An experimental laboratory study of the deposition of droplets on dead house-flies (Musca domestica L.) was made, using a spinning-top sprayer to produce a spray of uniformly sized oil droplets and a cascade impactor to measure the concentration of the spray of droplets, which were dyed. The deposits obtained on a dead house-fly and a cascade-impactor slide when these were exposed in turn to a wind of 1 m. per sec. in a wind tunnel were compared colorimetrically, and determinations thus made of the collection efficiency of the flies, defined as the volume of liquid deposited on an object expressed as a percentage of the volume that would have passed through the same cross-section as the object had that not been there.

The measured collecting efficiency of a fly varied from about 70 per cent. (droplet dia. 27μ) to about 200 per cent. (droplet dia. 75μ), and was approximately twice that of a sphere with a cross-sectional area twice the projected frontal area of the fly. From theoretical calculations of the filtering effect of different elements of the vegetation, it is concluded that the optimum droplet diameter for deposition on flies in woodland is 20–40μ.

The presence in Southern Nigeria of a well defined group of mosquitos whose breeding is confined to holes in trees has been known for some time, and Dalziel (1920) recorded a number of such species from Lagos.

In order to follow the changes appertaining to the post-embryonic development of the larva of the Indian lac-insect of the genus Laccifer a knowledge of its external

and internal anatomy was a desideratum. A study of its external and internal anatomy was, therefore, undertaken in order to obtain a knowledge of its organography, and the following account is based on the results of such a study.

An apparatus for dispensing the eggs of cabbage root fly (Erioischia brassicae (Bch.)) is described. It consists of an ‘Agla’ micrometer syringe, a 2-ml pipette and a 20-mlsyringe connected together by a three-way valve. The eggs are dispensed volumetrically, the standard errors being < ±10% for batches ranging from 30 to 300 eggs. This degree of variation had no measurable effects on the uniformity of pupae from cabbage root fly cultures.

The following data have been gathered over a period of about one year (January to December 1929) in the Nairobi District, Kenya Colony.

It was thought that the organic content of natural waters would certainly offer some indication of their suitability for the breeding of Anopheline mosquitos and that an investigation might suggest some definite line of approach to this intensely complex problem.

During November and December 1928, certain water sources were selected by one of us (C. B. S.), in widely separated parts of the district, for weekly sampling. In each separate area some four to eight places were chosen for routine searches for Anopheline larvae ; thus in the Q area (Table II) seven places were searched every week and in the B area (Table I) six places. From the places in each area two were chosen for routine oxygen absorption tests, one with Anopheline larvae and one without, water from these same two places being sampled and tested weekly. Thus in the Q area, spots Q 5 and Q 6 were used for this purpose, and in the B area B 3 and B 5. It is necessary to emphasise the fact that these places were separated from one another by distances of 50 to 150 yards. The choice of the source of water to be sampled was made purely on the presence or absence of Anopheline larvae at the beginning of the work.

A description is given of the damage caused by the larvae of two weevils, Systates exaptus Mshl. and Mesoleurus dentipes (Mshl.), which are soil pests of germinating maize and other crops in Rhodesia. Information is given on their life-cycles and some features of their biology. The larvae are nearly full grown at the beginning of the dry season, which is passed in an inactive state in the soil. Activity is resumed with the onset of the main rains, and it is at this time that the larvae may cause serious damage by attacking seedlings of maize or other crops growing in infested soil. Factors that encourage local increase of field populations are examined. It is shown that sunn hemp, soya bean and groundnut, all crops with high plant populations, favour the presence of large numbers of weevil larvae in the soil at the beginning of the following season. Growing closely planted maize year after year on the same land has been found to be one of the main causes of serious infestations in farm fields.

Results of soil-insecticide trials are given, and these show that larvae are very difficult to control. In the discussion, attention is drawn to similar weevil larvae indigenous to other parts of Africa, which are tolerant of soil insecticides and are also pests under conditions of intensive crop production.

Ways are suggested for reducing infestation in the following season. It is shown that properly timed applications of DDT to the maize crop will kill adults and prevent oviposition. Otherwise, infested fields may be left fallow, planted to grass or planted very late in the season.

