In field experiments carried out at Kutsaga, Rhodesia, tobacco plants that had received high or low amounts of nitrogen, in addition to a basic dressing, were examined over five-week periods for the presence of alates and newly; deposited nymphs of Myzus persicae (Sulz.). It was found that settling and larviposition were reduced as a result of nitrogen deficiency in the plants, I apparently due more to some effect associated with slower plant growth than to reduced nutritional suitability. Washing with water enhanced the attractiveness of leaves in laboratory flight-chamber tests with alatae, suggesting the presence of a repellent substance on unwashed leaves. In flight-chamber tests with alatae, and choice-chamber tests with apterae, using artificial leaves made by forming Parafilm sachets on yellow Perspex discs, it was found that larviposition and nutritional suitability were related, and that both were affected by altering the balance of nutrients in the sachets, in the absence of any stimuli on the surfaces of the membranes.

A study of the egg shells of 11 species of Anopheles was made with the stereoscan electron microscope. A number of structures have been found that are useful in distinguishing between eggs of different species; all of them can also be seen with the light microscope. A list is given of these structures, together with others already known to be of taxonomic importance.

The functional significance of the network of the outer layer of the chorion of Anopheles eggs is discussed. It is suggested that the film of gas held by the network is of selective advantage in that it contributes to the buoyancy of the egg, provides it with a part of its protective coloration, and functions as a plastron when the egg is submerged. The plastron of A. labranchiae atroparvus Van Thiel resisted wetting at an excess pressure of more than half an atmosphere.

The relation of Anopheles eggs to the surface film is discussed. A highly stable line of contact with the water is formed, such that the water surface is depressed along the sides of the egg and raised at each end. Because like menisci are attracted and unlike ones repelled, eggs make contact with each other end to end or side to side, never end to side. Water spreads on most natural objects, forming menisci like those at the ends of the egg, which is thus provided with anautomatic trapping device that tends to attach the egg endwise to an object projecting from the water. The selective advantage of endwise over sideways attachment is not known, but it may facilitate hatching.

The structure of the egg of A. pseudopunctipennis Theobald has been disputed, and it is therefore described in some detail.

The use of chromosome translocations for the control of pests, with particular reference to Glossina, is proposed. A translocation arises if two non-homologous chromosomes in the same cell undergo breakage and the fragments re-join with the wrong partners. At meiosis in an individual heterozygous for a translocation, gamete nuclei with several different combinations of chromosomes are produced. Some of these are diploid for one part and lack completely another part of the normal chromosome set; when such unbalanced gametes fertilise normal gametes inviable embryos are produced. It has been found in a number of organisms that about half the gametes of translocation heterozygotes are of the unbalanced type and such heterozygotes are described as semi-sterile. If an individual inherits the same translocation from both parents it is described as a translocation homozygote; this is often inviable but, if not, its fertility is usually normal.

Adult males of G. austeni Newst. have been irradiated and each of their progeny are being screened for the occurrence of semi-sterility. Any individuals found to be semi-sterile would probably be translocation heterozygotes and their progeny will be inbred to try to produce a viable stock, homozygous for a translocation. If this can be done, large numbers of such translocation homozygotes could be reared and released into a wild population, where matings with wild types would produce heterozygotes, and hence a reduction in the fertility of the population.

Using simple assumptions, the effects of releasing translocation homozygotes were computed. Provided the numbers released were such that the translocation frequency approached the optimum value of 50 per cent., the reduction in population fertility would be prolonged for many generations after the releases had finished. It is shown that it would be more efficient to release the translocation homozygotes at successive generations rather than all at once and that the homozygotes released could with advantage be of both sexes. For this reason, and because of the prolonged effect of releases of translocations, it is concluded that the number of individuals that would have to be reared to achieve a given result by the translocation method might be considerably less than if the sterile-male method was used. However, the reduction in population fertility at each generation that can be achieved with the translocation method is limited, and the method would therefore be ineffective against populations whose size was strongly buffered by density-dependent factors.

A new species of Tachinidae, Mycteromyiella phasmatophaga sp.n., from Guadalcanal in the Solomon Islands is described and figured; descriptive notes and figures are also given for the related species M. laetifica (Mesnil), to supplement the original description. Both species are recorded as parasites of the Phasmatid Ophicrania levari Günther in the Solomon Islands.

