Dieldrin, aldrin and γBHC in kerosene were applied topically to adults of Cosmopolites sordidus (Germ.) collected from banana plantations with no history of insecticide application and from plantations that had been treated regularly with dieldrin for many years. Adults from the latter source were highly resistant to dieldrin and aldrin, while resistance to γBHC was lower; those from the former source were susceptible and the results could be used as base line data. Females collected in spring from two untreated plantations showed LD50 values for dieldrin varying by a factor of 1·5, while females collected in the spring were 1·7 times more susceptible than those collected in the autumn from the same plantation. A discriminating dose of 1 μl of 1·0% dieldrin per weevil is considered suitable for detecting resistant individuals.

Diclidophlebia eastopi Vondráček and D. harrisoni Osisanya are pests of the timber tree Triplochiton scleroxylon in Nigeria. The egg and five nymphal instars are described and illustrated. Under laboratory conditions the life-cycle (egg-egg) of D. eastopi was completed in 18½ days, and mated fed females had a life span of 15 days. The sex ratio in the field was 1:1. Nymphs feed near the veins of mature leaves, causing premature leaf fall; adults feed on leaves of any age and cause no symptoms. Fecundity averaged 502 eggs, with a daily oviposition rate of 38; most eggs are laid in batches along the veins of mature leaves. The life-cycle of D. harrisoni was 16 days; mated and fed females lived 10 days. The feeding of firstinstar nymphs near the margins of young leaves causes leaf tunnels to form, inside which the nymphs complete their development; adults feed only from young leaves. In the field the female:male ratio was 2:3. Fecundity averaged 131, with a daily oviposition rate of 31. Fertility improved with multiple matings. The eggs are laid singly, partially embedded in the epidermis, and only on young leaves.

Techniques used in the radar detection and identification of individual flying insects are outlined, and laboratory and field measurements of the radar cross section of the desert locust, Schistocerca gregaria (Forsk.), are presented. The cross section was strongly aspect-dependent, and had an average value of approximately 1 cm2 at a radar wavelength of 3·2 cm. An example is given of the periodic fluctuation in radar cross section (the radar ‘signature’) produced by locusts in free flight, and the spectral contents of the signatures obtained from 35 laboratory-bred free-flying locusts are described. The fundamental components of the signatures, presumed to be at the wing beat frequency, were closely grouped about 23 Hz. It is suggested that the feasibility of using radar signatures as a means of insect identification will largely depend on the degree to which the species of interest are characterised by specific wing beat frequencies. Estimates of locust flying speed and heading deduced from photographs of locust and balloon radar tracks produced a mean value of 5·3 m s-1. Undetected small-scale flight manoeuvres may introduce negative errors in the estimation of flying speed. It is concluded that radar will provide unique observational facilities for the entomologist but that the limitations introduced by the problem of target recognition have yet to be defined.

In this ecological survey conducted mainly in western Tanzania between 1962 and 1969, six species of Earias were found, including two undescribed species and E. cupreoviridis (Wlk.), which is restricted to Sida spp.; E. biplaga (Wlk.) and E. insulana (Boisd.) were the only species found on cotton and were virtually restricted to Malvales. Differences in the incidence of Malvales and the Earias larvae feeding on them were noted on a research farm and on surrounding local farms as being due to different farming practices and soil types. E. biplaga was the dominant species on cotton for most of each year and its major alternative host was Waltheria indica; E. insulana was relatively more common on cotton in the dry season and was particularly common on Abutilon spp. Populations of E. biplaga increased on W. indica early in the rainy season, then dispersed onto cotton; populations on cotton could be predicted from the size of earlier populations on W. indica and subsequent rainfall.