No method of protecting germinating seedlings has been found, but reference is made to a soil-sampling technique that is useful for detecting infested fields before crops are planted.

The following Coccid was first recorded as a probable new species of Saissetia by Dr. W. J. Hall in Nutman and Sheffield (1949, p. 437), who suggested that it might be regarded as a possible vector, should a virus be the cause of Suddendeath disease of cloves. Although further research has shown that this disease is not caused by a virus, the species is of particular interest in its relationship with ants and this has been the subject of a special study by M. J. Way (in press).

Details of the insect and mite infestation encountered on food commodities imported into Britain from the United States of America between 1953 and 1961 are given. Twenty-eight species of insects and nine species of mites, thought to have been introduced with the goods are listed together with a further 35 species of insects thought to have been derived from ships' holds. Emphasis is laid on the dangers of foodstuffs acquiring infestation either by cross-infestation or from infested residues in the holds.

(1) Asterolecanium coffeae occurs in all the British East African Dependencies and has been the cause of much loss in certain low-lying coffee areas of Kenya. On the crop-bearing parts of the coffee tree (Coffea arabica) it inflicts injuries of an irreparable nature, and a heavy infestation is extremely difficult to eradicate.

(2) A. coffeae is oviparous, and after deposition the eggs pass through a period of incubation within the “ test ” of the mother. The fecundity of the female is low compared with that of the common Lecaniine scales and mealybugs which infest coffee in Kenya. The average number of eggs produced by a single female is about 50. The male is extremely rare and fertilisation of the female must be a very infrequent occurrence.

(3) The duration of development of the female from egg to egg varies between 60 and 70 days. The duration of the first stadium varies from 7 to 12 days, and that of the second stadium from 18 to 25 days. The pre-oviposition period is 28 days.

(4) The various stages of the female scale are described.

(5) Only one primary parasite of A. coffeae was obtained, namely, Metaphycus lounsburyi, How., and it is frequently abundant towards the close of the dry season, but its effectiveness is nearly always considerably reduced, by the high prevalence of a secondary parasite, Perissopterus busckii, How. A Coccinellid, Chilocorus angolensis, Crotch, preys upon the mobile first instar forms.

(6) A. coffeae is not a honeydew secreting Coccid and is entirely ignored by ants.

An account is given detailing some aspects of the biology and economic importance of Psalydolytta pilipes Maklin in pearl millet (Pennisetum glaucum) fields in north-west Mali. Descriptions of the triungulin larval stage, together with drawings of larval development from the first grub stage to the coarctate larval stage, are given for two Psalydolytta species, P. pilipes and P. vestita Dufour. First grub phase larvae were successfully reared through to coarctates from eggs obtained from field captured adult beetles, on egg-pods obtained from a selection of commonly occurring grasshopper species. Yield losses resulting from cage trial experiments showed that whole millet candles can be destroyed during one night's feeding at densities approaching 12 beetles per head.

Several artificial media were tested in an attempt to eliminate the use of human faeces as oviposition and early larval habitats for breeding Musca sorbens Wied. in the laboratory. Eggs, laid on cotton-wool pads moistened with diluted milk or, preferably, on small quantities (10–15 g.) of human excrement, were transferred to the breeding medium. The best of those tested was a mixture of coarse wheat bran (120 g.) and diluted milk (240 g.), which yielded normal healthy larvae and adults. The average weight of a puparium produced in this medium was somewhat less than that of one produced in human excrement.

