The determination of mealybugs closely related to Pseudococcus comstocki (Kuw.) has presented considerable difficulty in the past. Green (1921, p. 189) and Hough (1925, p. 52 and 1925a, p. 13) have given details of the distinguishing features for P. comstocki (Kuw.) and P. maritimus (Ehrh.) but the grounds given for the separation of the former from other closely related species are not fully satisfactory. The representatives of this group of mealybugs are becoming more and more widely spread throughout the world and of greater economic importance yearly. A correct designation of these insects is, therefore, of particular importance not only from the point of view of quarantine legislation but also of control measures. Research work on the morphological characteristics of species closely related to Pseudococcus comstocki (Kuw.) has been carried out on very large quantities of material from different parts of the world.

To understand the effect of plant availability/structure on the population size and dynamics of insects, a specialist herbivore in the presence of two of its parasitoids was studied in four replicated time-series experiments with high and low plant availabilities; under the latter condition, the herbivore suffered from some periods of resource limitation (starvation) and little plant-related structural refuges. Population dynamics of the parasitoid Cotesia vestalis was governed mainly by the delayed density-dependent process under both plant setups. The parasitoid, Diadegma semiclausum, under different plant availabilities and different coexistence situations (either +competitor or –competitor) showed dynamics patterns that were governed mainly by the delayed density process (significant lags at weeks 2–4). Both the competing parasitoids did not experience beneficial or costly interferences from each other in terms of their own population size when the plant resource was limited. Variation in the Plutella xylostella population under limited plant availability is higher than that under the other plant setup. For both parasitoids, under limited plant setup, the extinction risk was lower when parasitoids were engaged in competition, while under the unlimited plant setup, the mentioned risk was higher when parasitoids competed. In this situation, parasitoids suffered from two forces, competition and higher escaped hosts.

Tamarixia leucaenae sp. n. is described from Trinidad as a parasitoid of Heteropsylla cubana Crawford. The psyllid is a serious pest of Leucaena leucocephala, which is used as a shade tree in plantations of various crops in the tropics.

In the spring of 1932 the President of the International Locust Office at Damascus invited me to visit the main breeding areas of the Moroccan Locust (Dociostaurus maroccanus, Thunbg.) within the territories of the states adhering to that Office, i.e. Turkey, Syria and Iraq, in order to survey the local locust problem and to advise on the best general policy of locust control. The visit represented partly a continuation of the previous season's work in Western Anatolia (Uvarov, 1932) and concerned the great locust area which comprises the south-eastern vilayets of the Turkish Republic, the northern provinces of Syria and northern Iraq.

The voyage was planned to take place at the period when oviposition by locusts usually occurs, and about three weeks in the second half of May and early June were spent in actually touring the areas subject to regular locust invasions in Iraq and Syria. Unfortunately, no arrangements were made for including Southern Turkey in the tour and, therefore, an important section of the area remained unstudied.

While the choice of the period for the ecological investigations proved to be correct, the year was scarcely favourable for reaching very definite conclusions. Locust swarms were numerous and rather widely spread during at least two or three previous years, but the meteorological conditions of the early spring of 1932 were quite exceptional, owing to the practical absence of rains, which caused great mortality amongst young hoppers.

Spodoptera litura is an important pest that causes significant economic damage to numerous crops worldwide. Sex pheromones (SPs) mediate sexual communication in S. litura and show a characteristic degree of rhythmic activity, occurring mainly during the scotophase; however, the specific regulatory mechanisms remain unclear. Here, we employed a genome-wide analysis to identify eight candidate circadian clock genes in S. litura. Sequence characteristics and expression patterns were analyzed. Our results demonstrated that some circadian clock genes might regulate the biosynthesis and perception of SPs by regulating the rhythmic expression of SP biosynthesis-related genes and SP perception-related genes. Interestingly, all potential genes exhibited peak expression in the scotophase, consistent with the SP could mediate courtship and mating behavior in S. litura. Our findings are helpful in elucidating the molecular mechanism by which circadian clock genes regulate sexual communication in S. litura.

The systemic insecticide Hanane (mainly bisdimethylamino fluorophosphine oxide) is readily absorbed by the trunk of a coffee tree and translocated to the foliage when the bark is lightly scraped and the chemical applied in solution on a pad of absorbent material covered with a waterproof skin to prevent evaporation.

Smaller dosages of Hanane are required to give equivalent control of Planococcus kenyae (Le Pelley), or to cause a similar degree of phytotoxic damage, by this method than by soil treatment.

Abrasion or removal of the bark before application enables a greater absorption of the chemical but leads to serious phytotoxic damage by a comparatively low dosage.

