The Tobacco Cricket, Brachytrupes membranaceus (Dru.), is a pest of young plants of tobacco, maize and other field and garden crops in Southern Rhodesia. During the period of investigations, 1949–52, it was found to be widely distributed in the Territory, the heaviest attacks occurring in areas of light sandy soil of granitic origin. All stages are nocturnal and each individual excavates and inhabits a permanent burrow in the soil, that of an adult averaging 50 to 80 cm. in depth. The burrow has an enlarged chamber in which the cricket lives and stores food.

There is one generation a year. Oviposition takes place in February and March, the average number of eggs per female, as shown by dissection, was 216. Incubation takes about 30 days and development of the young nymphs is at first rapid. From June to October, the period of dry and often scarce food, development is retarded but increases rapidly during the third and fourth (the last) nymphal stages in November. From November to May, when young and succulent food abounds, development is rapid. The adults start appearing early in December.

The eggs are laid in the burrows and the young nymphs on hatching crawl away from the parent burrow, in all directions, in search of suitable places in which to start digging. The mandibles are used to excavate the soil which is thrown outwards by the forelegs, and the mounds formed by the time the adult stage is reached may attain a height of as much as 30 cm. When an adult is evicted from its burrow, as soon as it finds a suitable place to dig, it will disappear within the space of a minute.

The burrows may be found in virgin land or in cultivated land, or along the borders of cultivated fields. The food consists of succulent or dry vegetable matter, according to the time of year, and is carried to and stored in chambers in the burrows. In the virgin veld it consists mainly of lush grasses, seedlings and root suckers of trees such as Brachystegia and Isoberlinia in the rainy season and of dried material of a similar nature during tha dry months. In cultivated land, tobacco, maize, field beans, garden vegetables, seedlings and young transplants are cut and stored.

Although the food is compacted in chambers in the burrows it has not been found in a mouldy or fermenting condition. It is thought that it is conditioned before storage, the more succulent material being allowed to wilt before being taken into the burrow and the dry material when softened by dew.

Glossina longipennis is a species of tsetse-fly of which very little is known beyond its general distribution. In Kenya Colony, it inhabits extensive areas of the sparsely populated districts in the north and east. It extends across the coastal hinterland and penetrates into Tanganyika, where it is found in the Pare-Usambara belt (Potts, 1937). The species also occurs in a somewhat isolated belt in the vicinity of the lower Southern Uaso Nyiro in the Masai Reserve and continues into the Sonjo-Natron fly-belt of Tanganyika Territory.

The durations for development for immature stages of the fruit piercing moth, Eudocima salaminia (Cramer), were determined at constant temperatures ranging from 15°C to 27°C and at ambient temperatures at a field site in southeastern Queensland over a 16 month period. At constant temperatures average heat requirements for: 50% eclosion of eggs were 62.4 day-degrees above 11°C, development of larvae to pupation were 246 day-degrees above 12°C, development of pupae to eclosion were 233 day-degrees above 12°C. For each stage there was no difference between day-degrees calculated at constant temperatures or at those in the field indicating no diapause in the immature stages. For adults, temperatures below 16°C during the activity period after dusk prevented feeding, mating and oviposition. Failure of E. salaminia to overwinter in south-eastern Australia in most years, was explained by the effects of low temperatures on egg hatch, larval, pupal and adult survival, reduced adult feeding, mating and cessation of oviposition.

Cassava (Manihot esculenta Crantz) is one of the most important staple crops for small farmers in the tropics, feeding about 800 million people worldwide. It is currently cultivated in South and Central America, Africa and Asia. The genus Vatiga is widespread throughout the Neotropical region. Its species are sympatric and feed exclusively on cassava. The main objectives of this paper are: (1) to assess the potential distribution of Vatiga, one of the most relevant pests of cassava; (2) to project the resulting models onto the world; (3) to recognize areas with suitable and optimal climates (and thus, high probability) for future colonization, and (4) to compare this model with the harvested area of cassava analyzing the climatic variables required by both the host and the pest species. Species distribution models were built using Maxent (v3.3.3k) with bioclimatic variables from the WorldClim database in 2.5 arc min resolution across the globe. Our model shows that Vatiga has the potential to expand its current distribution into other suitable areas, and could invade other regions where cassava is already cultivated, e.g., Central Africa and Asia. Considering the results and the high host specificity of Vatiga, its recent appearance in Réunion Island (Africa) poses a serious threat, as nearby areas are potentially suitable for invasion and could serve as dispersal routes enabling Vatiga to reach the continent. The present work may help prevention or early detection of Vatiga spp. in areas where cassava is grown.

