative abundance of the two species for use in resistance management strategies and other purposes.

From January to July 1938, experiments with Anopheles maculipennis race atroparvus, Van Thiel, were undertaken to discover whether humidity and the age at which the females fed influenced their longevity. It was found that they lived longer at higher than at lower humidities; that most of the females which fed did so in the first three days; that those which fed on the second day after emergence lived longer than those which fed at other ages; and that the feeding period was slightly extended in the later experiments, though only a small proportion lived long enough to take their first blood meals on the fourth and fifth days.

Rather more than 50 per cent. of each batch of newly emerged adults were females.

A large proportion of the deaths of unfed males and females occurred during the first three days, most of them on the second day; this mortality decreased in successive experiments.

Culex fatigans, Wied., behaved similarly.

Continuous trapping of winged Aphids was carried out with Moericke trays and a suction trap for two years at a site at 6,850 ft. above sea level in Kenya, and with Moericke trays, for four months only, at a site at 1,200 ft. in southern Tanganyika.

The trap data show a marked seasonal periodicity of flight (three-quarters of the annual catch in two months) at the Kenya site. The large catch is a reflection of a large increase in population following the rains. A similar relation between size of catch and the period of the rains is indicated by the data from Tanganyika.

Successive hourly catches with a suction trap show no distinct diurnal double peak of aerial density such as occurs in Europe.

The present paper is the outcome of a visit to Turkey at the invitation of the Turkish Government in the summer of 1931 to study the local locust problem and to advise on the general policy of locust control.

To determine the extent to which the distribution of ovipositing Heliothis armiger (Hb.) might be ‘clumpy’ rather than random, the numbers of eggs on cotton throughout the 10 000 km2 Sudan Gezira were subjected to analyses of variance. It was found that at any time there was less variability within than between areas, highly significantly less for units of 600–700 km2. Within all areas, the numbers of eggs varied very significantly with time and many-fold increases in numbers of eggs occurred simultaneously over thousands of square kilometres. In every three-day period, there were two or more significantly different levels of infestation, each extending over areas ranging from a few hundred to several thousand square kilometres; the boundaries of such areas changed continuously, and no consistent differences or patterns were found. These findings suggest that redistribution of mobile populations of moths takes place over large distances. At all times there were areas with egg numbers below those considered economically serious; this has been utilised in new control strategy and tactics which have been effectively implemented experimentally. Larval spraying appeared also to reduce oviposition for at least three days and could in part account for some, but certainly not all, of the differences between areas.

A key is given for the separation of a group of allied species of Eulophidae comprising Elachertus nigritulus (Zett.), E. geniculatus (Eatz.), E. olivaceus (Thoms.), E. scobiciae Erdős, and a species here described as E. pallidus sp. n. Biological data for each species are given. E. nigritulus and E. geniculatus have previously been regarded as synonymous; the latter parasitises Laspeyresia strobilella (L.), a pest of conifers, whereas E. nigritulus, and also E. pallidus, attacks Lepidoptera associated with fruit trees.

Culex pipiens s.l. is one of the primary vectors of West Nile Virus in the USA and Continental Europe. The seasonal abundance and eco-behavioural characteristics of the typical form, Cx. pipiens pipiens, make it a key putative vector in Britain. Surveillance of Culex larvae and adults is essential to detect any changes to spatial and seasonal activity or morphological traits that may increase the risk of disease transmission. Here we report the use of the modified Reiter gravid box trap, which is commonly used in the USA but scarcely used in the UK, to assess its suitability as a tool for British female Culex mosquito surveillance. Trapping was carried out at 110 sites in urban and rural gardens in Berkshire in May, July and September 2013. We tested if reproductively active adult female Culex are more abundant in urban than rural gardens and if wing characteristic traits and egg raft size are influenced by location and seasonal variations. Gravid traps were highly selective for Culex mosquitoes, on average catching significantly more per trap in urban gardens (32.4 ± 6.2) than rural gardens (19.3 ± 4.0) and more in July than in May or September. The majority of females were caught alive in a good condition. Wing lengths were measured as an indicator of size. Females flying in September were significantly smaller than females in May or July. Further non-significant differences in morphology and fecundity between urban and rural populations were found that should be explored further across the seasons.

