During the study of the Nearctic Tachinidae it became obvious that, in order to secure an adequate idea of the relationships of the various genera, it would be advisable to study representatives of the family from all parts of the world, and requests for African material met with hearty response from several sources. The extensive collection made by the American Museum of Natural History Congo Expedition has already been dealt with, and the report will appear elsewhere. Mr. H. K. Munro, of Pretoria, South Africa, has forwarded his entire collection with the request that it be worked over, since very few of the species were determined. Dr. Guy A. K.Marshall, Director of the Imperial Bureau of Entomology, has also been kind enough to forward a large amount of material, and a great deal more has been promised from other sources. It was originally intended to prepare a synopsis of the South African Tachinidae preparatory to a more detailed study. However, the large number of species and genera represented in the thousands of specimens at hand makes such an undertaking so extensive that it is deemed advisable to report upon certain genera or larger groups in order that most of the material may be returned to the owners, retaining such specimens as may be necessary for further study.

In response to the expressed desire of Mr. Arthur Gibson, Dominion Entomologist, to introduce European parasites to aid in controlling the Western Wheat-stem Sawfly, Cephus cinctus, a shipment of 15,000 wheat stubs containing parasitised Cephus pygmaeus was forwarded to Canada from the Farnham House Laboratory, Farnham Royal, Bucks, England, in the early spring of 1930. This stubble was received at the Dominion Parasite Laboratory, Belleville, Ontario, and was there held in cold storage until reshipped to Western Canada, where the parasite, Collyria calcitrator, was to be liberated.

A short history of the study of the six tsetse species of the group of Glossina fusca (Wlk.) that occur in Nigeria and the former British Southern Cameroons (now West Cameroun, part of the Federal Republic of Cameroun) is given. Extensive collections of these species were not made until after the scheme for the establishment of the West African Institute for Trypanosomiasis Research was initiated in 1947. More intensive studies, stimulated by the discovery of a technique of searching for the flies in their resting sites, were carried out in southern Nigeria, at the W.A.I.T.R. Field Station and elsewhere, from 1953 onwards.

The situation, climate and vegetation zones of Nigeria are described. Species of the fusca group occur only in the southern part of Nigeria and in West Cameroun and depend on some type of forest vegetation, ranging from relatively dry forest islands and riverine forest in savannah to dense, humid, wet rain forest, for their habitat. Rainfall and relative humidity, in general, decrease with increasing distance from the coast and are factors of great importance in determining the distribution of the fusca group.

Locality records for each species of the fusca group are listed according to the Province and nearest town or village to the place where they were collected, and the results are shown on maps. G. medicorum Aust. has only been recorded from the relatively dry northern part of the rain forest and forest islands or riverine forest in savannah in Western Nigeria. G. nashi Potts occurs in dense, wet rain forest in West Cameroun. G. tabaniformis Westw. occurs, especially, in forest reserves in Ondo and Benin Provinces of Western Nigeria and in wet rain forest in West Cameroun and adjoining forest country in Eastern Nigeria. G. haningtoni Newst. & Evans is common in wet rain forest in West Cameroun and there are also records 175 miles to the west in Delta Province of Western Nigeria. G. fusca occurs in a wider range of climatic conditions and habitat types than the other species; it has been recorded in vegetation varying from forest islands in savannah to wet rain forest. G. nigrofusca Newst. is a rare but widespread species in Nigeria and West Cameroun where it occurs typically in wet rain forest.

The dry and wet limits (indicated by mean annual rainfall) of the distribution of each species in Nigeria and West Cameroun are given, and the importance of climate, especially humidity, in determining these distributions is discussed. The climatic requirements of the six species are confirmed by their distribution outside the boundaries of Nigeria and West Cameroun. G. medicorum extends mainly to the west of Nigeria although there are also two records of the species from Gabon, widely separated from the main area of distribution of the species in West Africa. G. haningtoni and G. nashi, species typical of Central Africa (as here defined), extend only to the east and south of Nigeria (south in the sense of south of the latitude of Nigeria in territories in Central Africa). The remaining three species, those which occur in both reasonably dry and reasonably wet forest conditions in Nigeria and West Cameroun, extend both west and east and south of Nigeria and West Cameroun.

