Growth of larvae of the whitefringed weevil, Graphognathus leucoloma (Boheman), was studied in the laboratory and on various crops in pots in a shadehouse at Kairi, on the Atherton Tableland in north Queensland. In the laboratory at 25.5 ± 1°C there were 11 instars for which head capsule widths and weights were recorded. The first instar weighed 0.14 mg. This was a non-feeding stage capable of prolonged survival, and after 10 weeks in soil without food 60% survived. When provided with carrot (Daucus carota) larvae grew to 2 or 3 mg after 6 to 7 weeks, then increased rapidly in weight reaching 140 mg after 120 days. At 25.5°C the average time from first instar to adult was 311 days, due in part to a long prepupal period. Larval growth was measured on the roots of peanut (Arachis hypogaea) plants in pots in summer and winter. Under summer conditions (mean soil temperature 23.3°C) larvae reached 140 mg in about 120 days, similar to that in the laboratory on carrot. These fully grown larvae remained in the pots over the mild winter without pupating. Larvae developing in autumn/winter grew more slowly, but the fully grown larvae were then exposed to high spring (early summer) temperatures and soon pupated, the average time from first instar to adult being 273 days. The indications are that temperatures above 25°C quickly precondition mature larvae from Tolga for pupation, thus explaining the broad timing of adult emergence in the field in north Queensland. On different plants common near Tolga, larvae grew most quickly on peanuts and on the pasture legumes dolichos (Lablab purpureus) and stylosanthes (Stylosanthes guianensis). Survival on maize equalled that on peanuts (46.5% in sterilized soil) but growth was less. Larval survival and growth on the grass crowsfoot (Eleusine indica), and (surprisingly) on the pasture legume glycine (Neonotonia wightii) was very poor.

Phenotypic plasticity is thought to evolve in response to environmental unpredictability and can shield genotypes from selection. However, selection can also act on plastic traits. Egg-laying behaviour, including clutch size regulation, is a plastic behavioural trait among tephritid fruit flies. We compared plasticity in clutch size regulation among females of Anastrepha ludens populations stemming from environments that differed in the degree of predictability in egg-laying opportunities. Clutch size regulation in response to hosts of different sizes was compared among flies from (a) a wild, highly isolated population, (b) a wild population that switches seasonally from a small wild host fruit that varies greatly in abundance to an abundant large-sized commercial host, and (c) a laboratory population. Flies from all three populations adjusted clutch number and size according to host size. However, flies from the heterogeneous wild environment were more plastic in adjusting clutch size than flies from agricultural settings that also laid fewer eggs; yet both populations were more plastic in adjusting clutch size in line with host size when compared with laboratory females. When wild and orchard females encountered the largest host, clutch size was extremely variable and egg regulation did not follow the same trend. Heterogeneity in host availability in space and time appears to be as important as seasonal variation in host size in maintaining plastic clutch size regulation behaviour. In stable environments, there was a clear reduction in the plasticity of these traits.

This is a third of a series of papers dealing with zoophagous gall midges of the world. The first, “ Gall Midges as Enemies of Aphids,” was published in 1929 (Bull. Ent. Res., xx, 1929, pp. 433–442) and the second, “ Gall Midges as Enemies of the Tingidae, Psyllidae, Aleyrodidae, and Coccidae,” appeared more recently (op. cit., xxi, 1930, pp. 319–329).

In this paper the species of gall midges whose larvae have been reported as preying on mites are dealt with, the first reference mentioned being in each case that of the original description or record. Practically all the literature available consists of specific descriptions and little is stated about the bionomics of the species with a few exceptions. It is a matter for regret that such scant attention has been paid to this aspect of biological control, especially in view of certain statements claiming that the larvae of various gall midges are of considerable importance in the natural control of red spider. It is with a view to stimulating further research in this direction that the present paper has been compiled.

It has been thought advisable to divide the paper somewhat arbitrarily into separate sections, dealing firstly with those species of gall midges preying on free-living mites and secondly with those species preying on gall-inhabiting mites. A further section deals with those Cecidomyids which may feed on mites. As an additional convenience, a list of plants on which the mites live is appended. The Cecidomyids which may be predacious on mites (see section 5) are not, however, included in this list.