The damage caused by the Cotton Jassid to the Egyptian-type cottons in the Gezira and White Nile areas of the Sudan is very considerable. Realisation of this fact has been greatly aided by chemical control of the pest in small-scale experiments, followed by large-scale work with tractor-drawn sprayers and with helicopters fitted with spraying equipment. This paper deals primarily with examination of available records pertaining to the cotton crops in the four seasons from 1946/47 to 1949/50, preceded firstly by an introduction which emphasises the importance of yield records in the appraisal and interpretation of losses from pests, and secondly by an account of certain aspects of the pest in the Gezira Scheme.

Large-scale spraying to control the pest started in the Gezira in the crop season 1945/46; yield increases from about 1,250 feddans (acres) sprayed with 0·1 per cent. DDT emulsion were very satisfactory. In succeeding seasons increasing areas were sprayed; in 1947/48 spraying was extended to the cotton farms along the White Nile between Khartoum and Kosti; in 1949/50 the total area sprayed in the Sudan was over 150,000 feddans. Material and also methods and dates of application varied considerably.

Anastepha ludens (Diptera: Tephritidae) is a highly polyphagous fruit fly that is able to develop in a wide range of hosts. Understanding the limits of this pest's host range could provide valuable information for pest management and plant breeding for pest resistance. Previous studies have shown that guavas (Psidium guajava (Myrtaceae) L.), are not attacked under natural conditions by A. ludens. To understand this phenomenon, guavas were exposed to natural infestation by A. ludens and to other fruit fly species that infest guavas in nature (Anastrepha striata Schiner, Anastepha fraterculus (Wiedemann), Anastepha obliqua (Macquart)). Once the susceptible phenological stage of guavas was determined, fruit infestation levels were compared between A. ludens and A. striata. Choice and non-choice tests were performed under field-cage conditions. Under field conditions, guavas were susceptible to A. striata and A. fraterculus attack all the way from when fruit was undeveloped to when fruit began to ripen. No infestation by A. ludens was recorded under natural conditions. Similar results were obtained when forced exposures were performed, indicating that unripe guavas were preferred by A. striata over ripe fruit, and that infestation rates were higher at early fruit maturity stages. Under forced oviposition conditions, A. ludens larvae were unable to develop in unripe guavas but did so in fully ripe fruit. However, A. ludens fitness parameters were dramatically affected, exhibiting reduced survival and reduced pupal weight compared to conspecifics that developed in a natural host, grapefruit. We confirm that P. guajava should not be treated as a natural host of this pestiferous species, and suggest that both behavioral aspects and the fact that larvae are unable to adequately develop in this fruit, indeed represent clear limits to A. ludens's broad host range.

Observations were carried out, chiefly between March and June 1962, in an area centred on Bolgatanga in northern Ghana in the hope of finding out how Simulium damnosum Theo. survives the ‘ dry season ’. The term ‘ dry season ’ is used here for the unfavourable season when running water in the rivers is evidently absent or is insufficient or perhaps unsuitable for the development of any, or more than a negligible number of, individuals of S. damnosum from egg to adult. The incidence of this season varies from year to year and does not correspond to the season without rain. It may usefully be divided into reduced-flow, main dry, pre-flow and early-flow periods.

Search was made for larvae and pupae before rivers began to flow, without result. Observations were made on the numbers of flies biting, general appearance, wing measurement, antennal colour, mid-gut, fat-body, ovaries and parasites, chiefly at the beginning of the rainy season, in an attempt to trace the history of the species during the preceding weeks. Flies appeared before the rivers began to flow but did not give evidence of having lived for months. On the days when two rivers began to flow, considerable numbers of flies were caught, and most of those dissected proved to be parous and had evidently been in the adult stage for some days. A nematode parasite of the Malpighian tubes was found only in April, with one exception up to 10th May, and was probably associated with the dry-season biology of the host.

