Through the kindness of Prof. Mazza, Buenos Aires, Dr. P. A. Buxton, of the London School of Tropical Medicine, and Prof. Brumpt, Paris, I have had the opportunity of examining a collection of sandflies from South America. It appears that, as in the sandflies of the Old World, the structure of the buccal cavity and spermatheca, and to a smaller degree that of the pharynx, affords an easy mean of distinguishing the five species at my disposal.

(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.

A strain of Cryptolestes ferrugineus (Stephens) bred for malathion-specific resistance was found to be 650 fold resistant at LD50 when compared with a susceptible strain bred from the same stock. Resistance was more than 98% synergized by triphenyl phosphate and S,S,S-tributyl phosphorotrithioate, but unaffected by piperonyl butoxide. AChE inhibition by malaoxon varied slightly between the strains. Non-specific esterase activity as measured by the hydrolysis of α-naphthyl acetate was slightly reduced in the resistant strain whereas there were no inter-strain differences in the hydrolysis of β-naphthyl acetate. Products of in vitro metabolism of malathion were identified by thin-layer chromatography and gas chromatography-mass spectrometry as α- and β-malathion mono-acids. It was therefore concluded that resistance was due to the hydrolytic breakdown of malathion by a malathion-specific carboxylesterase. The rate of in vitro malathion hydrolysis was found to be 31 times greater in the resistant strain. In vitro inhibition studies indicated that resistance is attributable to a carboxylesterase unique to the resistant strain. The implications of these results are discussed in relation to work recently carried out on malathion-specific resistance in dipterous species.

Hylurdrectonus araucariae Schedl is a major pest in hoop pine (Araucaria cunninghamii) plantations at Bulolo and Wau in Papua New Guinea, establishing itself in nests inside the branchlets. The length of the excavation is proportional to the age of the nest. Colour changes in infested branchlets reflect changes in colony composition and in excavation activity as the colony ages; the branchlet eventually dies and falls off and severely infested trees lose much of their foliage. Data from field observations between 1967 and 1972 show that there are 5–10 overlapping generations of H. araucariae in a year. The life-cycle takes place wholly within the branchlet, except for a brief period of flight or walking by the adult when seeking new nesting sites. The eggs incubate for 5–15 days, larvae take 10–25 days, pupae 10–15 days, and the immature adult 2–10 days; the adult may live 60 days or more. The colony composition is fairly stable in heavily infested areas throughout the year, except during drought. Colony composition and size vary from branchlet to branchlet or from tree to tree, but are more similar on trees with a similar stage of infestation. No significant natural enemies were found.

The role of photoperiod in controlling the termination of adult diapause in the Bombay locust, Nomadacris succincta Linnaeus (formerly Patanga succincta) was examined by exposing pairs of field-collected adults to different photoperiods at 30°C. Adults of this species appear in June and remain in diapause until March in the following spring. Female adults collected in November started laying eggs earlier at a 14 h photoperiod (L:D 14:10) than at a 12 h photoperiod (L:D 12:12), although the mean pre-ovipositional periods at the two photoperiods were not significantly different from each other. All first egg-pods produced by long-day females contained fertilized eggs while only some short-day pairs produced fertilized eggs in their first pod, indicating that mating was suppressed at a short photoperiod. In adults collected in January and exposed to a 10 h photoperiod (L:D 10:14), the mean time of first oviposition was significantly delayed compared to those exposed to a 14 h photoperiod. These results demonstrate that N. succincta uses daylength as a cue to control the time of diapause termination in the field. The time interval between the first and second egg-pod depositions was influenced not only by the physiological state of the females but also by the environmental conditions, i.e. photoperiod, and it was positively correlated with the length of pre-ovipositional period. The occurrence of a change in host preference by diapause adults and its ecological significance were also pointed out.