(1) The history of Otiorrhynchus cribricollis in Australia is traced and records of its distribution in other countries are cited.

(2) Methods used in the experiments are described.

(3) The incubation period of the egg was found to vary between 14 and 37 days. The average was 22·3 days.

(4) The habits of the larva are described. Dyar's Law was applied to determine the number of instars, which was found to be 10.

(5) The normal duration of larval life is from May to October or a period of about 5 months.

(6) About 10 per cent. of the larvae aestivate through one summer. These have a larval life of about 17 months.

(7) Normal life of the adult is from November to April, about 5 months, but some (about 11 per cent.) hibernate through one winter and thus live 17 months.

(8) The adults feed in two seasonal periods separated by an interval of about 6 weeks, during which time they are inactive.

(9) The adults have been observed to feed upon 21 different plants, representing 12 different families.

(10) Most of the eggs are laid in the autumn, but a few are laid in the spring.

The silver fly Leucopis glyphinivora Tanasijtshuk (Diptera: Chamaemyiidae) is an aphidophagous predator during its larval stage. Our study describes the life cycle of L. glyphinivora and evaluates its potential as a biocontrol agent. The development, survival and longevity of L. glyphinivora were observed and compared with those of the aphid gall midge Aphidoletes aphidimyza Rondani (Diptera: Cecidomyiidae). Tests were conducted under laboratory conditions in Petri dishes with the green peach aphid Myzus persicae Sulzer (Hemiptera: Aphididae) on potato leaves. Leucopis glyphinivora has a 42% longer life cycle than A. aphidimyza. Larval development was 27% longer in L. glyphinivora than in A. aphidimyza. Egg hatch rate and pupal emergence rate were similar in both species, but larval survival was 20% lower for L. glyphinivora than for A. aphidimyza. Sex ratio was approximately 50% in both species. A longer development time for L. glyphinivora in the larval stage could be an advantage for biocontrol by providing more time to exert predation pressure against aphids. However, this may be offset by the lower survival rate found in the silver fly larvae.

1. When studying the effect of intermittent starvation upon the length of development of the larval phase it is necessary to carry out experiments with each stage separately. Ignoring this factor and carrying out experiments on the larval phase as a whole results in serious errors.

2. The shorter the periods of feeding and consequently the longer starvation periods during each 24 hours the stronger their effect upon the length of development of each stage.

3. More than 50 per cent. of larvae fed only for 2 hours a day and starved for 22 hours accomplish their complete metamorphosis and produce moths that are fully capable of living.

4. The length of development of each stage depends upon the feeding regime during the previous stage. Using the same starving regime, development of the last stage is the longer the earlier the stage at which larvae were subjected to this regime.

5. At different stages of development larvae react differently to the same starvation regime. Thus starving for 12 hours a day increases the duration of the development of the 3rd stage by 104 per cent. ; that of the 4th stage does not increase at all, while the development of the 5th stage increases only by 31 per cent.

6. Nature of food greatly influences the length of development under conditions of intermittent starvation. Starving for 8 hours a day when feeding larvae on wormwood results in greater increase of development than starving for 12 hours a day when feeding on goose-foot.

7. All factors influencing the development of the larval phase result in decreasing the weight of the pupae. Decrease in weight of pupae is the greater the longer the starvation periods and the earlier larvae were subjected to starvation effect. Nature of food also highly affects the weight of pupae.

8. Intensity of feeding during feeding periods of starving larvae does not decrease as compared to control. With very strongly starving larvae intensiveness of feeding even increases.

9. There is no direct proportion between the quantity of excrement passed, that is amount of food consumed and the weight of pupae. The longer the development, the more there are feeding periods and consequently the more excrement passed. Owing to the lengthening of development the most part of substances consumed are spent on vegetative functions ; therefore there cannot exist direct connection between the number of excrement passed and the weight of pupae.

