Light-trap catches of Dysdercus bimaculatus Stål and weekly phenological records of its host-plants over a period of three years on Barro Colorado Island, Panama, are discussed in relation to a year-long study of population growth at selected plants. Population build-up of D. bimaculatus occurred on a sequence of seed crops from wild host-plants in the dry season. Each year, the largest number of bugs caught in the light-trap occurred after a drop in vapour pressure deficit marked the end of the dry season. Thus, the population appears ‘poised’ to attack cotton crops maturing in the late wet season. A stepwise linear regression indicated that each year, the variance in size of Pseudobombax septinatum crops (maturing at the end of the dry season) explained the largest proportion of variance in the light-trap capture of D. bimaculatus. However, estimates from the field study indicated that Ceiba pentandra crops were more important than P. septinatum in building up numbers of adult cotton stainers. The discrepancy between the field study and the longterm phonological monitoring survey would be resolved if D. bimaculatus adults experience a dispersal flight at the end of the dry season. This flight would enable the insect to locate better-quality seed crops in drier habitats that mature in the late wet season, such as Sterculia apetala or cotton. Light-trap captures at the end of the dry season in areas such as Barro Colorado Island where Ceiba and Pseudobombax occur, could be an index to the intensity of attack on cotton crops in nearby drier areas.

There are in the Sudan three species of migratory locusts : Anacridium moestum melanorhodon, Walk., or the tree locust, Locusta migratoria, L., and Schistocerca gregaria, Forsk., sometimes termed the desert locust. Of these the last-named is the plague locust of the country—the other two species being relatively unimportant—and is the species referred to as the “ locust ” throughout this paper.

From 1899 till 1917 swarms of locusts occurred annually, but then followed a period of ten years during which the Sudan suffered no damage from this pest. In 1927 and again in the succeeding year the locust reappeared as a plague, and there is little doubt but that it is to be expected year by year over an extended period and until the cycle either naturally terminates or is artificially brought to an end. The swarms of fliers appear from May onwards and oviposit in July and August when and where in the arid regions sufficient rain has fallen, the resulting generation of adults emigrating in October. A certain amount of breeding takes place during the winter on the Red Sea littoral, where winter rains occur, but this district is relatively small and easily dealt with ; the main problem is how to prevent breeding during the summer rainy season throughout the vast areas of the central and northern Sudan.

The following mosquitos should be added to the list given in my earlier paper on this subject (Bull. Ent. Res. 28, 1937, pp. 405—407).

1. Anopheles elutus, Edwards.

The larvae are found in the same habitats as those of A. maculipennis, but seem to show a greater preference for waters near the sea-shore. A. elutus appears to be considerably rarer in Corfu than A. maculipennis, but sufficient data are not yet to hand to settle this question.

2. Anopheles plumbeus, Stephens.

Not common. I have obtained the larvae from the rot-holes of oak, elm and white poplar, but never so far from those of olive-trees. They favour deep holes containing plenty of rotting material.

3. Aëdes (Ochlerotatus) caspius, Pallas.

The larvae are sometimes present in fresh, but more frequently in slightly brackish waters. They are often gregarious with the larvae of O. detritus, Hal., but are much less abundant than the latter.

4. Aëdes (Ochlerotatus) pulchritarsis, Rondani.

The larvae live in rot-holes of oak, elm and white poplar, and are sometimes met with in considerable numbers in the same hole. They prefer holes in which the collected water has become thick and very dark amber in colour owing to the presence of decaying wood debris.

5. Orthopodomyia pulchripalpis, Rondani.

The larvae are found in the same habitats as those of O. pulchritarsis and are often gregarious with the latter. They are less plentiful, on the whole, than O. pulchritarsis and prefer somewhat clearer water.

Note.—In my paper referred to above I mentioned that Finlaya echinus, Edw., is commoner in Corfu than F. geniculatus, Oliv. This statement is due to an error of determination arising from the fact that in many of the Corfu larvae of F. geniculatus the bristles of the abdominal tufts are somewhat more developed than those described in some text-books.