Population densities of mealybugs and other honeydew-producing Homoptera were assessed in six cocoa (Theobroma cacao Linnaeus) trials by inspecting trees from ground to eye level, and also by dissecting samples of terminal buds. A total of 68 cocoa progenies was examined, mainly inter-crosses of six clones. Progenies differed in their levels of infestation with total mealybugs, Planococcoides njalensis (Laing), Planococcus citri (Risso), Phenacoccus hargreavesi (Laing), (Pseudococcidae), Toxoptera aurantii (Boyer de Fonscolombe) (Aphididae), and Mesohomotoma tessmanni (Aulmann) (Psyllidae). Crosses with Amelonado or T63/971 were generally more densely infested with mealybugs than those for example of NA34 and T63/967. Trees of T17/524 parentage were sparsely infested with mealybugs. Rankings of progenies by infestation with mealybugs from the two different sampling procedures were positively correlated, but the relative abundances of individual mealybug species on the trunk and in the canopy differed. Several species of mealybug found in buds were either rare or never found by inspecting trees up to eye level. Correlations between rankings of progenies by order of abundance of Planococcoides njalensis and Planococcus citri were positive and statistically significant, as were those between mealybugs and infestation of buds by T. aurantii or M. tessmanni. The above rankings were negatively correlated with those by aphid and psyllid abundance assessed from inspecting trees up to eye level. The two sampling procedures were complementary but, for economy, samples of buds gave the clearest indication of a progeny's suitability for mealybugs.

The night resting sites of Glossina tachinoides Westw. were observed in riverine forest at Bara, Bauchi State, northern Nigeria. The flies were marked with an ultraviolet-reflecting paint and released at dusk. They were detected with the aid of an ultraviolet lamp. Most of the flies (84·6%) rested on leaves (68·3% on the upper sides) and on small twigs and creepers (11·5%). The resting heights ranged from ground level up to 6·8 m. The average resting height was highest (2·6 m) in the mid-rains at 20.00–24.00 h; however, at 24.00–04.00 h at the same season the mean height was only 1·6 m. Resting height was lowest (1·3 m) in the early rains. Females were found to rest slightly higher than males and, in moonlit periods, both sexes had a tendency to perch higher. The night resting behaviour of G. tachinoides is compared with that of G. palpalis palpalis (R.-D.), which was investigated in an earlier study at the same location. There is much similarity in the behaviour of the two species, but G. tachinoides selects lower resting sites, and a slightly higher proportion of this species is found to rest on leaves as opposed to small twigs

Moths migrating at Muguga, Kenya, were sampled at 24·5 m and 0·6 m above the ground by light-trap. The larger the species, the greater proportion of the sample it represented at the higher level. This effect was independent of family and morphological type. This result is important in considering the evolution of size with respect to orientation and migratory ambit and the role of downwind migration in population dynamics.

Field collections in Bahia State, Brazil, of open cocoa flowers from an untreated plantation and one treated with insecticide and fungicide showed that Homoptera, including the cicadellid Xesrocephalus ancorifer Linnavuori, the aphidid Toxoptera aurantii (Boy.), and species of Pseudococcidae and Margarodidae (Coccoidea), constituted 96% of the total number of insects collected. In the untreated area, Wasmannia rochai Ford formed 22% of the ants collected and Brachymyrmex pictus Mayr, Crernatogaster ? parabiotica Forel,Iridomyrmex sp., Pheidole sp. and Solenopsis sp., a further 48%, whereas in the treated area, 47% were C. parabiotica, 14% W. rochai and 9% B. heeri Forel. There was evidence of a mosaic distribution pattern for the ant species. No cocoa pollen was found on any of the insects collected. Total pollination ranged between 7·4 and 8·1 % and effective pollination between 3·7 and 2·8 % in the treated and untreated areas, respectively. Approximately 76% of the pollen masses were stylar, with 38% of the ball type and 54% of the smear type, whereas the 16% stigmatic pollen masses consisted of 63% ball and 29% smear types; 44% of the stigmatic pollinations were effective, compared with only 33 % of the stylar ones. Some quadrats were more attractive to pollinators than others, and there was a significant positive correlation between percentage effective pollination and insolation, probably due to the favourable effect of sunshine on Forcipomyia activity.