A new species of Scirtothrips found damaging tea in Kenya is described and named S. kenyensis, and a note is given on damage caused by members of this genus. The name Heliothrips minutissimus Bagn. is suppressed as a synonym of Scirtothrips dorsalis Hood, and S. sweetmani Bianchi and S. tilschacki Ananthakrishnan are suppressed as synonyms of S. bispinosus (Bagn.), a combination that is here restored.

Three field trials with endosulfan against coffee berry borer, Hypothenemus hampei (Ferr.), on both Coffea arabica and C. canephora are described. The insecticide was applied from motorized knapsack sprayers at 20 gal. per acre of an emulsified solution containing 0.2 per cent, active ingredient to the branches bearing the crop.

In two trials endosulfan applied twice at 21-day intervals significantly reduced the numbers of cherries containing living borers and the percentage of damaged cherries at the first pick. In the third trial a single application of endosulfan proved to be as effective as the double one. Increases in yield could not be detected. It was shown, by allowing insects to emerge from caged samples of cherries taken when picking began, that endosulfan did not affect the host/parasite ratio of either H. hampei or Geratitis coffeae (Bez.), nor did it increase the numbers of berry-boring caterpillars.

No off-flavours following treatment could be detected in liquoring trials of robusta coffee beans that were dry processed or pulped and washed.

Laboratory experiments in which adults of H. hampei were exposed above, but out of contact with, filter papers that had been dipped in an emulsified solution containing 0·2 per cent, endosulfan showed that it was acting at least as a partial fumigant and was more effective at 30°C. than at room temperature (21°C); spraying should thus preferably be carried out on warm, sunny days. In view of these findings, and as it is relatively non-toxic, endosulfan is recommended for control of H. hampei in Uganda when heavy attacks occur.

An apparatus is described for applying a very small volume (0.1–1.0 μl.) of an insecticidal solution to an insect. It comprises a length of precision-bore glass capillary mounted, with a calibrated scale, in one end of a short tube having at the other end a perforated rubber bulb; the capillary is filled to the required scale mark by applying cotton wool saturated with the liquid to its tip, and the liquid expressed by squeezing the bulb, with the forefinger covering the hole in it. It can be used in conjunction with a calculator consisting of two concentric rotatable discs bearing two pairs of scales, on one of which the insect weight (in g.) is apposed to the per cent, concentration (w/v) of insecticide to be applied, which enables the volume (in μl.) required to yield a given dose (in μl./g.) to be read from the other pair of scales. Both devices have been used successfully in field testing with locusts and other insects.

Laboratory and field-cage studies were conducted in Texas in 1965 to evaluate treatments of the systemic insecticides, Azodrin (3-hydroxy-N-methyl-cis-crotonamide dimethyl phosphate), Bidrin (3-hydroxy-N, N dimethyl-cis-crotonamide dimethyl phosphate), American Cyanamid CL-47031 (cyclic ethylene (diethoxy-phosphinyl) dithioimidocarbonate) and Temik (2-methyl-2-(methylthio) propion-aldehyde O-(methylcarbamoyl) oxime), applied incorporated in lanolin to the stems of cotton plants against Heliothis zea (Boddie) and H. virescens (F.). Reductions in numbers of developing larvae of H. zea were substantial on individual plants the stems of which had been treated with Azodrin or CL-47031 and which were artificially infested with eggs. When first-instar larvae of H. zea or H. virescens were caged on plants 3, 7 or 14 days after stem treatment with 2.5, 5.0 or 100 mg. Azodrin, Bidrin or CL-47031 per plant, net mortalities ranged from 21 to 80 per cent after three days. The mortality of adults of H. zea provided with sucrose solutions containing 1 p.p.m. of the systemic insecticides indicated that Azodrin and Bidrin were about equally toxic and much more so than CL-47031 and Temik, and that of adults caged on individual plants in flower that had been treated with Azodrin or CL-47031 suggested that the moths may be killed by the systemic action of these insecticides translocated to the nectar. When adults of H. virescens were released on plants each treated with Azodrin at 25 or 30 mg. in large field cages, reductions in the numbers of eggs deposited, attributed to the effect on the moths of the insecticide in the nectar, and in the numbers of developing larvae, were substantial. Azodrin was the most consistently effective of the four insecticides evaluated.