The synthetic juvenile hormone analogue (S)-hydroprene can control populations of the oriental cockroach Blatta orientalis Linnaeus. Eradication of B. orientalis infestations, however, can take in excess of two years. In an attempt to reduce the time (S)-hydroprene takes to eliminate a population of oriental cockroaches, we explored the possibility of using the oothecal endoparasitoid Aprostocetus hagenowii Ratzeburg in combination with (S)-hydroprene. For such a strategy to be successful, it is important that the parasitoid remains substantially unaffected by (S)-hydroprene. When A. hagenowii was exposed to B. orientalis oothecae in the presence of (S)-hydroprene, female parasitoids showed no reduction in their capacity to attack hosts and their fecundity was not compromised. (S)-hydroprene, at dose rates of 18 mg/m2 and 100 mg/m2, induced deformity in approximately 12% and 33% respectively of parasitoids that emerged. No reduction in reproductive viability was seen in morphologically normal F1 parasitoids. Deformed F1 parasitoids, exposed to the higher (S)-hydroprene dose, showed a 71% reduction in the number of oothecae attacked and a 50% reduction in the number of offspring produced. These results indicate that A. hagenowii could be used in combination with (S)-hydroprene in an integrated pest management programme against B. orientalis.

Surveys of egg pods of agriculturally important grasshoppers were carried out in northern Benin between 1992 and 1995. Searches were made of oviposition sites under shrubs of the perennial legume Piliostigma thonningi along field margins. In 1993 and 1995, surveys were extended to include sorghum, Sorghum bicolor, and the perennial thatch grass Vetiveria nigritana. The four principal grasshopper species found at these oviposition sites were Hieroglyphus daganensis Krauss, Cataloipus fuscocoeruleipes Sjöstedt, Kraussaria angulifera (Krauss) and Tylotropidius gracilipes Brancsik comprising 86% of 4545 identified egg pods while 651 egg pods could not be identified to species level. Predation by meloid beetles (Epicauta, Mylabris and Psalydolytta spp.) varied between 0 and 50% for the four dominant grasshopper species. From 1993 and 1994 data, nymphal eclosion from egg pods damaged by meloids was significantly lower than emergence from undamaged egg pods. The hymenopterous parasitoids Scelio africanus Risbec and S. mauriticanus Risbec were reared from the four dominant grasshopper species and parasitism levels of 0.0–3.3% were recorded from these hosts. There were significant differences in nymphal emergences between parasitized and unparasitized egg pods of H. daganensis.

Cytochrome P450s (CYPs or P450s) have been long recognized as very important enzymes in the metabolism of xenobiotic and endogenous compounds, but only a few CYPs have been functionally characterized in insects. The effort in functional characterization of insect P450s is heavily hindered by technical difficulties in preparing active, individual P450 enzymes directly from the target insect. In this paper, we describe the functional expression of two additional pyrethroid resistance-associated CYP9A genes (CYP9A12 and CYP9A17) from the polyphagous pest Helicoverpa armigera in the facile Escherichia coli. The functionality of E. coli produced CYP9A12, CYP9A14, and CYP9A17 was investigated and activities of these CYP9As were compared against three probe substrates after reconstitution with NADPH-dependent cytochrome P450 reductase. The results showed that active forms of CYP9A12 and CYP9A17 were expressed in E. coli with a content of about 1.0–1.5 nmol mg−1 protein in membrane preparations. In vitro assays showed that CYP9A14 was capable of catalyzing O-dealkylation of methoxyresorufin (MROD), ethoxyresorufin (EROD), and benzyloxyresorufin (BROD), while CYP9A12 and CYP9A17 exhibited only MROD and EROD activities. Kinetic studies demonstrated that CYP9A14 had the greatest kcat/Km value for MROD, and CYP9A17 for EROD, while the lowest kcat/Km values for both MROD and EROD were observed for CYP9A12. The distinct biochemical traits suggest that the three paralogous CYP9As may play different roles in xenobiotic metabolism in this important pest.