Although Culiseta morsitans (Theobald) is a common Holarctic mosquito very little is known about its biology so many aspects of its life-history were studied, mainly in southern England, from 1964–1987. More limited observations were made in the south on the coastal Culiseta litorea (Shute). Both species laid an average of 109 eggs as an egg raft deposited on wet mud and leaf litter. At high humidities C. morsitans eggs can remain unhatched and viable for many months. Populations of both species overwinter as fourth instar larvae, pupation occurs in April and adults start emerging in early May. The adult season lasts until September or October. Both species feed principally on birds. Serological tests, however, on blood-engorged females show that a few feed on humans, although none has been caught in human bait collections. Light-traps are not very effective in sampling adults, although a few were caught in them, as they were in non-attractant suction traps. The relative sizes of adult populations of both species were monitored in most years from 1964–1980 on Brownsea Island, Poole Harbour, England, and showed a marked decline in the proportions of C. litorea, but there was a resurgence of this species after eight years, when the population again crashed.

Aedes aegypti (L.) (Diptera: Culicidae) is one of the main vectors of arboviruses, including dengue, Zika, and chikungunya. It almost exclusively inhabits urban areas. Both sexes feed on plant carbohydrates, although for males, this is their only food source. In the case of floral nectars, mosquitoes locate plant sugar sources assisted by volatile compounds. In this work, we found that the floral scent of Senecio madagascariensis elicited a behavioral response in males; therefore, we focused on identifying the volatiles emitted by these flowers. The terpenes (±)-α-pinene, β-pinene, sabinene, and phellandrene and 1-alkenes 1-undecene, and 1-nonene were identified. To determine which compounds are bioactive, pure synthetic lures were assessed using an olfactometer. Only the main compound 1-nonene was an attractant for males. Since our goal was the introduction of synthetic floral-based attractants in toxic sugar-baited traps, we formulated 1-nonene in solid paraffin and stearin matrices to obtain a controlled release system. The bioassay with a toxicological end point showed that the incorporation of a feeding attractant to the toxic sugar trap increased overall mortality. These results suggest that it is possible to use plant volatile compounds or flower cuttings as male Ae. aegypti attractants to improve the efficacy of baited traps.

The present paper reports the principal results from a survey undertaken with the objects of ascertaining the extent of the natural breeding areas of the red bollworm in South Africa and whether the habitats of the food-plants are well defined ecologically. It has been known for some years that the red bollworm feeds on wild cotton, Gossypium herbaceum, and on Cienfuegosia Hildebrandtii (Parsons), but from increased knowledge of the topography and vegetation of the country there were reasons to suppose that the distribution of these food-plants is quite considerably limited in the present and potential cotton-growing areas, and it was desirable that the situation should be investigated in some detail.

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 four components of the synthesised sex pheromone of Diparopsis castanea Hmps. are dodecan-1-yl acetate (I); trans-9-dodecen-1-yl acetate (IIA); 11-dodecen-l-yl acetate (IIB); and trans-9,ll-dodecadien-l-yl acetate (IV). Increasing the proportion of IIA in a I/IIA/IIB/IV mixture progressively decreased male excitation in a laboratory bioassay, whilst in the absence of I all concentrations of IIA tested were equally inhibitory. The synthetic combination of 80% IV (93% trans: 7% cis) and 20% IIB (=dicastalure), was 485 times more potent in eliciting male activity than a female sex pheromone gland extract. Reduction in male response to crude extract occurred through exposure of males to glandular IIA and through reduced pheromone volatility caused by extracted triglycerides. Maximum quantities of pheromone were detected in the female sex pheromone gland 6–12 h into scotophase and for at least 30 min into photophase. Significantly greater bioassay responses were elicited by the optimal field combination of 80% IV and 20% IIB than for other ratios tested. Excitation and clasper extension were observed in response to the non-attractive IIB moiety and this indicates a role in close-range mating behaviour for this component. The threshold level of male response was estimated to occur in response to sex pheromone at an aerial concentration of 9·2 molecules IV mm3/s−1. This suggests that aerial concentrations of 102–103 times the male threshold response level may be sufficient to cause successful communication disruption in the field. The problems of relating the non-oriented responses in an assay of this type to directional responses in traps are briefly discussed.