The possibility that S. damnosum migrates from permanent foci, or exists near its breeding places in one or more stages at different times, is discussed. Migration from afar seems very unlikely. The species survives in the adult stage for at least part of the ‘ dry season ’, but more information is required to complete the picture.

Survival is apparently not dependent to a significant extent on perennial breeding locally, and there is, therefore, no easy solution to the problem of control. Operational research might show if there is a carry-over generation and if control after the rains and towards the end of the breeding season would prevent it from developing. There is some indication that the risk of infection with Onchocerca tends to be low at the end of the ‘ dry season ’, which is a time when control would be particularly difficult.

The results of observations on wing measurements, antennal colour and the peritrophic membrane are given in an Appendix.

This paper is mainly an account of the known distribution of the 36 species and eight varieties of Phlebotominae found in the Sudan. Their economic importance is briefly discussed.

Liquid sugar baits are well accepted by the Argentine ant Linepithema humile and are suitable for the chemical control of this invasive species. We evaluated how sugar concentrations affect the foraging behavior of L. humile individuals. We quantified feeding variables for individual foragers (ingested load, feeding time and solution intake rate) when feeding on sucrose solutions of different concentrations, as well as post-feeding interactions with nestmates. Solutions of intermediate sucrose concentrations (10–30%) were the most consumed and had the highest intake rates, whereas solutions of high sucrose concentrations (60 and 70%) resulted in extended feeding times, low intake rates and ants having smaller crop loads. In terms of post-feeding interactions, individuals fed solutions of intermediate sucrose concentrations (20%) had the highest probability of conducting trophallaxis and the smallest latency to drop exposure (i.e. lowest time delay). Trophallaxis duration increased with increasing sucrose concentrations. Behavioral motor displays, including contacts with head jerking and walking with a gaster waggle, were lowest for individuals that ingested the more dilute sucrose solution (5%). These behaviors have been previously suggested to act as a communication channel for the activation and/or recruitment of nestmates. We show here that sucrose concentration affects feeding dynamics and modulates decision making related to individual behavior and social interactions of foragers. Our results indicate that intermediate sucrose concentrations (ca. 20%), appear to be most appropriate for toxic baits because they promote rapid foraging cycles, a high crop load per individual, and a high degree of stimulation for recruitment.

Species that belong to the Aphidius eadyi group have been used as biocontrol agents against Acyrthosiphon pisum worldwide. However, despite their extensive use, there are still gaps in our knowledge about their taxonomy and distribution. In this study, we employed an integrative taxonomic approach by combining genetic analyses (mtDNA COI barcoding) with standard morphological analyses and geometric morphometrics of forewing shape. We identified three species within the A. eadyi species group, viz., A. smithi, A. eadyi and A. banksae. Genetic separation of all three species was confirmed, with mean genetic distances between species ranging from 5 to 7.4%. The following morphological characters were determined as the most important for separating species of the A. eadyi group: number and shape of costulae on the anterolateral part of the petiole, shape of the central areola on the propodeum, and shape and venation of the forewings. The differences in wing shape of all three species were statistically significant, but with some overlapping. We identified A. banksae as a widely distributed pea aphid parasitoid, whose known range covers most of the western Palaearctic (from the UK to Israel). Aphidius banksae is diagnosed and redescribed.

It may be stated that the summation of microscopical evidence of harmful effect upon the exposed rats and rabbits as a result of their 28 days' exposure to continuous DDT aerosol as described was nil.

A study of the immature stages of the Anthomyiid flies, Delia cilicrura, D. trichodactyla, Erioischia brassicae, E. floralis and Pegohylemyia fugax, associated with injury to cruciferous crops, has shown that the several species can be distinguished. The egg stage can be identified by the sculpturing of the chorion, except in the case of the closely related species E. brassicae and E. floralis where the sculpturing is similar but there is a considerable difference in size.

The larvae can be distinguished by differences in the shape and character of the head and in its relation to the prothorax, and in the form of the mouth-parts in the three instars. The number of finger-like processes of the anterior spiracles and the number and arrangement of the tubercles of the eighth abdominal segment also contribute to the identification of the larvae.