Ecological, population and community studies of arthropod fauna inhabiting dung require large-scale quantitative data to produce statistically adequate results. A mechanized extraction technique is described which recovers fauna accurately and rapidly from large numbers of cattle dung pads. The equipment comprises a motor-driven paddle which agitates the dung sample in a bucket with fine mesh panels inlaid into its walls and through which is passed a continuous flow of water. An electric motor drives five such units simultaneously. Most dipteran puparia and adult arthropods float on water and are recovered following the washing. Puparia are recovered manually, while mites and adult beetles are extracted from the floating debris with heat in modified Berlese-Tullgren funnels. The wash bucket and its drained contents are then immersed in a flotation vat through which a sodium carbonate solution is recirculated. Insect eggs and larvae are floated off into sieves and rinsed before preservation. The resulting samples are fixed and preserved in 70% ethanol for later identification and counting. The procedure recovered 70–90% of most types and stages of dung fauna. Up to 25 complete dung pads can be processed per day with a team of three people.

Groups of Coptotermes acinaciformis (Froggatt) originating from six colonies, three taken from each of two widely separated localities in northern Australia (Townsville and Darwin), were kept at population densities of 0·005, 0·001 or 0·020 g termites/ml. Survival and wood consumption of the groups after eight weeks followed a similar pattern in the colonies from both collection areas. Groups exhibited least vigour at the lowest population density, most vigour at the middle density and slightly less than maximum vigour at the highest density. However, the actual values for survival and wood consumption varied widely between colonies, irrespective of their origin. The implications of these and related results for laboratory experiments which rely on survival and wood consumption as indicators of termite vigour are discussed.

The pupa is bilaterally symmetrical, that is, setae occur in similar situations on each side of the body, so that it will suffice to describe the arrangement on one side only. The setae on the two sides of the same pupa, however, often vary as regards their sub-divisions, and similar variations occur between different individuals; as an example, in Table I are shown some of the variations that were found in ten pupae taken at random. An examination of a larger number would have revealed a wider range. As a rule, a seta which is sometimes single, sometimes divided, is longer when single. For example, in one pupa the seta at the posterior angle of

the seventh segment was single on the right side, double on the left; the former measuring 266μ, and the latter only 159μ in length. This fact is not specifically mentioned in the descriptions which follow, but should be understood.

Monophlebus stebbingi, Green, var. octocaudata, Green, is a large Coccid belonging to the sub-family Monophlebinae. It is found on Mango, Jack Fruit, and species of Ficus, in India, but having, for a Coccid, a long life-history—being but single-brooded—it is rarely a pest. Climatic conditions govern the production of large numbers of individuals, so that outbreaks are irregular, occurring at intervals of a few years.

In insecticide trials in Southern Rhodesia against the woolly apple aphid, Eriosoma lanigerum (Hsm.), using methyl-demeton (0·078 and 0·052 per cent. active ingredient), dimethoate (0·0625 and 0·0417 per cent. active ingredient), diazinon (0·0625 per cent. active ingredient) and malathion (0·1041 per cent. active ingredient) as foliar sprays, all insecticides gave good control of infestations above ground, but methyl-demeton and diazinon gave the best control, and treatments were followed by slower rates of repopulation.

Injecting the lower part of the trunks of trees 25 to 30 years old with ½ fluid ounce of a concentrate of a systemic insecticide, 50 per cent. methyl-demeton or 40 per cent. dimethoate, at a single point gave excellent control where that part of the sap stream supplying the aphid colonies was intercepted. By injecting with a spiral of small holes around the trunk using ½ fl. oz. 50 per cent. methyl-demeton, control of all aphids on the tree could generally be achieved.

Good control of subterranean aphid colonies on 15-year-old trees was achieved by the application to the soil of 4 gal. per tree of a fluid containing 100 cc. of a concentrate containing 75 per cent. of V-C 13 (O,O-diethyl O-2,4-dichlorophenyl phosphorothioate) diluted with water.

Biological control of E. lanigerum in Southern Rhodesia by the Hymenopterous parasite Aphelinus mali (Hald.), which was introduced in 1961, shows great promise.

Aëdes argenteus, Poiret, is a very variable mosquito, and it was thought that it would be interesting to examine a number of freshly-hatched and therefore undamaged specimens and to note how many conformed to the original description. No difficulty was experienced in obtaining the necessary material, as collections of larvae are received daily from the Medical Officer of Health. One thousand of each sex of the species were mounted in the order of their emergence from the pupal case and were examined under the binocular microscope. The one constant feature was found to be the lyre-shaped marking on the thorax, although even here the outline and the centre lines varied in breadth and in colour, and the centre lines varied in length. But as the abdomen and the hind tarsus showed the greatest variations, the present paper is restricted to a description of these.