Using laboratory tests described, the effectiveness of a number of insecticides on both larval and adult, fully engorged examples of the Blue Tick, Boophilus decoloratus (Koch), was determined. The results of tests using adult ticks were expressed as histograms of the percentage control exerted by varying concentrations of insecticides. The test using larvae was more sensitive and enabled results to be expressed as dose-response curves from which the LC50 could be accurately calculated. By comparing ticks from different localities in South Africa, resistance to a number of insecticides was demonstrated. Adult ticks from the farms Allandale and Ferndale in the East London district were three to four times more tolerant of sodium arsenite than were the sensitive ticks from Frankenwald farm near Johannesburg. Both larval and adult ticks from Ferndale and Allandale, when compared with Frankenwald ticks, were highly resistant to γ BHC, which conferred some cross-resistance to toxaphene, chlordane, dieldrin and aldrin. Ticks from Allandale, in addition to being resistant to sodium arsenite, BHC, toxaphene, chlordane, dieldrin and aldrin were highly resistant to DDT. DDT resistance conferred a cross-resistance to Dilan.

The organo-phosphorus insecticides tested, malathion and diazinon, were equally effective against all ticks.

In the present study, resource partitioning by natural conspecific size variants (small and large) of ladybird, Menochilus sexmaculatus (Fabricius) females, in response to varying prey densities was assessed using functional and numerical responses as measures of prey density. The prey provided was small (second) and large (fourth) instars of Aphis craccivora Koch. Results revealed that under choice condition, small and large females of M. sexmaculatus consumed higher number of small and large instars, respectively. Small females exhibited a modified Type II functional response on small aphid instars and a Type II functional response on fourth aphid instars. Large females exhibited a Type II functional response when provided either second or fourth aphid instars. Numerical response in terms of numbers of eggs laid by both the females increased with increase in the density of either of the aphid instars. However, in small females, oviposition had a positive correlation with the numbers of small and large aphid instars consumed; being strong for the small aphid instars. While in large females, oviposition was positively correlated with the numbers of large aphid instars consumed and not small aphid instars. It therefore seems that intraspecific resource partitioning in M. sexmaculatus occurs prominently in large females than the small females.

An account is given of glasshouse experiments in Jamaica to determine the effects of agronomic practice on the fecundity of the sugar-cane pest Saccharosydne saccharivora (Westw.). Eggs (up to one egg per ovariole per day) develop throughout adult life. On young vigorous plant cane the pre-oviposition period was 5·3 days; egg production was highest during the first six days of the oviposition period and declined markedly after 12 days. Mean daily egg production per female over 12 days was taken as an index of fecundity.

The effects of fertiliser application (ammonium sulphate and potassium chloride), wet and dry water regimes, variety (B41227, B42231 and B4362) and crop cycle (plant and ratoon cane), all at different stages of crop development, were observed in four series of experiments involving 1 000 female S. saccharivora. Potassium (K2O) and phosphorus (P2O5) per cent lamina dry matter varied comparatively little, but nitrogen content declined with the age of the plant, increased with application of ammonium sulphate, and was unaffected by crop cycle or variety. Egg production was highest on young cane (up to a mean of 12·0 eggs per female per day), but declined on older cane; it increased with the application of ammonium sulphate but was unaffected by potassium chloride. A direct linear correlation between egg production and the nitrogen content of the leaf (r2 = 0·69, 0·81, 0·52 and 0·69 in series I–IV, respectively) suggested a causal relationship. The pre-oviposition period lengthened and the proportion of females failing to lay any eggs increased in the absence of fertiliser and with increasing plant age. Variation in leaf nitrogen under field conditions could affect egg production.

