Reproduction of Varroa jacobsoni Oudemans has been extensively studied in colonies of the mite's recently acquired host, Apis mellifera Linnaeus. However, data on reproduction in colonies of its original host, A. cerana Fabricius, are still fragmentary. In order to compare reproductive success in naturally infested brood cells of A. cerana and A. mellifera, freshly capped worker and drone cells (0–5 h after capping) were marked and opened 9 days later. When one or more foundress Varroa mites were found, the number and stage of the offspring were recorded. In colonies of A. cerana, V. jacobsoni reproduced almost exclusively in drone cells. Surprisingly, however, these drone cells proved to be better suited for reproduction than drone (and worker) cells of A. mellifera. Firstly, in drone cells of A. cerana, 97–100% of the mites produced daughters and 98–99% of these mites also produced a son. In drone and worker cells of A. mellifera only 70–80% produced daughters and only 74–86% of these mites produced a son. Secondly, if a mite produced daughters, she produced more daughters in drone cells of A. cerana than in drone cells of A. mellifera: 4.5–4.6 vs 2.9–3.7 daughters per mite, respectively. Finally, infestation by two foundress females negatively affected reproduction per mite in drone cells of A. mellifera, but not in drone cells of A. cerana. Thus, V. jacobsoni seems to be better adapted to A. cerana than to A. mellifera, although population growth of mites in A. mellifera colonies is higher due to the exploitation of worker cells besides drone cells.

An account is presented of the distribution and amounts of moonlight in latitudes near the equator. This includes a Table on the amount of moonlight for each hour of the night throughout a standard lunar cycle, applicable to any locality between 10°N and 10°S, and a Table of standard groups of moon phase which can be used at any locality irrespective of latitude. The construction of these Tables is described in detail and their use briefly discussed. A method is described which enables light-trap catch records to be arranged for analysis directly against moon phase.

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), which is often controlled chemically, is a major citrus pest in Spain; however, alternative biological control strategies such as those based on the conservation of polyphagous predators should be developed. The wolf spider, Pardosa cribata Simon, is an abundant predator found in citrus orchards in eastern Spain. In this study, we have evaluated polymerase chain reaction (PCR)-based techniques as a means of detecting C. capitata DNA remains in P. cribata specimens. To do so, two pairs of C. capitata species-specific primers were designed and tested. Primer specificity was tested on species closely related to C. capitata and with other pests and natural enemies present in citrus orchards. Medfly DNA was detectable in 100% of P. cribata from 0 to 12 h post ingestion for both primer pairs, decreasing to 37% at 96 h after prey ingestion for one pair of primers. DNA detectability half-lives were of 78.25 h and 78.08 h for each pair of primers but no statistical differences were found between them. Pardosa cribata specimens were field-collected daily after sterile C. capitata pupae had been deployed in the citrus orchard. Afterwards, the wolf spiders were analyzed and DNA remains of C. capitata were detected in 5% of them, with a peak of 15% coinciding with maximum C. capitata emergence. This study is the first to reveal the potential use of DNA markers to track medfly predation by P. cribata in citrus orchards and provides a new tool to estimate the potential role of this spider in biological-control conservation programs.

Field populations of Lucilia cuprina (Wied.) in New South Wales were sampled for periods of 3 h on numerous occasions between 1975 and 1982 using West Australian blowfly traps. Ambient temperature, wind speed, relative humidity and solar radiation explained 77·4% of the within-day deviance of the catches. Temperature alone accounted for 74·9% of this deviance, indicating that the other variables, although significant, did not greatly affect trap catches. As air temperatures increased, log catch rates increased linearly up to 26°C and then remained constant up to 35°C. Wind speeds above 25 m/s caused a linear decline in log catch rates. Log catch rates increased linearly as solar radiation increased and decreased linearly as relative humidity increased. Changes in catch rates with time of day were explained almost entirely by the four weather variables, i.e. there was no evidence that intrinsic behavioural changes with time of day affected catch rates. The combined effects of the four weather variables accounted for 47·1 % of the between-day variation in trap catches. Trap catches that have been standardised, i.e. adjusted to a ‘ standard’ set of weather conditions, provide relative measures of population size which differ from absolute measures by a constant (unknown) scaling factor.