In the course of a search for parasites of Cercopidae in Central America, made on behalf of the Government of Trinidad in 1916 and 1917, I came across a froghopper of the genus Clastoptera destroying the flowers of cacao in various localities in Panama and just over the border in Costa Rica.

A breeding-place of Glossina pallidipes Aust., in evergreen shrubs of Craibia sp. on the Kiangine river, Makueni, Kenya, was studied by means of hand-searching for puparia in conjunction with records of rainfall and temperature. A fly-patrol was also operated. The country away from the river was thorn-scrub, with Acacia and Commiphora trees predominating.

Three sites, each of 200 sq. yards, divided into 50 squares, were marked out, and two of them were searched monthly and the third quarterly.

Site “ A ” was searched nearly every month between April 1949 and June 1952, and full puparia were nearly always found. Numbers varied very widely; and it was noted that few could be found in rainy seasons during the months of November to January and April to May, though 1950 was an abnormal year. A consistently large increase in numbers was observed in February, the hottest and driest month, and a rather less marked increase towards the end of the long dry season in September and October. Large numbers of full puparia also tended to coincide with times of low average minimum temperature.

The numbers of flies caught on the fly-patrol did not appear to bear any close relation to the numbers of full puparia discovered.

Testing for efficiency of searching by means of marked puparia showed that about 40 per cent. of puparia were recovered, so that results must be taken as relative.

Pyrgomorphella arachidis, sp. n.

♂ (Type). Of medium size, slender, finely rugulose.

Antenna of 17 segments, shorter than head and pronotum together, thick, slightly flattened and scarcely broadened at the base. Fastigium of vertex long, parabolic, ratio of its length to the width between eyes, 1·8. On the lateral sides of head behind the eyes there is a series of callosities forming a longitudinal stripe, which continues on to the lateral lobe of pronotum.

In 1925 a brief generalised account was given of the biology of Sacadodes pyralis, Dyar, a Noctuiid moth that appeared likely to prove to be a serious pest of cotton, should the cultivation of this crop be taken up on a large scale in Trinidad. Previously little attention appears to have been paid to the potential danger, which the writer considers to be very real.

Sacadodes is not only very closely allied to Diparopsis castanea, Hampson, the Sudan bollworm, but it is also remarkably similar to that insect both in the general facies of all stages (Plates xxi and xxii) and in its bionomics.

So far no species of this family of Diptera have been described or recorded from the Samoan Islands. The acquisition of a species of Tabanus by Dr. P. A. Buxton and Mr. G. H. E. Hopkins is therefore of great interest.

The Tabanidae of the Pacific Islands undoubtedly form an eastward extension of the family from Papua through Melanesia to Fiji ; various species are known from the Solomons, New Hebrides, New Caledonia, the Loyalties and Fiji, but the family is unrecorded from Tonga or islands to the eastward of Samoa. The Tabanidae thus represent a Papuo-Melanesian element in the Polynesian fauna. It might be mentioned here that two species of Tabanus, T. sidneyensis and T. nigriventris, were described by Macquart from “ Sidney Island,” which has been supposed to be Sidney Island in the Phoenix group. This locality is certainly erroneous ; most of the Diptera described as coming from there are known now to be common Australian forms and these two species are in all probability also Australian. The only other species recorded from Polynesia proper is T. insularis, Walker, described from the Sandwich Islands ; this record is also certainly wrong, since the group is not known to occur in these islands, of which the fauna has been extensively collected.

The puparia of some Cyclorrhaphous Diptera resemble and are found among those of tsetse flies (Glossina spp.). Those of Plesiocyptera sp., Argyrophylax aureiventris (Villen.) (Tachinidae) and? Physocephala (Conopidae), are described and illustrated, as are the larval cephalopharyngeal skeletons recovered from the puparia.

