Catches of Culicoides spp. in a Surrey copse in 1967–69 showed the univoltine C. impunctatus Goetgh. to be dominant. This species reached peak numbers from late May to early June, when nulliparous females were commonly seen at rest on tree trunks. Proterandry was marked in catches from light-traps but not apparent in those from emergence traps or taken at rest. Biting was most frequent 1–2 h before sunset; many bites did not result in a blood-meal. Females taken at rest and from emergence traps could complete their ovarian cycle without a blood-meal, most eggs being matured by the former; midges taken biting matured the fewest eggs but could not do so without a blood-meal. Large full fat-bodies were an indication of nulliparity. It was concluded that C. impunctatus can develop the first egg-batch autogenously, and that the resting habits and responses of females to light and human bait change subsequent to the laying of the first batch of eggs.

In laboratory experiments, the responses to short photoperiod (10 h) of clones of Myzus persicae (Sulz.) established from random samples of summer populations in southern England were generally stable and characteristic for each clone, and were of four distinct categories: (i) holocyclic, with clones terminated under short photoperiod by production of male and female sexual forms, (ii) intermediate, with a mixed response involving alatae intermediate between gynoparae and virginoparae, (iii) androcyclic, with production of some males along with continued parthenogenesis, and (iv) truly anholocyclic, with no significant response to short photoperiod. All four types can occur within one population, but holocyclic and androcyclic forms are most common. There were clear differences in the proportions of these forms occurring simultaneously on adjacent crops of different host-plants, and in different years on the same crop in the same field. Males of androcyclic clones were able to transmit their partially anholocyclic character through the sexual phase.

It has been proposed that the existing Organisation Internationale de Lutte Biologique (a mainly western European and Mediterranean body) should be enlarged and restructured to form a world-wide International Organisation for Biological Control. IOBC would be open to individual as well as institutional members, and would have largely autonomous regional sections in different parts of the world. IOBC is expected to come into being early in 1971.

Puparia of Glossina austeni Newst. and G. morsitans Westw. contain similar quantities of chloroform-soluble substances (referred to as fat) in relation to their nonfatty dry weight at the beginning of puparial life. However, adult G. austeni emerge from their puparia with significantly larger fat reserves than G. morsitans after development at 25°C. This obvious difference in the rate of fat consumption by puparia of the two species is not accompanied by differences in the rate of oxygen consumption, neither do respiratory quotients explain the difference. It is therefore concluded that some substrate other than fat may be used as a supplementary energy source in G. austeni, since there appears to be no species difference in the composition of fat. Thus the calculation of an oxygen equivalence of fat for tsetse flies is invalid for different species and may also vary within a species depending upon the temperature at which development proceeds.

The crops and guts of adults of Leptohylemyia coarctata (Fall.) from different parts of England and Scotland contained spores of Septomyxa affinis. This fungus is widespread on dead wheat leaves and grass in wheat fields and is an important food for the flies, especially in south and east England during July and August. Of all flies dissected in 1967, 1968 and 1969, 57%, 39% and 45%, respectively, contained Septomyxa spores. Spores of other fungi, pollen grains, bacteria and yeasts were also ingested. All solid food was ingested in water or honeydew. The weight of the newly emerged female fly almost doubled with the ripening of the first batch of eggs, whereas males remained the same weight or became lighter. Different individuals had different numbers of ovarioles, so the number of eggs ripe and ready to lay at the same time also differed between individuals. The mean numbers, 25·6 ± 0·8 in 1968 and 28·6 ± 0·4 in 1969 were fewer than the usually accepted 32. During August, before all the eggs had been laid, many flies were killed by Entomophthora muscae and Strongwellsea castrans.

One Nitidulid species, Cybocephalus semiflavus Champ, and two Coccinellid species, Chilocorus nigritus (F.) and Simmondsius pakistanensis Rafiq Ahmad & Ghani, commonly attack Diaspididae in West Pakistan. The known distribution and prey of each species are reviewed, and new records from West Pakistan given. The immature stages are described.

The development of Cybocephalus semiflavus from egg to adult was completed in 37–41 days at c. 26°C. Mating occurred 3–5 days after emergence and oviposition began 3–6 days later, 15–69 eggs being laid. An individual adult could consume up to 47 Diaspidid eggs daily, but all Diaspidid stages were attacked. In the field the predator persisted at low prey densities, but on Aonidiella orientalis (Newst), the preferred prey, its population rose in proportion to that of its prey.