This paper reports the data for the uncommon Anopheles spp. from 24-h man-baited catches mainly in the Semliki Forest, Uganda, but also from the Zika and Mpanga Forests Anopheles (Cellia) nili (Theo.), A. (C.) marshallii (Theo.), A. (C.) demeilloni Evans, A. (C.) squamosus Theo., A. (A.) coustani Lav. s. str. and A. (A.) tenebrosus (Dön.) were rarely caught. A. (A.) obscurus (Grünb.), A. (C.) moucheti Evans and A. (C.) keniensis Evans were also scarce, but the numbers did indicate nocturnal and ground-haunting habits. Comparison of catches of the less uncommon species (A. (A.) ziemanni Grünb., A. (A.) paludis Theo., A. (A.) implexus (Theo.), A. (C.) funestus Giles, A. (C.) hargreavesi Evans and A. (C.) pharoensis Theo.) with those obtained by other workers showed them to be primarily ground haunting and nocturnal but with wide variation in their temporal distribution patterns.

A total of 15 835 ticks was identified, mainly from sheep and goats, in a livestock survey in Cyprus in 1970–72. Hyalomma anatolicum anatolicum Koch, H. a. excavatum Koch, H. marginatum marginatum Koch, H. m. turanicum Pom., H. m. rufipes Koch, Haemaphysalis sulcata C. & F., Ixodes crenulatus Koch and Rhipicephalus turanicus Pom. & Matikashvili are recorded for the first time in Cyprus. H. sulcata was found in all parts of the island; Hyalomma spp. and Rhipicephalus spp. were mostly seen in the low drier areas, and Ixodes gibbosus Nutt. in the wetter areas; Boophilus annulatus (Say) was confined to one small area. Ticks were most common in autumn and early winter. Haemaphysalis sulcata and I. gibbosus were only found in the winter months, whereas Hyalomma spp. were found all the year round but especially in the warmer months. The Hyalomma subspecies showed some differences in seasonal distribution. Immature Rhipicephalus ticks were found in the colder months whereas the adults were seen mainly in the spring and early summer. Immature Haemaphysalis sulcata and Hyalomma spp. were extremely rare on ruminants. Only adults of I. gibbosus were seen in the first year of the survey, whereas only immatures, mainly larvae, were seen in the second year. The period of attachment of R. bursa C. & F. adults was shorter than that of R. turanicus and corresponded closely to the incidence of babesiosis in sheep and goats. The predilection sites of ticks for cattle, sheep and goats are given.

Most trapping techniques for estimating populations assume that all individuals are equally trappable. Where potential protein sources are used as baits for muscoid flies, which are known to have a cyclical intake of protein during ovarian development, numbers caught may not be comparable. Accumulated field data on the reproductive stages of samples of the bushfly (Musca vetustissima Wlk.) in a study area near Canberra have been analysed to show that only flies in the last stages of maturing their eggs (reproductive stage IV) are uniformly under-represented (about 22% of expectation) in baited samples.

An Elachistid moth whose larva mines leaves of sugar-cane in Papua New Guinea is described and named Eupneusta solena gen. et sp. n. The genus is differentiated from Dicranoctetes Braun, a New World genus which contains the Cuban species D. saccharella (Busck) whose larva is also a miner in leaves of sugar-cane. Descriptions of the larva and pupa are included, and special note is made of the highly developed spiracular processes of these stages.

The food and water requirements of adults of the blowfly Lucilia cuprina (Wied.), singly or in groups of ten, were recorded under laboratory conditions from the intake of water and of sucrose and bovine serum albumin plus liver extract, either in solution or in dry form. Water intake by both male and female flies is negligible when sucrose solution is available. When fed sucrose females live 18–19 days as opposed to 4–5 days on water alone. Intake of sucrose solution increases in both male and female flies when protein is also available. Protein is ingested from the day of emergence by both sexes of the blowfly. A peak of protein intake occurs early in each ovarian cycle of the female. The amount of protein feeding by females remains the same and appears independent of the sucrose concentration; carbohydrate uptake is inversely related to that of protein. In males protein intake declines steadily after an earlier lower peak. Knowledge of the dietary requirements of the blowfly, related to nutritional and reproductive demands, has allowed recognition of a series of behavioural phases in adult life.