The development of infestations of Pseudaulacaspis pentagona (Targioni-Tozzetti) on passion fruit vines in Western Samoa was monitored at two sites over a period of 20 months, during which the aphelinid parasitoids Encarsia berlesei (Howard) and E. diaspidicola (Silvestri) were released. All vines were rated for P. pentagona infestations, and the female scale insects were counted on selected vines. At one site, the numbers of P. pentagona built up to over 10 000 adult females per vine before the parasitoids became established, and within one year 50% of the vines died. At the other site, where vines survived, an endemic coccinellid predator, Sticholotis quadrisignata Weise, kept populations below 3000 females per vine until the parasitoids became established. Biological control of P. pentagona was achieved at both sites eight months after the parasitoids were introduced. A model for interaction of P. pentagona and parasitoids predicted higher levels for parasitization than revealed by microscopic examination.

A range of insecticides were tested on a resistant strain of bed-bugs (Cimex lectularius L.) from Israel. Resistance was restricted to organophosphorus compounds. Only some of the phosphorothioate compounds were involved, but there was no simple indication of the resistance mechanism on basis of structure of the compounds.

Nine malathion analogues were tested on the bed-bugs, and relative levels of resistance to them compared with insect strains specifically resistant to malathion. Distinct differences in the bed-bug spectrum suggested that a carboxyesterase was not solely responsible for resistance. This was further supported by the ineffectiveness of triphenylphosphate against malathion-resistance in the bugs.

The F1 progeny from reciprocal mass crosses were tested with malathion. Their response, in both cases, resembled the susceptible type, indicating a recessive autosomal character, a result unique in organophosphorus-resistance. Tests on F2 and backcrosses indicated that a single gene was responsible. Results using fenchlorphos were quite similar and probably the same gene (and mechanism) is involved.

The choriothete of Glossina austeni Newst. was examined in dissections and in histological sections. The choriothete is a highly modified invagination of the anteroventral wall of the uterus forming a tongue-like organ broadly attached to the floor of the uterus. Secretory cells in the choriothete epithelium produce a mucoprotein which finds its way onto the surface of the choriothete through pores in the cuticular intima. The mucoprotein serves as cement to fasten the chorion to the surfaceof the choriothete. Muscles in the choriothete maintain a tension on the ohorion and aid in the removal of the chorion when it is torn by the egg-tooth of the first-instar larva.No evidence was obtained which suggested that the choriothete served a similar function during larval ecdyses.

The following notes consist of corrections and additions to my previous papers on African Culicidae. Several errors have become apparent, due either to carelessness or insufficient study of the material available, or insufficiency of the material itself. These are corrected. One or two apparently new species have been received and are now described ; the description of one or two others, owing to the scanty material and doubtful systematic position, is left for a future paper.

A flight mill is described which permits the automatic measurement of flight duration, speed, periodicity and wing-beat frequency.

Bread and durum wheat varieties varying in wheat stem sawfly resistance were sown at different densities in northern Syria for two seasons to examine the effect of density on plant characteristics related to infestations of the wheat stem sawflies Cephus pygmeus (Linnaeus) and Trachelus spp. Plants sown at low densities had a longer interval between developmental stages and had higher stem solidity than those sown at high densities. Stem solidness was negatively correlated with the percentage of sawfly-infested stems. Plant height and grain yield were neither strongly nor consistently correlated with wheat stem sawfly infestation but were influenced by variety and density. These results differ from those of previous studies in North America where widely spaced plants suffered higher infestations than did closely spaced plants. Results of our study suggest that stand density should be considered when recommending wheat stem sawfly-resistant wheats to farmers in west Asia and North Africa and when designing screening trials for wheat stem sawfly resistance in the field.

