A species of Mompha, discovered on creeping water-primrose Ludwigia adscendens (Onagraceae) in Assam, N.E. India, is described as new and named Mompha ludwigiae. The eggs, larval and pupal stages are also described. Females lay up to 150 eggs in 3–7 days; development from egg to adult takes 3–5 weeks, the larva at first mining the leaves and later feeding externally on terminal shoots. The larvae could be reared on Oenothera rosea, L. perennis and L. octovalvis in the laboratory, but no host-plants other than L. adscendens were found in the field. A Eulophid parasite, Euryscotolinx sp., has been bred from pupal cocoons.

Analysis of the results obtained from suction-trap catches of the coffee leaf-miners, Leucoptera meyricki Ghesq. and L. caffeina Wshbn. on an unsprayed block of coffee at the Coffee Eesearch Station, Lyamungu, on the slopes of Kilimanjaro, are given.

By thermal summation methods it was possible to delimit successive generations of moths with some degree of accuracy and the generation catches were used for regression analysis with various meteorological factors. With L. meyricki, a negative correlation was shown between the rate of increase from one generation to the next and with both maximum and mean daily temperature, solar radiation and duration of sunshine taken as means over the period of each generation. In each case, the highest degree of correlation was found between the meteorological data in one generation and the rate of increase in the next.

When the generation catches were plotted on a logarithmic scale it was found that linear regression lines could be fitted to the periods of both rise and fall of the annual outbreak. With L. meyricki, the rate of increase of the rise was negatively correlated with, and the rate of decrease of the fall positively correlated with, the size of the generation present at the beginning of the outbreak. It is therefore possible, knowing the size of the minimum generation, to predict the size of the coming outbreak. No such relationship could be proved with L. caffeina, probably because the catches of the key generations were very small, but when the catches of the two species were pooled the same relationship held. It is probable that parasites are the main factor governing the annual fluctuations.

The mid-winter development, reproduction and survival of field-acclimatized viviparae of Sitobion avenae (F.) and Rhopalosiphum padi (L.) on leaves of tillering wheat and perennial ryegrass (Lolium perenne) plants at similar growth stages were compared by monitoring batches of aphids in clip-cages in field plots in southern England. For both aphid species, survival, total fecundity and reproductive rate were much higher on wheat than on L. perenne, and on both host-plants they were much higher for S. avenae than for R. padi. Development times (in day-degrees) were longer on L. perenne than on wheat, and on both host-plants were longer for R. padi than for S. avenae, though these differences were less marked. Comparison of the results with those of earlier studies suggests that large changes in cereal aphid performance occur between summer and winter and that these are both aphid-specific and host-plant-specific.

When Myzus persicae (Sulzer) feeds on healthy sugarbeet it develops a white precipitate inside its stomach which causes the stomach to enlarge. Infection of sugarbeet plants with beet yellows virus (BYV), but not beet mild yellowing virus (BMYV) results in further increases in stomach size. The influence of the white precipitate on the transmission of BYV and BMYV was investigated by rearing M. persicae on sugarbeet Beta vulgaris, Tetragonia expansa and Capsella bursa-pastoris, which are hosts for both BYV and BMYV, BYV and BMYV respectively, but the latter two hosts do not stimulate the formation of white precipitate in the aphid's stomach. Aphids reared on BYV-infected T. expansa were significantly better vectors of BYV than those reared on BYV-infected sugarbeet, but aphids reared on BMYV-infected C. bursa-pastoris did not transmit BMYV more efficiently than those reared on BMYV-infected sugarbeet. The consequences of these results for the spread of beet yellowing viruses are discussed.