The purpose of this paper is to direct attention to the possibilites of sodium fluoride as an insecticide. Recent investigations of this salt as a stomach poison, which I have undertaken with cutworms and locusts, as well as its few but successful previously known uses as an insecticide against fowl-lice, Mallophaga on mammals, cockroaches, and earwings, indicates that sodium fluoride may, in a number of cases, replace the use of arsenical poisons. During the past decade the use of arsencial insecticides has increased rapidly. We are at present threatened with higher prices and possibly with a shortage of arsenic, a situation accentuated by the present cotton-boll weevil programme of the United States of America, which involves the use of tremendous quantities of arsenicals. Any cheap stomach poison effective against insects and promising as a substitute for arsenicals should therefore be of considerable interest to the entomologist and to the farmer, especially if it carries the additional advantage of being considerably less poisonous to man, stock and birds. Sodium fluoride meets these requirements.

The distribution, habitat and cultivated and wild host-plants of the four species of Oxycarenus found in Ghana are given. O. hyalinipennis (Costa), primarily a savanna species, attacks the seeds of okra, kenaf and cotton; the other species are unlikely to attain pest status. A key to the species is given.

One or two errors in “ Mosquitoes of the Ethiopian Region ” have recently come to light, and several new Culicine larvae have been discovered since the first volume was published. I take this opportunity to correct the errors and to indicate the positions which the newly-described larvae should occupy in the keys. I have not seen most of these larvae and have inserted them in the keys solely from the descriptions.

A number of the mosquitos of which I described the larvae in Vol. I of the monograph were incorrectly determined, but Edwards has already pointed out these misdeterminations (in Vol. III) and I have not thought it necessary to mention them here.

At the request of Mrs. G. R. Cunningham van Someren (formerly Miss E. C. C. Macdonald), I have added her description and figure of the larva of Aëdes adersi and her description of that of Culex adersianus as an appendix (see p. 178).

Clear pale lemon yellow. The antenna with the 4th to 9th joints very pale grey. Third joint very small, a little longer than broad, about half the length of the second joint. Fourth joint rather slender, the length of the 2nd and 3rd taken together. The fifth about one-quarter shorter, about the same width. The 6th, 7th and 8th subequal, about the same length as the 5th but rather broader. Wings hyaline, with a very slight shadow below the vein, very nearly nine times as long as the greatest width (·525 × ·06 mm., approximately). Marginal cilia moderately strong, the longest ·132 mm. There is a line of hairs running along the middle of the wing from the apex of the vein to near the apex of the wing ; between this and the front margin there is another line of about twelve hairs, rather irregular, and there are a few hairs irregularly placed in the apical area. Between the central line and the hind margin there is an irregular line of about eight hairs, but they are not the same on both wings. Hind wings free from surface hairs, except three or four at the extreme apex. The posterior cilia moderately stout, except the first three or four, the longest about ·1 mm.

It has been pointed out by Graham* that measures designed to bring about the destruction of mosquito larvae may be divided into (a) measures intended to destroy the larvae, and (b) measures intended to destroy their food supply. He points out that very little attention has been paid to the second method, which entails an exact knowledge of the freshwater algae. Graham found that the suspended matter in water in which the larvae of Pyretophorus costalis were breeding could be precipitated by the addition of 3 per cent, of common salt, and that then the larvae became cannibalistic and destroyed one another. He considered that this phenomenon was due to the larvae being deprived of their natural food, the algae, which had been destroyed by the addition of salt. “In lesser concentration,” he concluded, “salt appears to inhibit the growth of very young larvae, probably by diminishing the supply of food, but the development of fully-grown larvae appears to be hastened in a hypertonic medium, and they pass into and through the pupal stage with unusual rapidity.”

Amongst some insects bred this year from Lecanium viride on coffee in Mauritius, and forwarded to the Imperial Bureau of Entomology for identification by M. d'Emmerez de Charmoy, were two species of Chalcids belonging to the genera Diversinervus, Silv. (1915) and Tetrastichus, Hal. (1843) respectively. The former, which appears to differ considerably from the genotype, is here described as a new species ; the latter so closely agrees with Tetrastichus sicarius, Silv., that I have not thought it advisable to propose a new name. My best thanks are due to Professor Silvestri for his kindness in examining preparations of both species.

Diapause development in Contarinia sorghicola (Coquillett) was found to be favoured by temperatures in the range 23–30°C. Higher temperatures (30–35°C) were suboptimal, while diapause development proceeded much more slowly at lower temperatures (5–20°C). The rate of diapause development was linear, and no minimum threshold development temperature could be established from the range of temperatures studied (lowest 5°C). The period from diapause initiation to emergence (diapause development requirement plus a 2·5-week post-diapause development requirement) was predicted to be 6 months at 27°C and 7·5 months at 23°C. It is suggested that C. sorghicola probably evolved a diapause stage in response to the absence of its host-plant during the long dry season of the African savanna region. The possibility of strains with differential diapause reactions is raised. Sex ratios favoured females slightly.