The distribution and biology of two related species of mosquito, Mansonia (Mansonioides) africana (Theo.) and M. (M.) uniformis (Theo.), have been compared. M. uniformis is found from China to Africa, whereas M. africana is restricted to the continent of Africa. The two species do not interbreed although mating, but no insemination, is possible in the laboratory. Strains of M. uniformis from Africa, Ceylon and Malaya are interfertile, but crosses between the African and the other strains, especially, showed a reduction in fertility of the eggs produced and thus some evidence of speciation.

The two species show the same adult behaviour at mating, feeding (both in the field and in the laboratory) and during oviposition. Both species are stenogamous and mate readily in small cages. The first blood-meal is taken approximately 24 hours after emergence and immediately after each oviposition, 3–5 days after the previous blood-meal. M. uniformis is more active directly after the blood-meal.

The effects of cultivation and treatments with DDT and BHC on soil Collembola and Acarina were, investigated. Cultivation resulted initially in a drastic reduction of the micro-arthropod population and in the fallow plots this reduction persisted. Re-seeding resulted in rapid recolonisation by Collembola, but the populations of Oribatei and Mesostigmata remained at a low level over a period of 17 months after sowing. Treatment with BHC caused a heavy reduction of most micro-arthropoda. DDT caused reductions of mites, particularly Mesostigmata, but there was a marked increase of Collembola in the plots so treated. Significant increases of Collembola and significant reductions of predacious Mesostigmata were also noted in the comparison of plots treated with a DDT plus BHC mixture with those receiving BHC alone. The increase of Collembola was thus associated with a reduction of predatory pressure. In most cases, the effects of the treatments that included BHC were apparent 17 months later, but a temporary recovery of near-surface dwelling Collembola occurred in the BHC-treated plots in February 1952. Of the groups and species significantly affected by insecticide treatments in October 1951, only in one case did the data of October 1952 produce significant evidence of recolonisation. This recovery was noted in the DDT-treated population of Punctoribates punctum (Koch).

Eighteen parasitoids were recorded from the African stem borer, Busseola fusca (Fuller), on maize and grain sorghum, in Delmas and Cedara, South Africa. In Delmas, larval parasitism on both crops fluctuated below 20% with occasional peaks of 40–60%. In Cedara, larval parasitoids were active throughout the season with peaks of 75% and 60% parasitism during January and March-April, respectively on the ratoon crop, and 20% in May on the crop. Pupal parasitism peaked in Cedara at 100% during February-March, and at 80% during November, when parasitoids attacked pupae that formed after B. fusca larvae had emerged from diapause and pupated. In Delmas activity by pupal parasitoids was negligible. The egg parasitoids, Telenomus busseolae Gahan (Hymenoptera: Scelionidae) and Trichogrammatoidea lutea Girault (Hymenoptera: Trichogrammatidae), were rare. The larval parasitoid, Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae), was active throughout the season and was by far the most abundant, emerging from about 90% of parasitized larvae. Its cocoons were often attacked by Aphanogmus fijiensis (Ferrière) (Hymenoptera: Ceraphronidae). Second in abundance among the larval parasitoids was Bracon sesamiae Cameron (Braconidae) whose cocoons were attacked in turn by Eurytoma braconidis Ferrière (Hymenoptera: Eurytomidae). Eurytoma braconidis was reared also from cocoons of Euvipio sp. and Aleiodes sp. (both Braconidae). All other larval parasitoids were rare. Procerochasmias nigromaculatus (Cameron) (Hymenoptera: Ichneumonidae) was the most abundant pupal parasitoid. Trichogrammatoidea lutea, Glyptapanteles maculitarsis (Cameron) (Braconidae) and Odontepyris transvaalensis (De Buysson) (Hymenoptera: Bethylidae) have not been recorded before from B. fusca. Some considerations and proposals for introductions of parasitoids into South Africa against B. fusca are discussed.