The braconid larval parasitoids Cotesia chilonis (Matsumura), C. flavipes Cameron and a strain of Cotesia sesamiae (Cameron) from coastal Kenya, reared at the International Centre of Insect Ecology and Physiology, were introduced at the International Institute of Tropical Agriculture in the Republic of Benin for suitability testing on West African stemborers prior to release. C. chilonis was originally collected in Japan while C. flavipes was imported into Kenya from Pakistan. The host species used was the noctuid Sesamia calamistis (Hampson), the most important noctuid maize pest in the region. All three Cotesia species attacked and successfully developed in 2nd to 6th larval instar of S. calamistis but parasitoid-induced mortality was highest on second instars. On most instars, C. sesamiae and C. flavipes produced larger broods than C. chilonis. Larvae parasitized by C. sesamiae developed to the 6th instar and attained an average larval weight of 353 mg, while larvae parasitized by C. chilonis only molted to the 4th instar and attained a maximum weight of 107 mg. The lower developmental threshold estimated from the non-linear regression of temperature on developmental rate was 15.9, 15.9 and 14.9°C for C. chilonis, C. sesamiae and C. flavipes, respectively, while the maximum temperature was 34.2, 35.2 and 33.8°C, respectively. A maximum of four ovipositions were observed per female during a life span ranging from 1.3 days for C. chilonis and C. flavipes to 1.6 days for C. sesamiae. The largest adult progeny, intrinsic rate of increase and net reproductive rates were recorded at 28°C for all species. However, across temperatures, C. flavipes yielded the highest number of offspring, followed by C. sesamiae and C. chilonis. The sex ratios did not vary significantly with species and temperature. Thus, the reproductive potentials of C. sesamiae and C. flavipes were greater than that of C. chilonis.

The writer's original intention in publishing this paper was to give a key for the identification of those African mosquitos which might be taken by the nonspecialist for species of Culex, without attempting to form any opinions as to the value or limits of allied genera. A study of the insects, however, led to the realisation that scale characters, in this group at least, are not of very great value for separating genera, and consequently the present paper gives the author's views of the classification of the Culex group, and is more complete than it might otherwise have been. Time has not yet been available to deal with those species which have flat scales on the top of the head or on the scutellum (Stegomyia group).

Seven strains of Aëdes aegypti (L.), three DDT-resistant (from Trinidad (2) and Haiti) and four susceptible (from West Africa (2), Arabia and U.S.A.) have been investigated with respect to their attraction to oviposition sites illuminated at different levels. The resistant strains have tended to choose the darker sites (at 0·02 lumen per sq. ft. and below) and susceptible strains those illuminated at between 3·5 and 6·5 lumens per sq. ft.

Genetical crosses between a ‘dark-laying’ (resistant) strain and a ‘light-laying’ (susceptible) strain indicated that ‘light laying’ was fully dominant over ‘dark laying’ and it is suggested that the mechanism involved is probably simple. No linkage with the gene for physiological resistance to DDT could be demonstrated.

The expressivity of this character varied in certain circumstances with a tendency among most strains to lay at darker sites after the second and subsequent blood-meals. In spite of these variations, behaviour at any one time remained reasonably predictable.

The reflectance of the oviposition site did not appear to be important in determining the difference in behaviour between ‘dark-laying’ and ‘light-laying’ strains. On the contrary, it seemed probable that ‘dark-laying’ strains were attracted more to the dark situation in which the dimly-lit site was found rather than to the site itself. There was some evidence of exploratory activity in the initial stages of oviposition by a ‘dark-laying’ strain.

Resting habits proved very similar in two strains differing markedly in oviposition habit. For both strains, 0·1 lumen per sq. ft. was apparently too low to be attractive and 12 lumens per sq. ft. too high. Besting behaviour did not appear to be under such critical control by light as was oviposition.

Possible explanations for the differences in ‘oviposition light preference’ are discussed.

The following report deals with the investigation into the bionomics of Glossina morsitans being carried out in Northern Rhodesia on behalf of the British South Africa Company.

On my return from leave in July 1914 it was decided to form a base camp close to the railway line. Several areas in the neighbourhood of Broken Hill where fly was reported as being very thick were first examined, but were found from various causes to be unsuitable. A site was finally selected at the source of the Lukanga River, about four miles from the line and near Kashitu station, midway between Broken Hill and Ndola. Building was commenced in August and completed in October, just before the commencement of the rains.

Messrs. Eminson and Dollman, who had been working on the Kafue River at Mwengwa, had just reported the discovery of Mutilla glossinae, Turner, a wasp parasitic on the pupae of G. morsitans and of considerable importance, since the former worker found that about 10 per cent, of the 350 pupae he had collected were destroyed by this insect. This is the first insect parasite of any tsetse to be found in numbers, and it was decided to let the future investigations centralise round it. In order to discover whether it was localised or generally distributed, a tour was made through the fly areas of N.E. Rhodesia during the dry season of last year (1915) for the collection of pupae in various localities. About 4,000 were collected and examined. May and July were spent at Chutika (Hargreaves) in the Luangwa Valley, part of August at Nawalia in the Mpika section of the same valley, and September at Ngoa on the plateau near Mpika. Breeding was found to have commenced in the Luangwa Valley about the middle of April, and by the time the plateau was reached it was at its height. Before dealing with the parasites found, some general questions will be discussed.