Similar increases in the height and aerial fresh weight of cowpeas compared with control plants were obtained when plants were sprayed with either 50 ppm a.i. (active ingredient) of the pyrethroid insecticide ‘Cymbush’® containing cypermethrin, or, the equivalent dilution of a blank formulation without the a.i. With broad beans, similar growth stimulation was obtained with the blank at the same or half dose, but not at a quarter dose. Testing the four formulation components separately showed that only the non-ionic emulsifier caused stimulation. A comparison of the stimulation of plant growth by the blank and the non-ionic emulsifier showed that plant height, shoot fresh weight, leaf fresh weight, leaf dry weight and leaf area were each equally increased by both treatments. The non-ionic emulsifier thus accounted for the entire stimulation caused by blank solution. Populations of Aphis fabae Scopoli (Homoptera: Aphididae) were twice as high on broad bean plants sprayed with the non-ionic emulsifier as on the controls. ‘Cymbush’ (the complete formulation) sprayed at 25 ppm a.i. was shown to increase the intrinsic rate of natural increase of the aphid through a 22% increase in fecundity; aphid development time was not affected. The results do, however, suggest that residual effects of cypermethrin may have partly counteracted the stimulatory effects of the non-ionic emulsifier. Nevertheless, it is possible that outbreaks of aphids and mites following pyrethroid application, and often assumed without evidence to have been due to natural enemy mortality, may at least in part reflect the plant stimulation caused by the non-ionic emulsifier in the formulation.

The association between insects and virus diseases of plants and the suspicion which at present rests on Jassidae, amongst others, may result in members of this family becoming of increased importance as potential vectors of virus diseases of crop plants. In America leaf-hoppers are already serious pests of cereals and of grape-vines, and in the cotton-growing area of Central and South Africa a Jassid forms one of the most important obstacles to the successful cultivation of this crop, so that in these countries a considerable amount of attention has been demanded by this group of insects. In this country, however, the leaf-hoppers have only been regarded as of minor importance, though in recent years increasing interest has been taken in certain species infesting potatoes and glasshouse crops. It was suggested to the writer that further knowledge of the biology of these insects was desirable, especially in view of the extreme importance of a nearly related species in many of the African cotton-growing areas, and it was accordingly decided to use the common species infesting glass-houses as a type for investigation with cotton as the food-plant.

The vector role of Aedes aegypti for viral diseases including dengue and dengue hemorrhagic fever makes it imperative for its proper control. Despite various adopted control strategies, genetic control measures have been recently focused against this vector. CRISPR Cas9 system is a recent and most efficient gene editing tool to target the sex determination pathway genes in Ae. aegypti. In the present study, CRISPR Cas9 system was used to knockout Ae. aegypti doublesex (Aaedsx) and Ae. aegypti sexlethal (AaeSxl) genes in Ae. aegypti embryos. The injection mixes with Cas9 protein (333 ng ul−1) and gRNAs (each at 100 ng ul−1) were injected into eggs. Injected eggs were allowed to hatch at 26 ± 1°C, 60 ± 10% RH. The survival and mortality rate was recorded in knockout Aaedsx and AaeSxl. The results revealed that knockout produced low survival and high mortality. A significant percentage of eggs (38.33%) did not hatch as compared to control groups (P value 0.00). Highest larval mortality (11.66%) was found in the knockout of Aaedsx female isoform, whereas, the emergence of only male adults also showed that the knockout of Aaedsx (female isoform) does not produce male lethality. The survival (3.33%) of knockout for AaeSxl eggs to the normal adults suggested further study to investigate AaeSxl as an efficient upstream of Aaedsx to target for sex transformation in Ae. aegypti mosquitoes.

Juvenile hormone (JH) plays a pivotal role in almost every aspect of insect development and reproduction. The chemical structure of the JH in heteropteran species has long remained elusive until methyl (2R,3S,10R)-2,3;10,11-bisepoxyfarnesoate, commonly named as juvenile hormone III skipped bisepoxide (JHSB3), was isolated from Plautia stali (Hemiptera: Heteroptera: Pentatomidae). Recently, several groups reported the presence of JHSB3 in other heteropteran species. However, most of the studies paid no attention to the determination of the relative and absolute structure of the JH. In this study, we investigated the JH of the cabbage bug Eurydema rugosa (Hemiptera: Heteroptera: Pentatomidae), known as a pest for wild and cultivated crucifers. JHSB3 was detected in the hexane extract from the corpus allatum (CA) product using a chiral ultraperformance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) which can inform the absolute stereochemistry of the JH. Its stereoisomers were not detected. Topical application of the synthetic JHSB3 to the last instar nymphs inhibited their metamorphosis and induced nymphal-type colouration of the dorsal abdomen in a dose-dependent manner. Additionally, the topical application of JHSB3 effectively terminated summer and winter diapauses in females. These results indicate that the JH of E. rugosa is JHSB3. Although individuals in summer and winter diapauses are physiologically distinct in E. rugosa, the results suggest that the physiological differences between these diapauses are based, not on the responsiveness to JH, but on the processes governing activation of the CA or on its upstream cascades.