Descriptions are given of the nymphs of five species of ticks from the eastern Cape Province of South Africa, namely Amblyomma marmoreum Koch, A. nuttalli Dönitz, Hyalomma marginatum rufipes Koch, Rhipicephalus evertsi Neumann and Ixodes pilosus Koch. Distinguishing characters are illustrated in 32 scanning electron micrographs.

The flee-weevil Orchestes steppensis Korotyaev (Coleoptera: Curculionidae) is a steppe eastern Palaearctic species, notable as a serious pest of elms (Ulmus spp., Ulmaceae), by feeding on the leaves (adults) or mining them heavily (larvae), especially of Ulmus pumila L. in Xinjiang, China. We have corrected the previous misidentifications of this weevil in China as O. alni (L.) or O. mutabilis Boheman and demonstrated that it is likely to be an invasive species in Xinjiang. Prior to this study, natural enemies of O. steppensis were unknown in Xinjiang. Resulting from field investigation and rearing in the laboratory during 2013–2016, seven parasitoid species were found to be primary and solitary, attacking larval and pupal stages of the host weevil. Pteromalus sp. 2 is the dominant species and also is the most competitive among the seven parasitoids, which could considered to be a perspective biological control agent of O. steppensis. Yet, the current control of this pest by the local natural enemies in Xinjiang is still currently inefficient, even though in 2016 parasitism was about 36% on U. pumila in Urumqi, so the potential for a classical biological control program against it needs to be further investigated, including an assessment of its parasitoids and other natural enemies in the native range of O. steppensis. The presented information on the natural enemies of this weevil can be also important for a potential classical biological control program against it in North America (Canada and USA), where it is a highly damaging and rapidly spreading invasive species.

This mite was described by Froggatt as attacking oats in New South Wales in 1921 (Agric. Gaz. N.S.W. 3rd Jan. 1921) under the name of Notophallus bicolor, sp. n., but with a very inadequate description. In my paper of 1933 “ On some Acarina from Australia and South Africa ” (Trans. Roy. Soc. South Aust. 57, pp. 108–112) I recorded it from the Cape Town area of South Africa, as well as from certain States of the Australian Commonwealth, giving a redescription and detailed figures. The generic name was changed to Penthaleus, as it had been shown that Notophallus of Canestrini 1886 was synonymous with Koch's Penthaleus of 1838. At that time, although so far as I was aware no recent redescription of any of the European species of Penthaleus had been published, I gave P. bicolor (Frog.) as doubtfully synonymous with P. major (Dugès 1834), a species considered by European workers as the same as P. haematopus, Koch 1835, and P. insulanus, Thorell, 1872.

Aedes (Ochlerotatus) fryeri (Theo.) was found developing in saline pools on the coastal margins of coral islands near Dar es Salaam, Tanzania. Females were autogenous in the first ovarian cycle and anautogenous in the second ovarian cycle. The existence of autogeny was confirmed by examination of females reared from field-collected pupae and of the age structure of the population of females landing and biting. All females receiving carbohydrate and most females receiving only water as adults exhibited autogeny; only parous females were caught attempting to take blood. Water-fed females (and to a lesser extent, carbohydrate-fed females) showed a high incidence of follicular regression in the first gonotrophic cycle. The possible adaptive significance of autogeny in A. fryeri is briefly discussed.

Short summaries have previously been given (1938, 1940) of the results obtained during investigations on the wood-destroying insects in public buildings in Götaland and Svealand, the southern and middle parts of Sweden. The survey has since been continued in Norrland, the northern part of the country, and a short summary of the results obtained may now be given, together with a general survey of the conditions prevailing in the whole country.

The subterranean termite Reticulitermes grassei Clément causes lesions in the trunk of Quercus suber L. by constructing feeding galleries, but no information is available regarding other Quercus species from the Mediterranean region. This work aimed to study the suitability of the other main oak species of Mediterranean forests as a food resource for R. grassei. Two experiments, choice and non-choice feeding, were conducted lasting for 15, 30, and 45 days each. In the non-choice experiment, termites were offered one of the following food types: Quercus suber, Quercus ilex L., Quercus faginea Lam, cork or Pinus pinea L., which was considered the control. The choice feeding experiment used all the same food types listed above, supplied simultaneously in the same container. Food selection was examined by analysing the relationships over time between surviving termites and food consumption. The results indicated that R. grassei could be considered a generalist species, as it consumed the cork and wood of all oak species, as well as displaying a clear preference for soft wood (pine). Correlation analysis indicated that consumption was not dependent on wood density. Survival of R. grassei was influenced by the time of exposure to different oak species, but a high survival rate was maintained over time in the pine treatment (upper 70% in the three experiments). Given these results, it can be concluded that all the oak species are a suitable food source for R. grassei.

As a general rule, on the Benue River and its tributaries, at least between Abinsi and Lau, the tsetses found are Glossina tachinoides and G. palpalis, the latter occurring far less frequently.