Movements of individual fourth instar Coccinella septempunctata L. larvae on pot-grown broad bean plants in England were recorded continually to assess plant recognition and the effects of prey capture. Prey capture was also studied in a 25X25 cm artificial arena. Approximately 80% of the total distance moved by larvae on plants was along leaf edges and mid-veins. Typical search speeds were 0−38−0−51 cm s−1. An average of only 3−2% of larval search time on plants was spent on leaf laminae on which movement was considerably slower, about 0−15 cm s−1. Discovery of Acyrthosiphon pisum (Harris) nymphs on plants induced intensive re-searching of the general area of discovery for periods of up to 12 min whereas in the arena the intensive search following prey capture lasted only up to 72 s and was much more localised. Examination of larval search times on plants revealed that 64% and 36% of maximum search times were recorded for the first and for the second or third searches, respectively, in a sequence of searches of the same plant. Only after prey capture was a fourth or subsequent search the longest. Plants previously searched unsuccessfully were recognised by detection of a chemical marker, specific for each individual, secreted via the anal disc during searching. Since C. septempunctata larvae are unable to detect aphids by sight or smell, recognition of areas previously searched unsuccessfully minimises wasteful energy expenditure.

The experimental manipulation of separate, but originally identical, populations of Ixodes ricinus (L.) by applying three conventional tick control measures in different enclosures on naturally infested moorland in Wales allowed the elements of the tick-host interaction to be analysed quantitatively and the effectiveness of the control methods to be compared. From the relationship between the sheep stocking density and the numbers of questing ticks picked up by fortnightly blanket-dragging in each enclosure, the death rate of ticks during their activity season and the rate of contact between sheep and ticks were calculated. From this, it was possible to investigate the effect of different stocking densities on the feeding success of ticks. A major factor determining the much lower contact rate for larvae than for nymphs was the different spatial distribution of questing ticks, clumped for larvae and random for nymphs. The non-random use by sheep of the three different vegetation zones in the paddock resulted in the highest contact rate between sheep and ticks in the pasture area, but tick survival was apparently highest in the bog area. Combining these factors resulted in the prediction that the bracken area was the least favourable habitat for ticks. In the two enclosures where the sheep were not treated with acaricide the mean tick loads on the sheep were similar, but the lower overall use of the pasture by the sheep in the low stocking density enclosure (2/ha) resulted in slightly lower tick loads there compared with those in the high stocking density enclosure (4/ha). The numbers of ticks counted in the second year showed that pasture spelling was the most effective control method, acaricide treatment was less effective, and the benefits of halving the stocking density were marginal. The implications of these results for control strategies are discussed.

Stem borers are the most important maize pests in the humid forest zone of Cameroon. Field trials were conducted in the long and short rainy seasons of 2002 and 2003 to assess the level of damage and yield reductions caused by stem borers in monocropped maize and in maize intercropped with non-host plants such as cassava, cowpea and soybean. The intercrops were planted in two spatial arrangements, i.e. alternating hills or alternating rows. All intercrops and the maize monocrop were grown with and without insecticide treatment for assessment of maize yield loss due to borer attacks. The land-use efficiency of each mixed cropping system was evaluated by comparing it with the monocrop. The temporal fluctuation of larval infestations followed the same pattern in all cropping systems, but at the early stage of plant growth, larval densities were 21.3–48.1% higher in the monocrops than in intercrops, and they tended to be higher in alternating rows than alternating hills arrangements. At harvest, however, pest densities did not significantly vary between treatments. Maize monocrops had 3.0–8.8 times more stems tunnelled and 1.3–3.1 times more cob damage than intercrops. Each percentage increase in stem tunnelling lowered maize grain yield by 1.10 and 1.84 g per plant, respectively, during the long and short rainy season in 2002, and by 5.39 and 1.41 g per plant, respectively, in 2003. Maize yield losses due to stem borer were 1.8–3.0 times higher in monocrops than in intercrops. Intercrops had generally a higher land-use efficiency than monocrops, as indicated by land-equivalent-ratios and area-time-equivalent-ratios of >1.0. Land-use efficiency was similar in both spatial arrangements. At current price levels, the net production of mixed cropping systems was economically superior to controlling stem borers with insecticide in monocropped maize. The maize–cassava intercrop yielded the highest land equivalent ratios and the highest replacement value of the intercrop. At medium intensity cropping this system is thus recommended for land-constrained poor farmers who do not use external inputs such as fertilizer and insecticides.