Toxoptera victoriae sp. n. is described from Hong Kong. The economic importance of the genus Toxoptera is discussed. Separate keys are provided to adult and first instar larvae of the species of Toxoptera.

Insecticidal treatments against Heteronychus consimilis Kolbe, a serious pest of wheat in Kenya, killed large numbers of adults and markedly reduced the damagedone by them. Subsequent damage by larvae was prevented.

The most effective of the treatments tested were aldrin at 7.2 oz. per acre applied with the fertiliser, BHC in the form of Mergamma A applied as a seed dressing at 3¼ oz. per acre, and BHC in the form of Agrocide 7 applied as a seed dressing at 3¼ lb. per acre. The best treatments resulted in considerable increases in yield and gave promise of effective practical control on a large scale.

A year-long survey of the breeding of Glossina morsitans Westw. in the Moremi Game Reserve, northern Botswana, was based on transect counts of pupae and empty puparial cases under logs. Levels of breeding were lowest during the hot dry months, and were similar in riverine woodland and mopane even when the latter was leafless: mopane contributed most pupae (65.7%) to the total population because of its greater area. Pupae to cases ratios decreased between February and November due to accumulation of cases, which apparently were largely destroyed in the rains. Comparison of holes, scattered sites and logs in a second survey showed that holes were important breeding sites during the hot dry season, possibly due to their higher humidity, but that at other times most breeding occurred in scattered sites. During the rains scattered sites contained the fewest dead pupae, and holes the most. There was a preference by G. morsitans for shaded sites. Breeding appeared to be depressed during the rains, possibly due to reduced availability of food hosts, particularly warthog.

A laboratory colony of Glossina morsitans orientalis Vanderplank had been kept successfully in Edinburgh for 18 months, when reproduction ceased because of a high incidence of abortion and follicular degeneration. A comparison of these flies with imported Bristol-bred flies showed that the latter reproduced well under identical conditions, but since Edinburgh-bred progeny of imported flies also showed poor reproduction, a genetic difference between the two populations could be ruled out. Comparisons of the progeny of flies fed on human and rabbit blood, and of the progeny of flies fed on rabbits maintained on different diets, produced strong biological evidence for a toxicant in one of the diets which produced reproductive abnormalities in the Ft generation of flies. The trouble was thus traced to a change in rabbit diet which took place about a month before the appearance of the reproductive disorders. It is suggested that the toxicant, which remains unidentified, is concentrated by the parent female in the accessory gland secretion and thereby incorporated into larval tissues during intra-uterine development.

Each spherical spermatheca of Glossina austeni Newst. is composed of a cuticular lining of the lumen which is surrounded by a layer of secretory cells. When the spermatheca is immersed in Amann's lactophenol the cells of the cellular layer lift away from the cuticular intima revealing numerous clubbed processes projecting outwards from the surface of the intima. Sections of spermathecae examined by transmission electron microscopy show that one clubbed process is associated with each cell of the cellular layer. The “porous” head of the process is within a fluidfilled cavity in the cell, lined with microvilli. The stalk of each process is an extracellular duct down which secretions from the cellular layer pass into the lumen of the spermatheca. It is considered that these secretions are the medium, probably containing nutrients, in which spermatozoa are held while in the spermatheca.

Planthoppers are important worldwide crop pests as well as vectors of numerous diseases. Different species transmit Mal de Río Cuarto virus, which causes the most economically important corn disease in central Argentina. Epidemiological studies rely on the accurate identification of the species present in the field. Presently, morphological identification of planthoppers requires taxonomic expertise and there are no taxonomic keys for females and nymphs. Nevertheless, no molecular protocols are available for accurate species identification of most frequent delphacid species from central Argentina. In this context, the aim of this study was to evaluate the utility of the cytochrome oxidase I gene (COI) as a DNA barcode and its digestion with restriction enzymes (Restriction Fragment Length Polymorphism, RFLP) for the identification of the most common species of planthoppers in central Argentina. We amplified and sequenced a 843 bp fragment of the COI gene of taxonomically identified specimens and evaluated its use as a DNA barcode. Restriction enzymes were also selected for digesting the COI fragment via RFLP. The high interspecific variability (20.79%; ± 2.32%) and low intraspecific divergence (0.12%; ± 0.17%) observed in the studied species, demonstrate the effectiveness of the COI gene for species identification of major vector delphacids affecting corn crops in Argentina. Moreover, the digestion of this COI gene fragment with Bfa I and Apo I enzymes allows a fast and cost-effective species identification method when numerous specimens need to be processed. Both molecular techniques developed here, allow the accurate identification of planthopper species at regional scale. These new tools would assist traditional identification of these insects, especially for aiding non-experts in morphological taxonomy.