Some type of thicket or forest vegetation is the essential habitat for the survival of all six species of the fusca group. The main areas inhabited by the fusca group now are forest reserves in Western Nigeria and the relatively undisturbed forests of West Cameroun. The species are absent from much of southern Nigeria, and it seems certain that the increase of the human population over relatively recent times, and the effects that this increased density of population has had on the flora and fauna, has been the cause of the present-day discontinuous distribution of the fusca group in southern Nigeria. Man has an adverse effect on fusca-group tsetse populations through clearing of forest vegetation and the hunting and driving away of the game animals on which the flies depend for food. An inverse relationship between human population density and the number of records of the fusca group over southern Nigeria and West Cameroun is demonstrated.

The Makueni fly belt is chiefly infested with Glossina pallidipes Aust. and lies between 4,000 and 2,600 feet above sea level. The climate is hot and dry with two wet and two dry seasons, annually. The dry period during January and February is hot with bright sunlight while during the June to September dry period the temperatures are lower and with dull cloudy periods. The vegetation is Acacia-Commiphora dry grassland association with the Commiphora especially predominating at the lower altitudes in the east. The non-riverine deciduous bushland and thickets show two leafless periods in the year, corresponding with the dry seasons. A system of regular fly patrols has been in operation in this area since January 1949. The total flies caught show a regular seasonal increase during February-March each year and less regular and smaller increases during June-July and October-November. The same seasonal increases in the fly-populations are shown by the average number of old male flies caught per patrol.

Flies caught during 1951 were fewer than in 1950 in the settled areas and at Thwake camp, but at Kikumeni in the dense Commiphora-Acacia thickets the catches in 1951 were at least as numerous as in 1950.

Field experiments in England with traps baited with allylisothiocyanate (ANCS) showed that females of Delia radicum (L.) were distributed more or less evenly through established brassica crops. Reducing the quantity of ANCS released from the traps either by diluting the concentrate with liquid paraffin or by presenting the concentrate in Wädenswil dispensers reduced the numbers of females caught. There was no indication that ANCS became repellent, even when released at a rate of 24 ml/trap per day. For maximum effectiveness, the ANCS dispenser had to be placed at the centre rather than at the edge of the trap. Attempts to make traps more effective by releasing the ANCS from several point sources around a trap, in the hope that this broader odour plume would ‘ attract ’ more flies, were unsuccessful. The ANCS-baited trap had an effective zone only 5 m in radius.

As part of a programme to test the sterile insect technique against Glossina morsitans morsitans Westw. in Tanzania, two aerial applications of endosulfan were applied to a 195-km2 test area. The applications were made with a 28-day interval to provide an initial reduction in the target species prior to the release of sterile males. A Cessna 310 aircraft equipped with a rotary atomiser and operating at night was used to apply the insecticide at a dosage of about 20 g/ha. Flyround surveys within 48 h following the spraying operations indicated that a 100% reduction of G. m. morsitans adults was achieved in both applications, while G. pallidipes Aust. was reduced by 91 5% in the first and 100% in the second.

A laboratory colony of Stomoxys nigra Macq. was established in February 1976. Techniques were developed to produce 100 000 to 125 000 pupae daily in a larval room of 12 m2. The adults were fed on stored titrated blood and reared at a density of 500 pairs dn nylon cages with sides of 30 cm. The adult room was maintained at 29±1·5°C, 75–80 % RH and LD 14:10. To ensure a continuous supply of ovipositing individuals, 24 new cages with mature pupae were daily put in the adult room (capacity 280 cages) and an equal number of cages containing senile flies were removed. Eggs were harvested on moist khaki cloth below the adult cages, then concentrated in a trough of water and seeded at the rate of 1 ml (10 500 eggs) per kg of larval medium. The larval medium consisted of a mixture of 4 parts by weight of shredded sugar-cane (or elephant grass) leaves, 1 part soft Wheat bran and water at 2 ml/g dry matter. Larvae were reared in trays (45×35×7.5 cm) covered with cloth sacks to prevent invasion by pests. Eleven days after seeding, pupae were separated from the medium by flotation over water. From 2 September 1977 to 8 December 1977 forty trays, each yielding from 2000 to 3500 pupae, were harvested daily.

The deposits found on apples at various times after application of 11 insecticides were determined by chemical analysis of samples from an orchard in south-eastern England sprayed in 1959 and 1960. The results, from samples taken simultaneously, of studies of the effectiveness of these and other chemicals for control of the codling moth, Cydia pomonella (L.), have already been reported.