The distribution of the Sudan HALTICINAE is given, together with brief notes on the food-plants and habits where known, and a key to the species.

Some 39 species, within 19 genera, are known to occur. Many are of minor economic importance, but three can be ranked as major pests. These are the two cotton flea-beetles, Podagrica puncticollis Weise and P. pallida (Jacoby), and Phyllotreta cheiranthi Weise on cruciferous vegetables.

The natural predators of larvae and pupae of the complex of Simulium damnosum Theo., most probably S. soubrense Vajime & Dunbar and S. sanctipauli Vajime & Dunbar, in the River Marahousé in the Ivory Coast were identified by serological methods. Rabbits were injected with cell-free saline extracts of S. damnosum larvae to produce S. damnosum antiserum, which was used in interfacial capillary ring tests. A total of 1648 gut smears was made from various aquatic invertebrates and tested, and Trichoptera larvae were identified as the most important predators.

The discovery of a species of Phlebotomus in Australia is of considerable interest in view of the fact that the genus contains several exotic species known to be the vectors of specific fevers in man (verruga, pappataci fever, etc.).

Estimates of the size of populations of the red locust, Nomadacris septemfasciata (Serv.), in their outbreak areas have been made in Tanganyika from counts of adults caused to fly up by the approach of a slowly moving vehicle. For research purposes it was desirable both to improve and estimate the accuracy of such assessments. For control purposes it was desirable to devise an objective aerial assessment technique which could be used in areas where ground methods were either impracticable or expensive. The errors involved in both ground and air estimates can be divided into those concerned with the ratio of locusts counted in the sample area to those actually present, and those concerned with the distribution of the locusts.

It was found that a Land-Rover moving at five miles an hour, with the wind blowing from a rear quarter, flushed a high and virtually constant proportion of locusts during most of the day and in the most important grasses of the Rukwa outbreak area, throughout the dry season. Variation in locust density and in the state of the grass had little effect, if any, on the value of the equivalent strip (e), i.e., a strip whose width is such that the number of locusts in it is equal to the number flushed by the vehicle in a strip equal in width to its own. The change with time, and thus presumably with locust behaviour, in the value of e, estimated as recommended, was small but significant.

Counts by various observers in one vehicle gave similar results and it seems likely that, even with high numbers, there was no systematic mis-estimation. This is almost certainly true for counts of under a hundred locusts flushed per 0·1 mile. With upwards of one thousand 0·1-mile counts in each assessment, it is believed that the random errors due to mis-counting of the locusts flushed will be negligible.

The locusts are always distributed in an over-dispersed manner, consequently normal techniques for ascertaining the standard error of estimate cannot be used. Three assessments were made by the methods recommended, using a grid of two-mile squares; in one case, where the distribution was very gregarious, the most densely populated sector was more intensively sampled. The standard error of assessments laid out in this way was estimated. The method of analysis overestimates the standard error to some degree. Alternatively, the standard error resulting from the nature of the locust distribution can be computed for assessments where the 0·1-mile counts can be shown to be distributed log-normally.

Provided the population assessment is carried out under the conditions stipulated above, the additional errors will be minor. The effect of such errors will be likely to be so small that the estimated standard error, derived from the lognormal or assessment-grid analysis, may be regarded as a valid estimate of the standard error of the population estimate.

An attempt was made to estimate populations of the red locust in part of an outbreak area from locusts flushed by a ‘ Prospector ’ aircraft. The trials suggested that, given a clear rear view, red locusts which were flushed could be identified as such. Further, the number of locusts flushed could be counted at low densities, and it is thought likely that a reasonably objective technique could be developed for estimation at higher densities.

Flushing appeared to be most effective at an aircraft height of 20 ft. or less and when the direction of flight was with the wind. However, the majority of locusts present failed to take off and the proportion which did rise varied very greatly. The spraying of concentrated ammonia under pressure increased the efficiency of flushing.