Experiments were carried out during 1945 and 1946 to determine the effect of insecticides, particularly DDT and BHC, on certain species of Syrphids and Coccinellids. In addition, some preliminary data was obtained on toxicity to parasitic Hymenoptera and a predatory Cecidomyiid species.

In some experiments other insecticides were used for comparative purposes and where possible data were obtained on the effect of the insecticide not only on the predator but also on the host and the host-predator relationship.

The object of this paper is to supplement an article which appeared early in 1914 in the Journal of the Board of Agriculture of British Guiana (Vol. iii, No. 3.) At that time it was proposed to publish a further account of these insects as soon as more species had been collected and identified, and fuller information gained. Also, taking into consideration the great economic importance of the Coccidae, it has been deemed advisable to disseminate as widely as possible all information which has been acquired concerning them locally. In the previous article, some fifty-one species were enumerated and notes recorded concerning their habits and economic importance. In this paper information appertaining to sixty-eight species is given, a number of which are new to science. Further knowledge with regard to the parasites and predaceous enemies has been gained, as well as their economic status.

Simuliid larvae and pupae found in phoretic association with the fresh-water crab, Potamonautes niloticus (M.-Edw.) in Kenya rivers far from the haunts of Simulium neavei Roub. gave rise to adults which proved to be S. nyasalandicum De Meillon, a member of the neavei group. Very similar larvae, and pupae that exhibited minor differences from those of S. nyasalandicum, were found in the exhalant passages from the gill chamber of the crab. These yielded adults of S. woodi De Meillon, and no other species was found in this particular situation; nor were examples of S. woodi found on the external surface of the crab. As many as three larvae were found in one passage and, in another crab, a fully grown larva and pupa caused complete obstruction of the passage on one side. Apart from the security enjoyed by the larva in the sheltered position, it is thought probable that the association is essentially a commensal one.

The behaviour of mosquitos in contact with deposits from aqueous suspensions of insecticides has been studied by allowing them to alight individually and measuring the time to the first flight.

Anopheles stephensi females flew from all formulations of DDT on various materials after approximately the same time of 2 to 4 minutes, but subsequent kills were high only when the deposit consisted of small (less than 10 microns) particles readily available for pick-up.

Mosquitos were also activated by contact with fresh deposits of BHC wettable powder P.520, but all died very quickly. They were not disturbed, however, by the vapour from BHC deposits, when contact was prevented, until in an advanced stage of intoxication. The time to the first flight from surfaces treated with BHC wettable powder increased as the deposits aged and varied with different materials according to the rate of loss by evaporation and/or sorption.

Mosquitos remained in contact with deposits of chlordane, dieldrin, aldrin and toxaphene for more than 30 minutes.

Experiments with a number of DDT analogues and BHC isomers indicated that lipoid solubility and molecular structure are two factors governing the rate of penetration of a compound.

The reactions of other species tested were similar to those of A. stephensi but kills of Culex p. molestus were significantly different from those of the Anopheline species after contact with deposits from a DDT wettable powder.

1. To determine the percentage hatch of Calandra granaria eggs, the grain containing them should be kept for 6–10 days at 25°C. after a two-day oviposition period.

2. Pretreatment of grain with mercury vapour makes no difference to the fertility of eggs afterwards laid in it.

3. At 25°C. 99 per cent. of the eggs are sterilised in 24 hours and 87 per cent. in 8 hours, using what probably approaches the saturated vapour.

4. At 10°C., the sterilisation for periods of 24, 48, and 72 hours is 44, 87 and 93 per cent. respectively.

5. At 25°C., mercury vapour will penetrate at least 30 cm. of grain in 2 days. At 12°C., mercury vapour will penetrate at least 90 cm. of grain in 7 days.