The four components of the synthesised sex pheromone of Spodoptera littoralis (Boisd.) are tetradecan-1-yl acetate (I); cis-9-tetradecen-1-yl acetate (IIA); trans-11-tetradecen-1-yl acetate (IIB); and cis-9, trans-11-tetradecadien-1-yl acetate (III). Dissolved in hexane they were dispensed in small polythene containers either singly or in combination over water-trough (WT) traps located in the potato-growing region of south-east Cyprus. Only III was necessary to attract male moths. Increased loadings of III resulted in an increased catch during the 20-day test periods; at a loading of 500 μg per dispenser the material was attractive for approximately 20 days, and at 5000 μg for up to 40 days. IIA combined with III in WT traps or with virgin females in the vane traps markedly reduced the catch of male moths. The level of inhibition induced by IIA on the attraction of female moths was related to the loading of this substance in the dispensers. An inhibitory effect on the attraction of female moths in vane traps was also shown for cis-11-tetradecen-1-yl acetate, although this substance was less active compared with IIA at the same loading. No marked attraction or inhibition was shown for I or IIB, neither was any synergistic action demonstrated for these substances when in combination with III. When 200 polythene dispensers each containing 500 μg of III were evenly distributed throughout a potato field of 2000 m2 during the test period of 19 days virtually no males were caught in a trap baited with virgin females located in the centre of the field. Using only 100 point sources of III at twice the loading, only a slight reduction in catch compared with control catches was noted.

More or less cursory examination of migrating birds in Cyprus revealed 115 of 2580 southward (fall) migrants and 177 of 22015 northward (spring) migrants to be infested by 167 and 797 ticks, respectively. Most ticks on fall migrants were Hyalomma marginatum marginatum Koch; others were Ixodes frontalis (Panz.), I. ricinus (L.), Haemaphysalis concinna Koch, and H. punctata C. & F., all representative of the Eurasian fauna. Most ticks on spring migrants were H. m. rufipes Koch; others were Amblyomma lepidum Dön., A. nuttalli Dön., and A. variegatum (F.), representative of sub-Saharan Africa, and Argas streptopelia Kaiser, Hoogst. & Horner, Ixodes eldaricus Dzhaparidze, and I. redikorzevi Olen. which probably attached to the hosts in the eastern Mediterranean area. In Africa and Eurasia, 16 arboviruses have been recorded from eight of these tick species, and also the agents of boutonneuse fever, Siberian tick typhus, Q fever, and tularaemia. The epidemiological potential of migrating birds is enhanced by the multiplicity of pathogens that may infect them and the biological diversity of ticks that may infest them. The remarkably wide distribution of Crimean-Congo haemorrhagic fever virus in Africa and Eurasia is likely to be due to intercontinental carriage of the virus and ticks by migrating birds.

The results derive from three 24-h catches of Aedes aegypti (L.) (1190 females, 504 males) using human bait at Buguruni, Dar es Salaam, Tanzania, in April 1971. The diel periodicity of all females is predominantly diurnal (at least 99·83% arrive during daylight or twilight) and bimodal, with consistent peaks at 06.00–07.00 h (post-sunrise) and 17.00–18.00 h (pre-sunset). The diel periodicities of nullipars and pars, and of uninseminated and inseminated females are virtually identical. The diel periodicity of males is also bimodal but differs from that of females in that at least two-thirds (instead of about half) of the individuals arrive between noon and sunset, more activity occurs between 09.00 and 15.00 h, and the post-sunrise peak falls at 08.00–09.00 h. A large influx of nullipars one afternoon did little to modify the close correspondence between the diel periodicities of nullipars and pars on subsequent days. Females land on bait in all ovarian stages (I–V), but in these catches more than 80% of nullipars and pars were almost equally divided between stages I and II. Among nullipars relatively more uninseminated females, and among pars relatively more with relict eggs, land in stage I than do so in stage II. It is inferred that pars with relict eggs usually expel them between stages I and II. This work reveals the likelihood that (at least at Buguruni) the frequency of potentially infective bites on a given day could be monitored with acceptable precision by limiting the catch to seven hours and the part that was age-graded to two hours.