A large-scale comparison of air and ground assessments suggested that, under the prevailing conditions, a considerable proportion of the locusts could be flushed only from the dense concentrations. At all densities the proportion of locusts which the aircraft caused to rise was a small fraction of those present. With flushing of such a low level of efficiency, little idea could be obtained of the size of the locust population at a moderate or low density.

Blosyrus aequalis, Har. 1879.

This species, originally described from Angola, has recently been bred from larvae found in tubers of sweet potatoes at Haut-Lepori, Belgian Congo, by Lieut. J. Ghesquière.

In theory, inferior apparent competitors sharing a natural enemy with superior apparent competitors should be excluded in the absence of stabilising factors. Nevertheless, plentiful examples of coexisting apparent competitors exist. In this paper, we show that parasitoid resource competition within hosts affects both parasitoid sex ratio and female body size, with implication for population growth and apparent competition between the two closely related hosts experiencing a strong asymmetry in their interaction. While the superior competitor delivers parasitoids with higher fitness to the shared parasitoid pool, the inferior competitor delivers a higher proportion of female parasitoids. Hence, the inferior host experience an inflow of fit parasitoids from the superior competitor, which should increase the risk of exclusion, but also an outflow of parasitoid females, which should reduce the risk of exclusion and increase stability. We conclude that differential outcomes of parasitoid resource competition in different host species may have profound effects on shared parasitoid populations and should be included in future studies of apparent competition between hosts.

Following the introduction and establishment of Rhabdionvirus oryctes in Mauritius, seven adults of Oryctes rhinoceros (L.) were found with external malformations ranging from slight deviation at the base of the elytra to almost complete atrophy of the wings and elytra. Histological abnormalities of the midgut are described from a sample of 46 beetles of which 36 proved to be infected; infected epithelial cells are discharged into the gut lumen and so into larval and adult habitats.

The flight activity of Chrysopa carnea Steph. was studied during 1970–77 using 21 suction traps sited between 50 and 58°N. in northwestern Europe. Flight continues until late October and early November, well beyond the time (late August) when reproductive diapause is initiated at these latitudes. Flight ends as an all-or-none response to changing daylengths, the most northern populations having a shorter critical photoperiod, about 10 h 20 min, between morning and evening civil twilights, than the most southern ones, the critical photoperiod of which is about 10 h 45 min. By contrast, the critical photoperiod for induction of reproductive diapause is longer in northern populations. At latitudes less than 30° N. there is no winter dormancy but there is sometimes aestivation during the hottest period of the summer. In C. carnea, uniquely, winter dormancy has two distinct components, reproductive diapause and loss of flight activity, each controlled independently by photoperiod.

The coffee berry borer (CBB), Hypothenemus hampei (Ferrari), is a multivoltine species closely associated with coffee crops worldwide, causing severe damage to the bean. In Mexico, as in all tropical regions, CBB survives during the inter-harvest period in residual berries on the ground or in dry berries remaining on the branches, and then disperses in search of the first suitable berries. In this study, we investigated how CBB dispersed from the first infested nodes during the fruiting period of Coffea canephora Pierre, which provides a favourable trophic level for this insect. Forty-five branches equally distributed in 15 coffee trees, with one infested node and four uninfested nodes, were selected. The branches were subjected to three treatments over nine weeks: 1) glue between nodes with full protection, 2) glue between nodes without protection, and 3) no glue and no protection. In addition, 45 CBB-free branches were selected and subjected to the same three treatments. CBB colonization can occur in three ways: 1) from an infested node to an uninfested node on the same branch, 2) from infested berries to uninfested berries within the nodes, 3) from branches to other branches. We also found that CBB dispersal between nodes of the same branches never occurred by walking but by flying. Thus, in this context of coffee berry development and ripening, and unlike the phenological situation of the inter-harvest period, CBB continuously travels very short distances, thus limiting its control.