The genus Stenobracon Szépligeti which contains species of economic importance for biological control of lepidopterous borers of sugarcane, rice and other graminaceous crops in Asia, is revised. Principal components analysis was employed to help delineate species. Six species, distributed from Pakistan to Australia, are recognized. Stenobracon brevis, S. clarus and S. malensis are described as new and Stenobracon nicevillei (Bingham), S. deesae (Cameron) and S. oculatus Szépligeti are redescribed. Illustrated keys for males and females are provided. Phanaulax levituberculatus Cameron is a new junior subjective synonym of S. nicevillei and S. trifasciatus Szépligeti is a new junior subjective synonym of S. oculatus. Elphea flavomaculata Cameron is synonymized with Ischnobracon (Bracon) laboriosus Cameron (comb. n). Host records are summarized.

Eurytoma verbena, sp. n.

♀♂. Black ; abdomen sometimes a little reddish on the sides. Antennae dark brown ; pedicel slightly yellow below. Wings whitish, with the veins very clear yellow. Legs with coxae and femora black, the latter sometimes a little reddish ; tibiae red in the middle, often mixed with black, especially at the hind tibiae ; knees, base and tip of tibiae, and the tarsi whitish.

♀. Head rugulose, face covered with white ciliae, with a carina between the base of antennae and the clypeus, and weaker striae diverging from the mouth. Antennal furrow rather deep, bordered by a carina and reaching almost to the median ocellus. Cheeks as long as half the length of the eyes, finely rugulose. Antennae inserted in the middle of the face ; scape short, reaching very little beyond the top of the antennal furrow ; pedicel not longer than broad ; annelli very small ; funicle joints longer than broad, the 1st almost twice, the 2nd about 1·5 times longer than broad, the following gradually shorter.

Thorax more strongly sculptured than the head, reticulate. Scutellum protruding a little above the postscutellum, which is hidden, and the propodeon ; this latter, seen from the side, has the posterior margin almost vertical. Mesopleurae finely punctate, with some short horizontal striae ; episternum transversely striate, but the striae not reaching to the hind margin, along which it is punctate, like the mesopleurae.

An investigation into the seasonal abundance of Zonocerus variegatus (L.) around Ibadan, Nigeria, showed that hatching occurs between October and March and peak abundance is in late November. Adults occur almost throughout the year. Oviposition takes place between March and October or possibly November, with a peak in April. Eggs laid in March and April hatch in October and November after a diapause, while those laid from June onwards do not appear to enter diapause. Thus eggs laid in June and July hatch at the same time as those laid in March and April. Parasitism by the sargophagid fly Blaesoxipha filipjevi (Rod.) during March and April results in a rapid decline in adult numbers which may be followed by a secondary peak in adult numbers when nymphs, which are present at the same time and are rarely parasitised, reach adult stage. Oviposition resulting from such a peak does not produce a secondary peak in hatching as this coincides with hatching from earlier layings. The fungus Entomophthora grylli plays an important role in controlling the abundance of nymphs and adults during the dry season despite the intermittent nature of the attacks. During the wet season, the fungus is able to germinate and disperse more readily, thus keeping the numbers of the insects low. It is concluded that there is one generation of Z. variegatus a year, with a peak in population coinciding with the dry season (November-March). It is suggested from the results that the grasshopper may have originated in the semi-arid zones of the north.

Culex pipiens Linnaeus is represented by two forms: the form molestus which is autogenous, stenagamous and has no reproductive diapause, and the form pipiens which is anautogenous, eurygamous and diapauses. The ecological, physiological and geographical variations in the larval siphonal index of C. pipiens (the ratio of the length of the siphon to its width at the base) was investigated using both original measurements and previously published data. In all, data were used from 259 collections from open water bodies (marshes, ditches, holes, barrels, etc.) and underground waters (house basements) in areas of Europe, Asia and part of Africa. Autogeny was studied in some cases by dissection of females. In C. pipiens the mean siphonal index was strongly correlated with ecology (water body type) and adult physiology (autogeny). In spite of high geographical and individual variation, which makes the identification of individual larvae difficult, the mean siphonal index can be used with certainty for the differentiation of populations of the two forms of C. pipiens.