The life cycle, within-field distribution, crop damage and impact of natural enemies of the potato tuber moth, Phthorimaea operculella (Zeller) were investigated in two potato cropping systems. The two systems differed in soil type (sandy vs. loess) which in turn affected the choice of cultivars, irrigation programme, insecticide application method (ground vs. aerial), and planting and harvest times. From mid-April to the end of May, almost twice as many moths were caught in pheromone traps in sandy than in loess fields. Highest infestation of tubers was found before harvest, and infestation was greater in loess than in sandy fields. Larval densities in foliage and tubers were significantly higher at the margins of the fields than in the centre. A significant positive correlation was found between adult catch and larval infestation on foliage in sandy fields but not in loess. Tuber infestation in sand was positively correlated with foliage infestation. No such correlation was detected in loess. Five parasitic wasps emerged from P. operculella larvae collected from commercial fields and volunteer plants: Diadegma pulchripes (Kokujev) and Temelucha decorata, (Gravenhorst) (Ichneumonidae) and Bracon gelechiae Ashmead and two other unidentified Braconidae. The most abundant predators at the field site were Coccinella septempunctata Linnaeus (Coccinellidae), Chrysoperla carneaStephens (Chrysopidae), Orius albidipennis (Reuter) (Anthocoridae) and four ant species (Formicidae). Parasitism rate reached 40% and predation was estimated at 79%. Results are discussed with regard to the development of an integrated pest management programme for this important pest.

Insect seed predators of 24 dipterocarp species (including the genera of Dipterocarpus, Dryobalanops and Shorea) and five species belonging to the Moraceae, Myrtaceae, Celastraceae and Sapotaceae were investigated. In a tropical lowland dipterocarp forest in Sarawak, Malaysia, these trees produced seeds irregularly but intensely during general flowering and seeding events in 1996 and/or 1998. Dipterocarp seeds were preyed on by 51 insect species (11 families), which were roughly classified into three taxonomic groups: smaller moths (Tortricidae, Pyralidae, Crambidae, Immidae, Sesiidae and Cosmopterigidae), scolytids (Scolytidae) and weevils (Curculionidae, Apionidae, Anthribidae, and Attelabidae). Although the host-specificity of invertebrate seed predators has been assumed to be high in tropical forests, it was found that the diet ranges of some insect predators were relatively wide and overlapped one another. Most seed predators that were collected in both study years changed their diets between general flowering and seeding events. The results of cluster analyses, based on the number of adults of each predator species that emerged from 100 seeds of each tree species, suggested that the dominant species was not consistent, alternating between the two years.

The stage of egg formation and density of follicular relics enable Lucilia cuprina (Wied.) females to be sorted into 16 ovarian stages, covering the period from emergence to the beginning of the fourth ovarian cycle. The correspondence between the actual age of a fly and its stage of ovarian development was determined at constant temperatures. Where developmental delays were absent, “reproductive age” gave reliable estimates of actual age under both constant and fluctuating temperature regimes. In the field protein shortages and lack of oviposition sites may prolong the time required to complete each ovarian cycle, and flies will be older than their ovaries would indicate. In practice the ovarian stages described provide estimates of minimum age for L. cuprina females.