The period in which 50 per cent, of an initial deposit disappeared in the field (half-life) was calculated from the chemical data and used as a measure of persistence. For comparisons of intrinsic toxicity, the levels of fresh deposits causing 50 per cent, mortality of newly emerged codling-moth larvae (LD50) were determined in the laboratory by chemical and biological tests on apples dipped in a range of concentrations of commercial formulations. The LD50's, in μg./cm.2, were less than 0·025 for carbophenothion, parathion and diazinon, between 0·025 and 0·05 for azinphos-methyl and -ethyl, between 0·05 and 0·10 for malathion, DDT and carbaryl, between 0·1 and 0·5 for DDD and dimethoate, between 0·5 and 1·5 for lead arsenate and above 1·5 for phenkapton.

Chemicals with an LD50 exceeding about 0·1 μg./cm.2 were considered not worth further investigation as codling-moth larvicides. The LD90's of the remainder were found and were taken as the minimum deposits that would have an adequate effect from the standpoint of control (minimum effective levels). From the half-life values, the periods for which the deposits found in the orchard in 1960 should have remained above the minimum effective levels were calculated; these were 24 days for DDT emulsion, 22 for DDT wettable powder, 15 for carbophenothion, 14 for carbaryl, 12 for azinphos-ethyl, 11 for parathion, 7 for malathion and 6 for diazinon. They were in good agreement with the results of the biological tests except in the case of DDT emulsion, the effectiveness of which was unexpectedly short-lived.

The following report is the fifth and last of a series dealing with entomological research in the British Possessions in West Africa. The other four have appeared in previous issues of this Bulletin, and in them the aims and methods adopted have been stated in considerable detail. This paper deals mainly with the results of personal observations on the geographical distribution of the various blood-sucking insects in the Gold Coast, made during a tour in that country from November 1912 to June 1913; with these are incorporated, wherever possible, records of previous workers in this line, and consequently the report may be taken as a general summary of entomological work accomplished in this Colony.

The wings of male Glossina morsitans appear to become frayed in the rainy season at about the same rate as in the dry season, and their brittleness seems directly related to age. The law of diminishing returns does not appear to apply, perhaps because of the weakening of portions of the trailing edge between indentations fairly near together.

Oryzaephilus mercator and O. surinamensis are stored grains and processed food pests, the latter being responsible for major economical losses. Polyacrylamide gel electrophoresis was used to analyse esterase patterns during insect development. Seven esterases, three cholinesterases, two carboxylesterases and two acetylesterases, were identified in O. mercator, one of which was proper to adults. Five esterases, of which four were cholinesterases, occurred in O. surinamensis. Strains of O. mercator and O. surinamensis were also exposed to malathion and chlorpyrifos-methyl. According to the LC50 estimates, OmLC-M and OmLA strains of O. mercator and OsLB strain of O. surinamensis were the most resistant to both insecticides. However, higher sensitivity to malathion and chlorpyrifos-methyl has also been verified in some of its esterases. Cholinesterases OmEST-1 and OsEST-5 seem to be involved in this resistance. These results suggest that organophosphate tolerance may be related to genetic variability in esterase isoenzymes.

Wheat bulb fly (WBF) larvae use chemotaxis to orientate towards host-plant root exudates. This study aimed to investigate the role of the primary plant metabolite carbon dioxide (CO2) in host-plant location by WBF. Arena based behavioural experiments were used to identify whether CO2 induced chemotaxis (directional movement in response to a chemical stimulus) or kinesis (non-directional movement in response to a stimulus) from WBF larvae. No chemotactic response was observed when larvae were presented to a point source of CO2. However, elevated levels of CO2 induced kinesis, with both track length and tortuosity (number of twists and turns in the movement path) increasing at elevated CO2 levels of 1000–2000 ppm, demonstrating increased searching behaviour. Soil emission of CO2 was quantified to compare soil levels with those identified as eliciting behavioural effects on the larvae. Samples removed from soil gave a mean CO2 concentration of 557 (±46) ppm, which is lower than the lowest concentration of CO2 found to induce a behavioural response and higher than the lowest CO2 concentration tested, which was found not to alter behaviour. It is proposed that increased CO2 concentrations in the soil act as a behavioural trigger, inducing intensive searching of an area by WBF larvae. This increases the likelihood of finding more host-specific identifiers, such as secondary metabolites when near a potential host-plant.