Mosquito-borne diseases have emerged in North Borneo in Malaysia due to rapid changes in the forest landscape, and mosquito surveillance is key to understanding disease transmission. However, surveillance programmes involving sampling and taxonomic identification require well-trained personnel, are time-consuming and labour-intensive. In this study, we aim to use a deep leaning model (DL) to develop an application capable of automatically detecting mosquito vectors collected from urban and suburban areas in North Borneo, Malaysia. Specifically, a DL model called MobileNetV2 was developed using a total of 4880 images of Aedes aegypti, Aedes albopictus and Culex quinquefasciatus mosquitoes, which are widely distributed in Malaysia. More importantly, the model was deployed as an application that can be used in the field. The model was fine-tuned with hyperparameters of learning rate 0.0001, 0.0005, 0.001, 0.01 and the performance of the model was tested for accuracy, precision, recall and F1 score. Inference time was also considered during development to assess the feasibility of the model as an app in the real world. The model showed an accuracy of at least 97%, a precision of 96% and a recall of 97% on the test set. When used as an app in the field to detect mosquitoes with the elements of different background environments, the model was able to achieve an accuracy of 76% with an inference time of 47.33 ms. Our result demonstrates the practicality of computer vision and DL in the real world of vector and pest surveillance programmes. In the future, more image data and robust DL architecture can be explored to improve the prediction result.

(1) The proprietary emulsion “Guesapon ”, containing 5 per cent. DDT, gave an unsatisfactory control of carrot fly damage on a plot scale.

(2) Treatment of the carrot foliage with this emulsion was more effective than treatment of the soil.

(3) A I per cent. emulsion of DDT applied to carrot foliage in the field gave 100 per cent. mortality of carrot flies in the laboratory for 26 days after treatment and showed marked toxicity after a further 38 days.

(4) The DDT spray deposits were very, resistant to treatment with water and remained active after death of the foliage. They were also very toxic and lasting on potato foliage.

(5) Deposits given by ½ per cent. and I per cent. DDT emulsion were similar in toxicity and persistence. The ½ per cent. is, however, slower in action.

(6) From a treated surface the carrot fly is able to acquire a lethal dose of DDT in a very short time, probably by absorption through the feet.

(7) Emulsions containing ½ per cent. and I per cent. DDT applied to carrot foliage under cages in the field both gave 95 per cent. kill of carrot flies for a month after application. The treatments also gave a high kill of other insects.

(8) Soil samples showed that the larval population and the damage was much lower in the treated than in untreated cages.

(9) In a field trial 2⅓ acres of carrots were treated with ½ per cent. DDT emulsion at about 50 gals. an acre.

(10) Sweeping showed a rapid decline in abundance of flies after treatment and high mortalities were observed. These features did not occur on neighbouring untreated carrots.

(11) These effects lasted for some 21 days after treatment and a marked reduction of larval population and damage resulted.

In a sub-tropical city like Cairo it is most important that, so far as possible, the main streets be protected from the direct rays of a powerful sun by numerous and healthy shade-giving trees. For this purpose, the Lebbek (Albizzia lebbek) has been very extensively employed in Cairo, where it affords a welcome shade, as well as adding very considerably to the appearance of the streets. Until the summer of 1909, these trees have, on the whole, filled their parts quite satisfactorily. They had only one serious insect enemy to contend against, in the form of a longicorn beetle—Xystrocera globosa, Oliv. Hitherto this “borer” has been considered by far the most important pest of the lebbek, since its attacks, although comparatively slow in their effects on the life of the tree, are yet sure, and when extended over a period of years have caused no little mortality amongst the shade-trees of this city. During the past year the importance of this beetle has been, so far as Cairo is concerned, somewhat eclipsed by the depredations of a comparatively new pest—a mealy bug. This insect proves to be new to science, and is described for the first time in the appendix to this paper under the name of Dactylopius pertiiciosus, sp. n.