In a revised classification of the Tropiduchidae, which includes a number of species injurious to crops, the family is divided into 15 tribes, of which six (Cixiopsini, Eporini, Isporisini, Neommatissini, Remosini and Turneriolini) are proposed as new, two (Eutropistini and Tangiini) are given new status and seven are redefined. New subtribes (Clardeina, Neotangiina and Duriina) are erected in Eporini, Tangiini and Eutropistini, respectively, and Kazeruniina is given new status in the last. The genera Chiotasa and Habrotasa are transferred to Achilidae, Dolia, Hiracia, Karna, Parahiracia, Siebererella and Gastrinia to Issidae, and Kruegeria to Ricaniidae, and Dichoneura is brought into Tropiduchidae from Delphacidae. Biruga chariclo Fennah is transferred to Athestia to form a new combination, and Tambinia theivora sp. n. is described from material that included examples collected on tea.

The existence of a genetic component in the determination of flight capacity suggested by the results of previous experiments on the effects of environmental factors on flight performance in Spodoptera exempta (Walker) was confirmed by successful selection for and against the capacity for prolonged flight. The results of selection experiments were consistent with those expected when a polygenic character is subjected to directional selection. Heritability estimates for flight duration were 0·4 for overall heritability (mean offspring on mid parent regression) and 0·5–0·9 for single sex offspring on female and male parent regressions, demonstrating that flight capacity has a substantial additive genetic component. Although there can be no doubt that genetic factors play a major role in the control of migration in S. exempta, it is not yet clear whether flight capacity is a continuously varying character or whether discontinuous variation in the form of a genetically controlled flight polymorphism is involved. It is suggested that the life-history strategy of S. exempta is adapted to maximise dispersal in the rains when a massive extension of favourable habitat occurs, and to maintain populations in those habitats which remain favourable in the dry season. The present evidence suggests that this strategy is achieved by cyclic selection of genetically determined variability in potential flight capacity.

1. The behaviour of Anopheles labranchiae atroparvus, Culex pipiens molestus and Aëdes aegypti has been studied before and during oviposition.

2. Anopheles and Culex when ready to lay make repeated descents to the ground and fly about with a skimming-hopping movement, while Aëdes flies about generally, at all heights.

3. On encountering water Anopheles breaks into a hovering flight, laying its eggs during this “oviposition dance” or while settled on the water. Culex stops “dead” on the water and lays its eggs settled there, as does Aëdes but with some fidgeting about. After encountering water mosquitoes may leave it again, but fly about the floor more steadily and persistently than before.

4. Among the factors which stimulate mosquitoes after they have arrived directly over a water surface, contact with the surface is essential for actual oviposition by Culex and Aëdes, and almost so for Anopheles. Good pre-ovipository responses may be induced by water vapour alone and by the reflection from the surface, although how this latter stimulus acts is not clear. A dark appearance, especially if the surroundings are relatively light, facilitates these responses.

5. Direct attraction of the mosquitoes over the short range available in a cage was only induced by a contrastingly dark appearance, but Anopheles and Culex are aided in water finding by diurnal changes, correlated with light and activity changes, in the sense of their geotactic response.

Laboratory and field observations have been made on the biology of Wheat Bulb Fly in the years 1943–45. The eggs hatch in late January and early February. Severe frosts delay hatching but do not kill the eggs. In a laboratory experiment a high proportion of eggs buried 18 inches below the soil surface, hatched, and the larvae infested plants. Field observations showed that proportions of the eggs also survive prolonged flooding.

The development and habits of the larvae are recorded. It was confirmed that oats are not a suitable host and though a very small number of these plants were infested the larvae did not survive. Occasionally two larvae infest the same shoot and when this happens one larva dies. The larvae leave the plants in April or early May and pupate in the soil. The pupal stage lasts six to seven weeks.

The adults emerge, males first, in June. Copulation occurs about three weeks after emergence and at this time dense aggregations of flies occur. Usually males predominate in these and in certain circumstances all the flies are males. The flies disperse gradually from the field in which they emerged and the females start laying eggs in suitable areas about a month after emergence. In Yorkshire egg laying occurred in July and early August and lasted about a month. Even within the limited area and time of these observations variations up to three weeks were noted in different places and seasons. Lateness was associated with heavy soils.