Three highly repetitive DNA sequences Rp36, Rp217 and Rp234, have been isolated from Anopheles culicifacies Giles sensu lato. The cloned DNA sequences were found at a higher copy number in species B and C, than in species A of the A. culicifacies complex. These sequences may therefore be used as DNA probes to distinguish species A from the other two species, using a 200-fold dilution of a single mosquito DNA extract in a dot-blot hybridization assay. Rp36 and Rp217 have been completely sequenced. Internal repeats were absent in Rp36. Two related core sequences of 13 and 16 bp were found tandemly repeated in Rp217. These probes enable the rapid detection of species A of A. culicifacies in field investigations.

As time passes and knowledge accumulates, it becomes more and more difficult and tedious to know whether a certain insect has been recorded from a particular region or country. The present note is an attempt to save other people's time and to set down what is recorded about the geographical distribution of five species of flea, Xenopsylla cheopis, astia and brasiliensis, Nosopsyllus (Ceratophyllus) fasciatus and Pulex irritans.

The relationship was studied between susceptibility of a number of different species of insects to HCN fumigation and the recovery of HCN from them immediately after fumigation.

The test insects used were Tribolium castaneum, seventh stage caterpillars of Corcyra cephalonica, first-and second-instar nymphs of Drosicha sp., third-and fourthinstar nymphs of Drosicha sp. and adult females of Drosicha sp.

The apparatus and methods used in the fumigation and in the recovery of HCN from the fumigated insects are fully described.

Preliminary expsriments showed that the processes of distillation and redistillation did not affect the recovery of HCN but that the result obtained for recovery from distillation could be affected if some volatile reducing substance were produced and carried over to the distillate. It was found that this did actually take place in the case of one of the test insects—T. castaneum—but that redistillation got rid of the impurity.

In the main experiments it was shown that, on the assumption that the concentration of HCN to which insects are exposed is the effective dosage, the susceptibility of the test insects varied in the following descending order : firstand second-stage nymphs of Drosicha sp. > third- and fourth-stage nymphs of Drosicha sp.>C. cephalonica> T. castaneum>the adult females of Drosicha sp.

When the same insects were arranged in descending order of the quantities of HCN recovered per 100 gm. of body weight, the order was identical except for the nymphs of Drosicha sp. which occupied a different relative position. The two categories of nymphs of Drosicha sp. were found to occupy a different relative position again with regard to the other three test insects when exposed to a superlethal concentration and assessed for recovery of HCN per 100 gr. body weight.

Parallel batches of T. castaneum and C. cephalonica were fumigated and the HCN was recovered from the dead and survivors. More HCN was recovered from the dead insects than from those that survived.

Both recovery and sorption of HCN were estimated separately in parallel batches of insects (adult females of Drosicha sp. and C. cephalonica). Recovery was found to be less than sorption showing that a part of the HCN absorbed is converted into a non-recoverable state. Further, that the weight of HCN sorbed per gram body weight of adult females of Drosicha sp. is much less than in the case of C. cephalonica under similar conditions of fumigation and that the amount of HCN converted into non-recoverable products is less in Drosicha adults than in C. cephalonica.

A comparison of the water content of T. castaneum, C. cephalonica and Drosicha sp. (adults) showed that there was a positive correlation between water content and higher susceptibility to HCN and greater recovery of HCN was also indicated. It is suggested that this may be a factor in the “ Surface Resistance ” of an insec to a fumigant.

The observations of previous workers that larger amounts are sorbed by or recovered (after fumigation) from more susceptible species than for those less susceptible was corroborated by the results obtained with C. cephalonica, T. castaneum and adult females of Drosicha sp. but not with those from nymphs of Drosicha sp.

When dosage-mortality graphs were prepared by taking the amount of HCN recovered per gram body weight as an index of internal dose, the order of resistance of different test insects based on this new criterion was found to be entirely different from that based on the usual criterion of the concentration of HCN in the fumatorium being the index of effective dosage.

These apparently anomalous observations may be explained by assuming that the resistance shown by an insect in an actual fumigation operation, i.e., to the concentration of HCN to which it is exposed (external dose) is what may be called the total “ Effective Resistance ” and that this “ Effective Resistance ” is the resultant of (a) “ Surface Resistance ” to the entry of fumigant and (b) “ Internal Resistance ” to the amount of HCN which actually gains entry into the body in some way or other. Thus the “Effective Resistance ” of an insect may be due to a combination either of low “ Surface Resistance ” and high “ Internal Resistance ”, giving a very low “ Effective Resistance ” as in the case of C. cephalonica, or vice versa giving the maximum “ Effective Resistance ” as in adult females of Drosicha sp. The lower recovery of HCN from the nymphs of Drosicha sp., although they were more susceptible to fumigation than C. cephalonica, is explained by their higher “ Surface Resistance ” combined with a very much lower “ Internal Resistance ”, leading to a lower “ Effective Resistance ”.