A serious sugarcane pest, Dasylepida ishigakiensis, remains in the soil during most of its life cycle except for a short period for mating. Mating disruption by an artificial release of the sex pheromone (R)-2-butanol (R2B), therefore, may be a feasible method to control this pest. We examined the effects of artificial release of R2B and its related compounds, (S)-2-butanol (S2B) and the racemic 2-butanol (rac-2B), on the mating success of this beetle both in the laboratory and in the field. In flight tunnel experiments, almost all males orientated towards a R2B-releasing source and 40% of them landed on the source. When the atmosphere was permeated with R2B, the frequency of males landing on the model was significantly reduced. Both rac-2B and S2B were less effective, but substantial reduction in landing success by males was achieved at higher rac-2B concentrations. R2B released from polyethylene dispensers in sugarcane plots greatly reduced not only the proportion of females mated with males but also the number of males caught by R2B-baited traps, indicating that male mate-searching behaviour was strongly affected by the released R2B. Similar inhibitory effects on male behaviour were also observed when tube- or rope-type dispensers released high rac-2B concentrations in the field. These results indicate that it would be highly possible to control D. ishigakiensis through the disruption of the sexual communication by releasing either synthetic R2B or rac-2B.

The screwworm, Cochliomyia hominivorax (Coquerel), is one of the most important pests of livestock in the Western Hemisphere. During early immature stages it is morphologically very similar (first instars are virtually indistinguishable) to the secondary screwworm, C. macellaria (Fabricius). Here, the utility of the random amplified polymorphic DNA–polymerase chain reaction (RAPD–PCR) was explored as a technique for developing molecular genetic markers for these two species. Of the 120 arbitrary primers screened, 21 primers produced markers that were further investigated. Seven of the 21 primers produced clear and reproducible markers that were tested with DNA of five individuals from four populations of each species; five of these primers showed 12 RAPD markers that differentiated the species in all populations. Analyses of data from these seven primers also suggested that intraspecific polymorphisms exist that could be useful in distinguishing populations of screwworms. Some population genetic tools, such as genetic distance, cluster analysis and bootstrapping, were used to statistically explore these polymorphisms. The resulting statistics showed 100% support for the ability of RAPD–PCR to discriminate between the two species. Bootstrapping with data from one of the genetic distance calculations produced a tree with all individual screwworms in the correct populations, indicating that RAPD–PCR has promise for displaying intraspecific genetic variation that could be used in establishing the general geographic origin of screwworm samples.

Precipitin tests were performed on 238 blood-smears made from Culicine mosquitos collected from natural resting places at three sites, in the area surrounding a village, in uninhabited forest, and at an uninhabited rock outcrop in savannah vegetation in Northern Nigeria. In calculating the percentages of blood-meals that were positive for the various animals, the following criteria were applied: all negative results were subtracted from the totals tested; in calculating mammalian, but not avian or reptilian, percentages, all records that referred to “mammal, weak smear” were subtracted; “unidentified mammal” was included in the calculations. Results showed that Culex pipiens fatigans Wied. (taken only in the area surrounding the village) had fed mainly on man (45%) and birds (36%), and while Aedes vittatus (Big.) (taken only at the rock outcrop) fed to some extent on both man (14%) and birds (18%), the majority of blood-meals (54%) had been obtained from the porcupine (Histrix cristata). It is thought that these feeds on man from individuals of Ae. vittatus taken at an uninhabited site may have been obtained from villagers using a road about 150 yd. from the outcrop. Ae. luteocephalus (Newst.) (the majority of which were taken in forest) also fed to some extent on porcupine (11%) and birds (16%), but the principal host appeared to be Bovids (74%). It was established for the first time that Uranotaenia mashonaensis Theo. (the majority of which were taken in forest) bites man (29%); mammals other than man and birds accounted for 29 and 24 per cent., respectively. Half of the blood-smear samples obtained from females of this species did not react to any antisera, and were classified as negative.