Potency in the male Culicoides melleus (Coq.) has been investigated by direct counts of spermatozoa liberated from spermatophores removed forcibly during copulation. At the first copulation, virgin males 12–24 h old transferred a mean (± s.d.) of 1156±210 sperm to the females. In a series of copulations in immediate succession (with a fresh virgin female at each mating in the series), the numbers of sperm transferred declined progressively to a mean of 72±88 at the seventh copulation. The percentage fertility was recorded in first egg batches oviposited naturally by females that partnered individual males at one of the copulations in an immediately successive series. Fertility remained essentially unchanged at its highest level (62–66%) for the first three copulations. It then declined through copulations 4, 5 and 6, and reached zero at the seventh copulation and beyond. The minimum number of sperm required to ensure full fertility in the first egg batch appeared to be about 600. Limited recovery of potency was exhibited by males mated three times in immediate succession, then kept 24 h and mated again.

Precipitin tests of the blood-meals of the non-anthropophilic population of Aedes simpsoni (Theo.) in Bwayise showed that at least 62% of the meals were mammalian; none was certainly avian or reptile. The remaining 38% were mostly too far digested for identification. Of the positive mammalian feeds, 84% were of rodents and only 5%; were of primates, probably human. In laboratory choice experiments, approximately two-thirds of a sample of the Bwayise strain fed on rodent in preference to monkey. Precipitin tests on blood-meals of the Bwamba strain of Ae. simpsoni confirmed earlier findings that this strain is strongly anthropophilic. At least 86% of wild-caught individuals had fed on mammals, 65% of these specifically identified: 28% of the feeds were of rodents and 72% were of primates, mostly human. During a five-month study at Bwayise in 1969, eleven species of rodents were caught; 91% of the rodents diurnally active were Arvicanthis niloticus which contributed 38% of the total collection and was twice as active during the afternoon as in the morning. The remaining species were predominantly nocturnal. A close relationship was found between the times of activity of A. niloticus and the biting cycle of Ae. simpsoni. In feeding tests using the three commonest rodent species, Ae. simpsoni selected A. niloticus as often as, or more often than, the nocturnal rodent species. This preference was maintained over one generation reared in culture. It is suggested that A. niloticus is the major natural host of the Bwayise strain by reason of the synchrony between rodent and mosquito activity rhythms. The Bwayise strain does not normally feed upon wild primates, so explaining further the almost total absence of human cases of yellow fever in areas of Uganda where this mosquito is non-anthropophilic.

A knowledge of the often complex relationship between insect populations and their effects on the yield-forming processes of crops is useful for assessing pest status and for devising methods of minimising the effects of infestation on yield. After a preliminary section on definition of terms, consideration is given to ways in which insects injure plants and crops, particularly annual crops. Investigations into the yield-forming processes of unattacked crops can often provide useful insights into the likely effect of insect injuries on yield. The differences between the characteristics of individuals and populations are discussed, both of insects attacking plants, and plants responding to the attacks of insects. The distribution of insects on plants and on crops and the effect that this has on damage is considered, as is the time and duration of the attack in relation to the growth cycle of the crop. The components of plant resistance to insect attack are then discussed, especially tolerance and the various ways in which plants and crops compensate for injury. The review concludes with an examination of the quantitative relationships between numbers of insects or injuries and their effects on yield. The generalised response is a sigmoid curve relating an upper and lower plateau of yield where changes in the numbers of insects or injuries have little effect. Most relationships conform to some part of this curve, though few show all its features.