Creontiades dilutus (green mirid) and C. pacificus (brown mirid) are major hemipteran pests of transgenic (Bt) cotton in Australia. Current integrated pest management (IPM) guidelines for mirids in Australian cotton, based on economic thresholds and sampling recommendations, were developed and disseminated to industry at the start of the 2005–06 growing season and have remained largely unchanged since then. However, adoption of mirid IPM guidelines by industry has been highly variable and generally well below expectation. Annual surveys of crop protection practices across the Australian cotton industry, from 2010 to 2017, indicate that a third of all mirid sprays are applied below the recommended thresholds each year. More than half of all survey respondents in the 2017 survey indicated lack of confidence in the mirid thresholds due to highly variable and disproportionate damage, a phenomenon best described as the ‘mirid enigma’. A critical review of RD&E outputs since 1998 shows that potential contributors to the mirid enigma include but are not limited to biological, ecological and methodological factors. Mirid feeding damage is likely to vary with developmental stage, gender and reproductive status. Ecological factors including trophic effects and multiple host plant usage are potential modifiers of mirid feeding damage. Methodological and technological constraints and shortcomings are evident in the threshold research done to date. Inadequate commercial sampling that results in unreliable estimates of pest density in the crop is a major contributor to the mirid enigma. Failure to account for the complexity of factors that can influence the nature and severity of mirid damage to cotton often results in fruit loss due to non-mirid related factors being incorrectly attributed to mirids. An alternative approach to mirid management based on modelling the dynamics of net fruit load (production–loss) proposed over 15 years ago is discussed.

The giant mealybug, Drosicha stebbingi, Green, which occurs in Northern and Central India, was described for the first time in 1900. Observations on its life-history and control have been made by Stebbing (1899–1903) at Dehra Dun, Lefroy (1908) and Dutt (1925) at Pusa, Richards & Sharma (1934) at Cawnpore, and Misra & Rao (1938) at Benares. Savage (1914) investigated the respiratory system of the female. Hingston (1929) made observations in Central India. Beeson (1941) has briefly recapitulated its life-history and control. Though it has thus been the subject of investigation by a number of workers since 1900, the information so far collected is far from complete. No effective control has yet been devised, for the existing methods of combating it are directed towards preventing the fertilised females from descending the trees and entering the soil to oviposit, and this is after the damage has been done. Its habits, which have an important bearing on its control, have not yet been fully studied, and the present investigations were, therefore, undertaken in 1938. The results are presented in this paper.

Dispensers made of different materials and loaded with the female sex pheromone, (Z)-7-tetradecenal, were field-tested for attractancy for males of Prays citri (Mill.) in Israel. Hollow fibres of low density polyethylene, low density polyethylene chips and natural rubber septa were better than hollow fibres of polypropylene, hollow fibres of a polypropylene-polyethylene mixture, solid fibres of low density polyethylene and PVC tubes. In other tests, funnels with wall angles of 60° were inferior to those with angles between 70 and 80°; polyester funnels were superior to polystyrene and polypropylene ones, which were better than those of PVC or opalin coated with aluminium foil. Kaolin or talcum powder dusted on the inside walls improved the efficiency of polypropylene funnels. The catches in traps consisting of several plastic funnels or tubes under a roof and with insecticide to prevent escape did not differ significantly from those in the sticky traps. A modified version of a new trap with a renewable sticky floor is described; this and the funnel traps are at present the most useful and practical for catching P. citri males.

In 1927, 1931, 1935 and 1937 the writer published four papers on the food-plants of Nigerian insects in this Bulletin (18, pt. 1; 22, pt. 2; 26, pt. 2; and 28, pt. 1). The present paper contains additional data obtained between April 1936 and October 1939.

An insectary method for rearing the cacao Mirids, Distantiella theobroma (Dist.) and Sahlbergella singularis Hagl., is described. Adults are caged, for oviposition, on cacao seedlings grown in baskets. When the eggs hatch, the nymphs are transferred to, and reared on, unripe pods suspended in ventilated glass cages.