The development of S. pakistanensis took 32–41 days from egg to adult at c. 24°C when fed on A. orientalis and Quadraspidiotus perniciosus (Comst). Mating was 8–11 days after emergence and oviposition began 6–11 days later, 153–242 eggs being laid. An individual could consume up to 35 Leucaspis coniferarum (Hall & Williams) daily. The predator was abundant during April-May, but later its effect was limited by Tetrastichus epilachnae (Giard).

At c. 24°C Chilocorus nigritus completed development from egg to adult in 33–40 days. Mating was 4–7 days after emergence, and oviposition began 8–13 days later, 228–351 eggs being laid. C. nigritus attacked several species of Diaspidids, an individual consuming up to 41 scales daily. The adults congregated on banyan trees during November-March in the coastal area and during September-June in the foothills, but dispersed to scale-infested plants at other times of year.

Transmission of cabbage black ringspot virus to turnip plants by Myzus persicae (Sulz.) was reduced by foliar sprays of five parts per million gibberellic acid together with 0·2% ammonium nitrate, but not by each applied separately. The reduction occurred at 10°C but not 15, 20 or 25°C, and at a light intensity of 10 000 lux but not at 5 000 lux. The response was usually only evident towards the end of the normal range of the incubation periods, indicating that protection was probably only achieved when relatively small amounts of inoculum were introduced. The reduced transmission could not be related to aphid behaviour but changes were found in the free proline content and fine surface structure of treated leaves, and it is suggested that the results are to be interpreted in terms of changes in host cell metabolism.

Standard text-books on entomology (Imms, 1957; Ross, 1956) state that the insects of the order Thysanoptera feed by macerating leaf tissue with pointed stylets, and then suck the juices thus released by applying their mouth cone to the leaf surface.The drawings accompanying these statements indicate that the maxillary stylets and the single mandible are all simple acute needle-like structures. However, sections of the mouth cone including the stylets show that the mandible is a closed tubular structure, and that the maxillary stylets are grooved, i.e., C-shaped in section (Reyne,1927; Mickoleit, 1963). Moreover, Grasse (1951) states that although the maxillary stylets do not show the mutual adaptations found in the Hemiptera they do form a tube when fitted together, and Grinfel'd (1959) suggests that thrips may suck food through the tube formed by the stylets in addition to applying the mouth cone directly onto the food.

Previous work on Phlebotomines has shown that most parous flies in many species may be recognised by the dark residual secretion in the accessory glands; parity can be confirmed by inspection of ovarioles. In the present study 12 species of Lutzomyia were caught in forests near Belém, Brazil, mainly with rodent-baited oil-traps. Many females of the predominant species, L. flaviscutellata (Mangabeira), were parasitised by the protozoan Monocystis. Parous rates based on examination of ovaries were subject to an error of about 5% due to diminution or disappearance of follicular relics. Two successive dilatations of the tunica were seen in L. davisi (Root), suggesting that it had laid two batches of eggs. Biting rates by parous flies varied little during the night, and were somewhat less than those of nullipars. In eight species the dark-gland rate approximated to the parous rate as shown by the ovaries; a small error may have been due to discharge of all secretion, disappearance of follicular relics and premature activity of glands. In contrast to this concordant pattern, four species showed discordance, possibly due to autogeny. It seems advisable to omit oil-trapped blood-fed flies when estimating parous rates by examining glands. Monocystis may increase the dark-gland rate, but it is non-pathogenic or has little effect on life span, and does not hinder blood-sucking.

The effects of sublethal doses of insecticides and unrelated environmental stresses on Dysdercus fasciatus Sign, were studied in the laboratory. Dieldrin applied topically to fifth-instar nymphs at 02–0·6 μg/individual increased egg production, at 0·8–60 μg/individual decreased egg production, and at 0·6–60 μg/individual decreased fertility. Applied to adults, dieldrin at 2–4 μg/individual reduced egg production, and at 0·02–0 08 μg/individual (males) and 0·2–0·8 μg/individual (females) shortened the life span. In a separate experiment, dieldrin at 0·2 μg/individual reduced egg production when applied to fourth-instar nymphs, but had no effect on fifth-instar nymphs or adults. p.p'DDT at 6 μg/individual applied topically to unmated females increased egg production. Exposure of all life stages to 0·06 mg DDT/ litre for two generations was followed by increased egg production and fertility: shorter exposure at 1 mg DDT/litre had no effect, and at 6–20 mg/litre egg production and fertility were reduced. Rearing on boiled cotton seed resulted in small adults with low gg production and fertility, the eggs being longer than normal. Crowding nymphs (24 individuals/200-ml cage) had the same effect on the size of the resultant adults. Starvation caused low egg production and fertility. Fluttering of males during a free fall (a measure of activity) was increased by crowding (maximum at 2 individuals/cage), by topically applied dieldrin at 0·04–0·08 μg/individual and DDT at 3–5 μg/individual, by two-generation exposure to 0·06 mg DDT/litre, but not by feeding on boiled cotton seed.