A recent study on ladybird, Menochilus sexmaculatus (Fabricius) demonstrates that males perform post-copulatory mate guarding in the form of prolonged mating durations. We investigated whether food resource fluctuation affects pre- and post-copulatory behaviour of M. sexmaculatus. It has not been studied before in ladybirds. For this, adults were subjected to prey resource fluctuations sequentially at three levels: post-emergence (Poe; 10 days), pre-mating (Prm; 24 h) and post-mating (Pom; 5 days; only female). The food resource conditions at each level could be any one of scarce, optimal or abundant. Pre-copulatory and post-copulatory behaviour, and reproductive output were assessed. Post-emergence and pre-mating nutrient conditions significantly influenced the pre-copulatory behaviour. Males reared on scarce post-emergence conditions were found to require significantly higher number of mating attempts to establish mating unlike males in the other two food conditions. Under scarce post-emergence and pre-mating conditions, time to commencement of mating and latent period were high but opposite result was obtained for mate-guarding duration. Fecundity and per cent egg viability were more influenced by post-mating conditions, with scarce conditions stopping oviposition regardless of pre-mating and post-emergence conditions. Present results indicate that pre- and post-copulatory behaviour of ladybird is plastic in nature in response to food resource fluctuations.

Novel ecosystems formed by invasive plants provide a good opportunity to get insight into early dynamics and pattern formation of these ecosystems. The invasive black locust as host plant, Bruchophagus robiniae as host-specific seed predator and its parasitoids were the components of the studied tritrophic system. To investigate disturbance-driven dynamics of this system we created seed-vacated host plant patches in a field experiment. We removed all pods from selected patches of black locust resulting in an induced local extinction of seed predators and their parasitoids. We hypothesized that disturbance enhances top-down control by parasitoids; this enhanced top-down control decreases seed predation, facilitating the host plant's spread. We found that disturbance modified only parasitism after controlling with year effect: in vacated patches median parasitism was higher than in control patches. Seed predation exceeded its initial level in vacated patches in the third year after the disturbance, but in the fourth year it dropped again presumably due to the strong top-down control. Our findings also suggested that the seed predator was also affected by the bottom-up control of its host plant's density. We found that in the studied new ecosystem the top-down control was strengthened by the disturbance. Since the host plant of the tritrophic system is an invasive species, partial habitat disturbance of such species may increase the severity of parasitoid top-down control, which may reduce seed predation by the herbivores.

Females of the white grub beetle, Dasylepida ishigakiensis, release both (R)- and (S)-2-butanol as sex pheromones, but the males are only attracted to (R)-2-butanol. In laboratory-reared females, the proportion of the (R)-isomer decreased significantly as their calling opportunities increased and as they aged. We examined whether such qualitative changes also occur in field populations. We collected virgin females from the field and then trapped and analysed the volatiles emitted during their first and second callings. The ratio of (R)- to (S)-2-butanol (R/S) was 78:22 at the first calling, but shifted to 39:61 at the second calling. While investigating the composition of the female pheromones, the question arose as to whether the male preferences change in response to the shift in female pheromone composition. To answer this question, we observed the behaviour of young and old males in response to various R/S ratios as lures in the laboratory and in the field. In the flight tunnel assay of laboratory-reared individuals, young males touched female models with a 9:1 R/S ratio lure less than those with pure (R)-2-butanol; however, older males touched the two groups with equivalent frequency. In the field trap test, older males were much more attracted to (R)-2-butanol-scented lures. When we tested using lures with the same amount of (R)-2-butanol but added different amounts of the (S)-isomer, we found that increased levels of (S)-2-butanol resulted in lower attractiveness to males. (S)-2-butanol was confirmed to have an inhibitive activity in the attractiveness of (R)-2-butanol.