In the laboratory, at a temperature of 30 ± 1°C. and 45 ± 2 per cent, relative humidity, the number of fertile eggs produced by females of Melanoplus sanguinipes (F.) that had copulated once and had then been reared alone in a cage was not significantly smaller than that produced by control pairs of males and females of this grasshopper. The solitary females laid more eggs than did the control females, but the eggs had a significantly lower percentage fertility. They also lived significantly longer, and one female produced eggs over a period of 140 days. Solitary and control females laid the same number of pods per day but the number of eggs per pod gradually decreased after the first two months of egg laying, particularly in the case of the control females, reflecting a decrease with time in the number of functional ovarioles.

The stick-insect Graeffea crouanii (Le Guillou) is a pest of coconuts of local and sporadic importance in the south Pacific and there have been recent outbreaks on Taveuni Island, in the Fiji group. As there appear to be virtually no parasites of the nymphal stages, a preliminary search was made in 1960 for parasites of other palm-feeding Phasmatids in Melanesia. This revealed the presence of Tachinidae parasitising species of the genera Ophicrania and Megacrania, and in 1963–64 these were studied in the Solomon Islands. The Tachinidae comprise at least two species of Mycteromyiella: M. laetifica (Mesnil) attacking both O. leveri Günth. and a species of Megacrania in the western Solomons, and M. phasmatophaga Crosskey attacking 0. leveri and some other Phasmatid hosts on Guadalcanal. The early stages of both species of Mycteromyiella are briefly described and compared, with notes on their bionomics. There was no evidence of any egg parasite attacking Ophicrania in the Solomons.

O. leveri, which is very closely related to G. crouanii, has never caused significant damage to coconuts in the Solomon Islands, except on the small island of Savo, from which its Tachinid parasites appear to be absent. It is concluded that Mycteromyiella, especially M. laetifica, which appears to be fairly specific, may be an important factor in the control of O. leveri in the Solomons.

The principal hosts of O. leveri are the sago palm (Metroxylon salomonense) and species of arecoid palms in the forest, on all of which the insect has better scope for concealment than on coconuts. Collections of nearly 6,000 examples of O. leveri from sago palm on Kolombangara island, in the western Solomons, in August 1963-February 1964 showed an average parasitism by Mycteromyiella laetifica of 28 per cent. Eggs of the Tachinid are laid on nymphs of all instars as well as on adults. The host-survival rate was about 30 per cent, for nymphs and 50 per cent, for adults.

A small number of parasitised specimens of O. leveri from Kolombangara were released on Savo, but there was no evidence six months later that M. laetifica had become established there.

Breeding trials at Honiara showed that O. leveri could be reared successfully in captivity but not M. laetifica, which shows reluctance to mate in cages and has a narrow range of environmental tolerance in the pupal stage, in which a mortality of at least 70 per cent, seems unavoidable under the conditions practicable for transportation of this stage by air.

Between October 1963 and March 1964 nearly 960 puparia of M. laetifica were sent to Fiji. About half of them were used for breeding trials, which showed that the Tachinid could be reared through G. crouanii in captivity but could not be maintained. The rest were released on Taveuni, but a further outbreak of G. crouanii during 1965 yielded no evidence that M. laetifica had become established.

Material of M. phasmatophaga, which has a more restricted choice of environment than M. laetifica, but also a somewhat greater potentiality for killing its host, was obtained by exposing O. leveri on seedling coconut palms planted in the forest at Honiara. Quantities were insufficient for transmission to Fiji; 150 parasitised hosts were released on Savo but samples of O. leveri collected there six months later gave no indication of its establishment.

Despite this initial failure, it is considered that Mycteromyiella could bring about the control of G. crouanii in Fiji and other affected Pacific islands, and the means by which this might be achieved are discussed.

Two new genera and species of Phycitinae found with Hypsipyla robusta (Moore) attacking Meliaceae in Nigeria are described. The three genera and species are differentiated, and the genus Hypsipyla is briefly reviewed. Illustrations of the wing venation and wing pattern of the adult male and of the genitalia of both sexes are given for the two species described as new, Catopyla dysorphnaea and Gyroptera robertsi, and also for H. robusta.