Sixty-one Culicoides spp. were collected in Kenya, Uganda and Tanzania between January 1966 and December 1967 using light-traps at 35 stations on a NW-SE transect from the Indian Ocean to central Uganda to evaluate the distribution of Culicoides spp. among ecological zones. Most species were confined to one or at least very few similar habitats. The largest number of species (30) occurred in the forest zone, probably because of the many suitable breeding sites, whereas only three species were recorded from the dry bushland zone. Forests also contained more exclusive Culicoides spp., whereas savanna species showed a wider distribution, suggesting that the forest species are less adaptable than others. The disease vectors C. grahamii Aust. and C. pallidipennis C, I. & M. were among the most abundant and widely distributed species.

The optimum size range of particles of two carbamates and two organophosphorus compounds in deposits on plywood and plaster for contact toxicity to blood-fed females of Anopheles stephensi List, was 5–30 µm. The effect of particle size on the contact toxicity of these compounds of high intrinsic toxicity was not great and in this respect resembled that found previously for dieldrin and γBHC. In the few tests done, the concentration of active ingredient in wettable powder formulations was not an important factor in determining the contact toxicity of deposits of such toxic materials.

An experiment was carried out in 1968 in the Lossitete Forest area of northern Tanzania to compare the fly-round and the Langridge-trap as sampling techniques for assessing the effectiveness of 0·4% pyrethrum applications on Glossina pallidipes Aust. when applied from the air. From fly-rounds, population reductions of 64%, 36% and 29% after the first, second and third applications, respectively, were estimated, whereas from Langridge traps the reductions were 11%, 7% and nil, respectively. Taking into consideration the efficiency of the Langridge-trap and the limitations of the fly-round in sampling G. pallidipes populations, it is concluded that the fly-round may give a false assessment of reduction of G. pallidipes after insecticide application.

The black citrus aphid, Toxaptera aurantii (Boy.), produces a distinct scraping sound by rhythmic movements of whole colonies. It is the only species of aphid known to produce audible sounds and the acoustical content of a preliminary recording of these sounds is reported in detail. During one recording the aphids stridulated 15 times in 21 seconds, giving an average period of 1–4 seconds between emissions and this rate remained virtually constant for at least an hour. Analysis of the recording established a clear peak frequency band at about 4–6 kHz with another around 800 Hz-1 kHz and possibly another in the ultra-sonic range above 18 kHz. Morphological adaptations of the abdominal cuticle and of the hind tibiae to form a stridulatory apparatus are illustrated and possible functions of stridulation as a defence mechanism or as a means of intraspecific communication are briefly discussed.

A simple X-ray method for detecting sorghum midge (Contarinia sorghicola (Coq.)) larvae and pupae in infested spikelets of grain sorghum (Sorghum vulgare) is described and illustrated. Undamaged ovaries were easily and accurately detected in the radiographs, but the detection of spikelets that had been attacked by midge was less accurate. Diapause larvae showed up clearly in the radiographs but pupae often produced indistinct images, possibly because they were dead. X-ray examination therefore tended to underestimate midge infestation. It is concluded that this radiographic technique is less accurate than dissection, but might be used for rapid general field surveys and for in vivo observations of larval development within infested spikelets.

Infestations of Dermestes maculatus Deg. in dried fish at Dugbe market, Ibadan, are favoured by traditional packaging and display methods. In laboratory experiments last-instar larvae and adults showed low thigmokinesis and a bias towards the dry end of a 50–100% r.h. gradient; in alternative humidities between 40% and 100% last-instar larvae and adults selected 60–80% r.h., adults having a stronger preference than the larvae for the higher humidity; in a temperature gradient last-instar larvae and adults avoided the 30–45° C zone and showed low thigmokinesis and immobilisation at 19° C. These findings were generally consistent with observations in the market. Heating dried fish in an oven at 60° C for 30 min killed all larvae and adults of D. maculatus present. Two 30-min heat treatments at four-day intervals in a simple charcoal-fired oven and storage in metal containers would control the pest.