Chickpeas (Cicer arietinum L.) belong to the Fabaceae family and are one of the most grown crops in the world and an important source of protein for humans. Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) is a polyphagous pest that causes significant crop damage. The objective of this study was to examine antibiosis to S. frugiperda in chickpea genotypes. The following genotypes were studied: Jamu 96 and Blanco Sinaloa 92 (Mexico); Nacional 29 (Cuba); BG 1392 (Spain), and BRS Kalifa, BRS Cristalino, BRS Toro, Nacional 27, 004UP, 003UP, BRS Cícero, and BRS Aleppo (Brazil). The chickpea genotypes influenced the biological parameters of S. frugiperda, of which larval period, larval weight, and pupal period were most affected. Nacional 29 caused high mortality in the larval and pupal stages of S. frugiperda. The larvae on BRS Aleppo had the longest larval stage, lowest weight, and longest pupal stage. The genotypes Nacional 29, Nacional 27, and BRS Cícero showed antibiosis resistance to S. frugiperda. These genotypes could be used as a source of resistance to S. frugiperda in conjunction with other methods of pest control in integrated pest management programs for chickpea crops. These resistant genotypes could also be used as donor sources in breeding programs for insect resistance.

Mosquito communities across the globe frequently comprise a mix of native and cosmopolitan species. New Zealand's mosquito communities are no exception. Here we describe the abundance, distribution and phenological patterns for a community of six mosquito taxa resident across the Kaipara Harbour region of northern New Zealand. Adult mosquitoes were sampled using baited light traps, serviced biweekly for 3½ years. Seasonal fluctuations in abundance of adults were examined for correlations with temperature and rainfall over the preceding weeks. Four endemic species comprised over 98% of the total catch, with Coquillettidia iracunda being the most abundant. Two introduced species, Aedes notoscriptus and Culex quinquefasciatus were widely distributed, but each comprised <1% of the total catch. Culiseta tonnoiri was the only species that appeared geographically restricted, occurring at one-third of the sites. Distinct temporal peaks in adult abundance were evident: Aedes antipodeus was most abundant in spring, Ae. notoscriptus and Cq. iracunda were most abundant in summer and Cx. quinquefasciatus was most abundant in autumn. Culiseta tonnoiri and Culex pervigilans were of variable abundance throughout the year. For all species examined, temporal variations in abundance were more strongly associated with temperature in the preceding weeks than with preceding rainfall. A better knowledge of the factors driving patterns of spatial and temporal abundance will allow an improved understanding of how non-native species may integrate themselves into resident mosquito communities.

The relative contributions of host plant, herbivore species and clone to variation in the interaction between cereal aphids and wheat were investigated using five clones each of three species, Rhopalosiphum padi (Linnaeus), Sitobion avenae (Fabricius) and Schizaphis graminum (Rondani), on seedlings of two cultivars of Triticum aestivum L. and one cultivar of Triticum durum Desf. More individuals and biomass of R. padi than of the other two species were produced on seedlings. The three wheat cultivars lost similar amounts of biomass as a result of infestation by aphids, with the amount lost depending on aphid species: S. avenae caused the lowest loss in biomass. Variation in aphid biomass production was due mostly to differences among aphid species (70%), less to the interaction between wheat type and aphid species (7%), and least to aphid clone (1%). The specific impact of the aphids on the plants ranged from 1.7 to 3.7 mg of plant biomass lost per mg of aphid biomass gained, being lowest for R. padi and highest for S. graminum. Variation in plant biomass lost to herbivory was due mostly to unknown sources of error (95%), probably phenotypic differences among individual seedlings, with 3% due to aphid species and none attributable to aphid clone. For these aphid–plant interactions, differences among aphid clones within species contributed little to variation in aphid and plant productivity; therefore, a small sample of clones was adequate for quantifying the interactions. Furthermore, one clone of each species maintained in the laboratory for about 200 parthenogenetic generations was indistinguishable from clones collected recently from the field.

The larvae and pupae of Tryporyza innotata (Wlk.), T. incertulas (Wlk.), Chilo suppressalis (Wlk.), C. polychrysa (Meyr.) (Pyralidae) are described and notes are given on Sesamia ingerens (Wlk.) (Noctuidae) with particular reference to setal characters of the larvae. No obvious difference in chaetotaxy was found between T. incertulas and T. innotata, but the two species of Chilo could be distinguished on this basis. The pupae of the species of Tryporyza could be separated by differences in the shape of the labrum and those of the species of Chilo by differences in that of the thoracic tubercles.