The influence of the lepidopteran stem borer Scirpophaga incertulas (Walker), the most important pest of deepwater rice (Oryza sativa) in south-east Asia, on plant and grain yield was investigated in Bangladesh during 1982–85. Four mechanisms of crop loss were identified: (i) deadhearts at the vegetative stage, (ii) loss of damaged but apparently healthy stems in flood water, (iii) white-heads at the reproductive stage and (iv) the effect of late season stem damage on panicles. A great proportion of damaged stems was not visible and damage symptoms were found to be an unreliable indicator for the assessment of borer activities in the field, and did not represent the actual yield loss. Stem damage had a negative influence on the stem density, with reduced panicle density and grain yield. Stem borer damage also seemed to reduce the elongation ability of the rice stem causing them to rot. Late season stem damage reduced the number of filled grains, mean grain weight and panicle weight and increased grain sterility. These effects were related to severity and position of damage. The average estimated yield loss due to S. incertulas was about 17% which took place during the last 11 weeks (from flood peak to crop maturity) of the deepwater rice season (32 weeks).

The limitations of the use of apparent density in estimating trypanosomechallenge are discussed, and it is concluded that such estimates should be based on the feeding portion of the tsetse population, its activity in relation to a given host, the total period of feeding activity (or parts thereof) as the unit of time, and the trypanosome infection rate.

A method of investigating the diurnal feeding activity of Glossina pallidipes Aust. in the late dry season at Eekomitjie, in the Zambezi Valley in Southern Rhodesia, is described. A black ox was tethered daily under a large tree from before dawn until after dusk. Only flies that engorged on the ox were caught; the time of capture and sex of each fly was recorded, and the fly then marked and released. Catches were made on 15 separate but not consecutive days between 21 October and 30 November, 1959.

Diurnal activity extended from 0445 to 1845 hr., there being a small earlymorning peak, reduced activity over the midday period, and a comparatively large evening peak. Climatic factors were recorded but no conclusions could be drawn about their separate effects on activity.

Accidental and intentional global movement of species has increased the frequency of novel plant–insect interactions. In Patagonia, the European woodwasp, Sirex noctilio, has invaded commercial plantations of North American pines. We compared the patterns of resin defenses and S. noctilio-caused mortality at two mixed-species forests near San Carlos de Bariloche, Argentina. We observed lower levels of resin flow and higher levels of mortality in Pinus contorta compared with Pinus ponderosa. In general, S. noctilio attacked trees with lower resin compared with neighboring trees. Resin production in P. ponderosa was not related to growth rates, but for P. contorta, slower growing trees produced less resin than faster growing conspecifics. For all infested trees, attack density and number of drills (ovipositor probes) per attack did not vary with resin production. Most attacks resulted in one or two drills. Attack rates and drills/attack were basically uniform across the bole of the tree except for a decrease in both drills/attack and attack density in the upper portion of the crown, and an increase in the attack density for the bottom 10% of the tree. Planted pines in Patagonia grow faster than their counterparts in North America, and produce less resin, consistent with the growth-differentiation balance hypothesis. Limited resin defenses may help to explain the high susceptibility of P. contorta to woodwasps in Patagonia.

Dryocosmus kuriphilus (Hymenoptera: Cynipidae) is a global invasive gall wasp and a pest of chestnuts (Castanea spp.). A study of the Chalcidoidea parasitoid community of D. kuriphilus was undertaken over two years, from March 2017 to March 2019, at 15 sites in south and northwest Spain (Málaga and Galicia regions). More than 18,000 galls were collected, and 1153 parasitoids belonging to 22 species of seven chalcidoid families, plus two individuals of an inquiline Cynipidae, Synergus facialis, emerged. Richness was higher in the Málaga region, with 20 species, while 17 parasitoids and one inquiline were identified in Galicia. The parasitism rate of native chalcid parasitoid species in both regions was low. Eupelmus urozonus and Mesopolobus lichtensteini were the most abundant native species. Mesopolobus tibialis was a dominant species in south Spain, while Ormyrus pomaceus was a dominant species in northwest Spain. Our results revealed the existence of a sub-community of univoltine, probably host specialized, parasitoids in south Spain, which overwinter in galls, exhibiting a similar life cycle to Torymus sinensis. These species were Torymus notatus, Aulogymnus bicolor, Aulogymnus obscuripes and Aulogymnus balani. Data on the recovery of T. sinensis after release in the south Spain region show it to be well established, but its numbers are still low in northwest Spain.