Field experiments were conducted in the Gambia to measure the convergence of mosquitoes towards single bait-animals (calf or man) or to an equivalent source of carbon dioxide, the mosquitoes being caught in ramp-traps. Catches of unfed females of Anopheles melas Theo. fell off steeply with increasing distance up to 15 yd from animal bait; with carbon dioxide as bait, raised catches were only recorded out to 10 yd. Catches of other Anopheles spp. with calf-bait gave similar results to those for A. melas. A positive effect of the calf on densities at 15 yd was obtained for Culex tritaeniorhynchus Giles but this was less clear-cut in the case of C. thalassius Theo.; with carbon dioxide as bait, raised catches of both species were recorded at 10 yd but not at 15 yd. Both types of bait gave raised catches of the C. decens group only at 5 yd. It is concluded that A. melas and other Anopheles spp. were detecting and responding to the single animal bait from 15–20 yd, C. tritaeniorhynchus and C. thalassius from 10–20 yd, and the C. decens group from 5 yd. In all except the last named group, as also for the other Anopheles spp., on which data are lacking, the range of attraction of carbon dioxide was less than 15 yd. Olfactory cues were therefore held to be responsible for long-range orientation in these three species of mosquitoes, the effect being most marked with A. melas.

Between 1961 and 1967 intensive and extensive field studies on the sugar-cane pest Saccharosydne saccharivora (Westw.) were carried out in Jamaica (with supplementary observations from British Honduras). Egg populations were scored for size, and egg mortality and nymph-adult parasitism were estimated directly. In epidemic, but not endemic, populations, successive generations of the pest were segregated and their development was synchronised over areas of up to 80 miles2 despite its 6½—7-week life-cycle and potential for continuous breeding. Segregation was due to the sterilising action of the parasite Stenocranophilus quadrat us Pierce (Halictophagidae); in the drier months this spread so rapidly through the nymph and adult population that oviposition ceased until the first adults of the next generation reached maturity. In the wet season this effect was complemented by the entomogenous fungus Metarrhizium anisopliae. Synchronisation was ensured by the dispersal of parasitised adult Saccharosydne saccharivora before oviposition. In ratoon cane there were six or seven generations between successive annual harvests; egg populations were highest in generations 1–3 (up to 1·0×106/chain-row (≡2O·2-m row-length)), and declined in old cane irrespective of season. In plant cane, egg populations did not show a decline with age and sometimes increased. In epidemic areas a factor associated with older cane sometimes caused over 90% egg mortality; elsewhere Tetrastichus sp. (Eulophidae) was the leading cause of egg mortality (ca 30%). Data from extensive surveys showed that the early stages of outbreaks were invariably associated with plant cane; heavy infestations rarely occurred on cane subjected to adverse growing conditions; and populations were smaller on the variety B42231 than on B4362 and B41227. Outbreak periods since the 18th century have been associated with periods of prosperity within the sugar industry, when presumably more attention was paid to improving production. Rainfall, in that it improves cane growth, is beneficial to S. saccharivora, whereas drought is detrimental; published records of outbreaks in dry periods are due to the preference of migrating adults for young cane which is most prevalent in the dry season. It is concluded that the essential prerequisite for an outbreak is plant cane growing under favourable climatic and agricultural conditions; present conditions, namely the long harvest period, high standards of cultivation, irrigation and fertiliser practice, and favourable cane varieties together offer the minimum chance for a natural end to outbreaks.

Studies on the egg diapause of Teleogryllus commodus (Wlk.) in southern Victoria, and the effect of latitude on the intensity of diapause in Teleogryllids have led to the concept of population suppression by the genetic elimination of diapause. The method is based on the finding that males of the closely related T. oceanicus (Le Guillou) transmit the non-diapausing trait when crossed with T. commodus females. An additional suppressive factor is imposed by sterility in the progeny of the cross. An evaluation of the feasibility of this approach has been carried out in small-scale trials using field enclosures in which known populations of both types were studied. With a 10:1 ratio of non-diapausing/diapausing males, a mean of 73–8% of the eggs from the T. commodus females were hybrid, and with a 5:1 ratio 50–8%. The practical application of the method will not be attempted until the relative suitability of a number of candidate non-diapause biotypes has been determined.

The relations of the Strepsipterous parasite Halictophagus pontifex Fox to seven species of its Cercopid (Aphrophorinae) hosts were studied at a grassland site in Uganda. Dissections of weekly samples of the Cercopids collected by sweeping showed that the duration of the life-cycle of H. pontifex is 30–40 days. The parasite is found only in adult hosts which can support as many individuals (up to 7) in Poophilus costalis (Wlk.) as can develop in the space available in the body cavity. Both the maximum number of parasites per host and the rate of parasitism are related to the volume of the host. Parasitism arrests development of the ovaries of female hosts; they may reproduce after emergence of male parasites but not after exhaustion of females because of reinfection by triungulins. Graphical and regression analysis of the population data (no. individuals/1 000 sweeps) show that, for P. costalis, parasitism by H. pontifex is density dependent and the chief regulating factor. Rainfall 58–64 days before sampling also was correlated with P. costalis density, but multiple regression analysis showed it to be insignificant.