A Tortricid moth belonging to the Olethreutinae, bred from larvae feeding on the parasitic dodder Cuscuta reflexa in West Pakistan, is described as new and is named Herpystis cuscutae sp.n. The species is differentiated from the closely related H. jejuna Meyr., which occurs in India, and also from the two other Indian species of this genus, H. pallidula Meyr. and H. tinctoria Meyr. The status of the three specimens comprising the original type series of H. jejuna is re-evaluated, and one of them is considered to be probably conspecific with H. cuscutae.

In 1960–65, six field trials were carried out on tea estates in Ceylon to assess the effect on yield, and on the response of the crop to fertilizer, of dieldrin sprays applied after pruning to control shot-hole borer (Xyleborus fornicatus Eichh.). Periodic sampling was carried out to assess the numbers of borers and their galleries. Yields were recorded by weekly or fortnightly weighings of the green leaf plucked, over pruning cycles of two to four years.

The pattern of the yield increases on the sprayed plots was related to the difference in attack between the sprayed and unsprayed plots. Increases were, in general, small in the first year and much larger in the second year, reaching peak values of 32–58 per cent. (on the yields of successive three-monthly periods recorded) in the late second year, and declining thereafter through the third year as the difference in attack declined. Over the first two years there were marked yield increases in eight of the nine pruning cycles, and these ranged from 11·7 per cent, to 26·3 per cent. There was significant regression (P<0·001) of the percentage increase in yield on the maximum difference in gallery counts. Yield increases in the third year of pruning cycles were also considerable and the results evidence a prolonged effect of the heavy borer attack occurring in the second year.

In one trial there was a significant interaction between the effects of dieldrin spraying and of nitrogen supplied. Control of the borer greatly improved the crop response to nitrogen. Nitrogen application increased the yield but resulted also in a proportionately larger loss of crop from borer attack. There was a small but significant increase in the number of borer galleries on the plots receiving nitrogen.

The evidence on the size and pattern of crop losses caused by the borer suggests that these occur both from shoot breakages and from the direct effect of galleries on the growth of stems.

The significance of the results in relation to estate practice, and the economics of spraying, are briefly discussed.

The genus Nephotettix in Africa and Madagascar has been found to be represented by two species: one of them is N. modulatus Melich., the other is described as new and named N. afer sp.n. Both species are widely distributed in Africa, and a map is presented showing the countries in which each has so far been recorded.

Further evidence is provided to show that the head of the desert locust is the most vulnerable body region to the toxic action of malathion (and malaoxon). The circulatory system is shown to play an important part in determining the toxicity of the insecticide by taking it towards or away from the sensitive areas. The rates of absorption, distribution and excretion of 3H-malathion for different applications are given.

To find out if it were possible to reduce wireworm populations by means of seed dressings which are convenient to use, and desirable in other ways, the direct and residual effects of insecticides on wireworms (Agriotes spp.) attacking spring-sown and winter-sown wheat were tested on a clay soil at Rothamsted, Hertfordshire. Treatments comprised dressing seed with dusts containing 20% (standard) and 60% (high-rate) γ-BHC and 40% (standard) dieldrin, all at 2 oz. per bushel, 60% dieldrin at 70 oz. per bushel (high-rate), or a liquid containing 30% dieldrin at 1 fl. oz. per bushel; combine-drilling 0.5% γ-BHC dust at 1 cwt. per acre with the seed; and spraying the soil surface after sowing with 1 gal. 30% aldrin in 40 gal. water per acre. The high-rate BHC and dieldrin seed dressings, the combine-drilled BHC dust and the aldrin spray significantly reduced wireworm populations when applied to spring- or winter-sown wheat, the reduction in the former case being apparent two years later in one experiment; these reductions were, in general, reflected in increased yields. The standard seed dressings tended to be less effective. Similar results were obtained in an experiment on a fen peat soil in Lincolnshire.

Tests done in one experiment on plots sown with dieldrin-dressed seed showed no evidence that birds grub up plants or seeds that would otherwise have germinated.