Much of the first part of this paper is in the nature of a continuation of the work previously published by the author. (Bull. Ent. Res., xxi, 1930, pp. 201–256). For this reason only a brief description can be given of the locality, vegetation, game, and fly-round methods ; those desiring a fuller knowledge on these subjects are referred to the above-mentioned paper. Again, a certain amount of repetition has been unavoidable. Some results obtained from only one year's observation have now been confirmed during a period of four and a-half years, and so have been given again. It is felt that this repetition is justifiable as the results in question are of special value, in that they are derived from four and a-half years continuous observation upon the same fly-belt, the method employed being constant throughout the whole period.

The writer is in charge of Kikori Entomological Station, which he opened in March 1928 ; nine months later he was joined by his assistant Captain V. A. C. Findlay.

The native village of Kikori is situated at the foot of the Masai escarpment, which bounds the Masai Steppe on the west. Kikori lies about 45 miles north of Kondoa-Irangi (the principal centre of the district), its approximate bearings being Latitude 4° 21′ S. and Longitude 33° 19′E. ; its elevation is 4,158 feet above sea-level.

The bionomics of sandflies (Phlebotomus: Psychodidae) have been studied mainly in relation to the diseases they transmit. Comparatively little experimental work has yet been undertaken on the physiology of Phlebotomus in the laboratory. In the present paper experiments are described on the thermal limits of Phlebotomus, on the influence of temperature and humidity on the length of life of adult sandflies and on the loss of water in larvae and pupae. The problem of loss of water in sandflies is of particular interest, since adjustment to a varying humidity under natural conditions appears to be an important factor in the transmission of diseases by these insects.

For the study of sandflies in the laboratory an ample supply of insects raised under uniform conditions is required. In a previous publication (1934) a breeding method has been described which provides any desired number of sandflies. If overcrowding of the breeding pots is prevented the flies are relatively uniform.

The species used in the experiments was Phlebotomus papatasii, the common sandfly of the Mediterranean, which is the most suitable species for laboratory work; it is comparatively easy to breed and to handle and feeds readily in captivity. The sandflies used in the experiments were bred from females caught in October in Jerusalem. The pots containing the larvae were wrapped in moist cottonwool and survived the transport to London without any damage. The work was commenced, and parts of it completed, in the Department of Entomology, London School of Hygiene and Tropical Medicine, where I held the Avebury Studentship. It is a pleasure to acknowledge the help received from Professor P. A. Buxton and the valuable collaboration of Mr. J. D. Gillett. The work was completed in Jerusalem.

In a study of aphids and their parasites, hyperparasites and predators in a field of cereals at Rothamsted Experimental Station in 1970–71, samples were taken by counting specimens in 0·3-m lengths of row and by means of a suction trap set 12·2 m above ground and 0·5 km away from the field. Migrant aphids (Metopolophium dirhodum (Wlk.) and Macrosiphum avenae (F.)) and Braconid parasites (Aphidius spp., Ephedrus plagiator (Nees) and Praon volucre (Hal.)) were caught from April–May to August–September, with most from mid-June to August, whereas hyperparasites (Phaenoglyphis sp., Lygocerus aphidivorus Kieff., Asaphes vulgaris Wlk., Coruna clavata Wlk. and Alloxysta sp.) occurred for more of the year. Of the six parasite species attacking aphids on cereals in 1970–71, three Aphidius spp. were more common than E. plagiator and Praon volucre. Parasitism was higher and aphids were fewer in 1971 than in 1970. In the field, more than 80% of the mummies were of old nymphs; parasitism of live old nymphs and apterae was similar, larger than for alatae, and larger for Metopolophium dirhodum than for Macrosiphum avenae. Hyperparasitism by five species affected parasitism, especially in 1970. Migrant Coccinellids were trapped at the start and end of aphid infestations on cereals, Syrphids mainly in July and August, and other predators for longer. The commonest predators were Coccinella septempunctata L. and Propylea quatuordecimpunctata L. in 1970 and Syrphus balteatus (Deg.) in 1971; the others were scarce. July populations of aphids were primarily reduced by the Syrphids.