The willow sawfly, Nematus oligospilus (Förster), is a pest in Salix commercial forests and has been reported worldwide. Female adults must recognize a suitable host plant to oviposit, since her offspring lack the ability to move to another host. We evaluated the effect of conspecific herbivory on the oviposition choices of N. oligospilus females by providing damaged (DP) and undamaged (UP) plants of Salix humboldtiana, a native willow from South America, as oviposition substrates. Local and systemic effects were studied. For the local treatment, a twig from the DP with damaged leaves was contrasted to a twig from a UP in dual choice experiments. For systemic treatment, a twig from the DP with intact leaves was contrasted to a twig from a UP. We estimated the use of olfactory and contact cues by comparing volatile emission of DP and UP, and by analysing the behaviour of the females during host recognition after landing on the leaf surface. In the context of the preference–performance hypothesis (PPH), we also tested if oviposition site selection maximizes offspring fitness by evaluating neonate hatching, larval performance and survival of larvae that were born and bred on either DP or UP. Our results demonstrate that previous conspecific herbivory on S. humboldtiana has a dramatic impact on female oviposition choices and offspring performance of the sawfly N. oligospilus. Females showed a marked preference for laying eggs on UP of S. humboldtiana. This preference was found for both local and systemic treatments. Volatile emission was quantitatively changed after conspecific damage suggesting that it could be related to N. oligospilus avoidance. In the dual choice preference experiments, the analysis of the behaviour of the females once landing on the leaf surface suggested the use of contact cues triggering egg laying on leaves from UP and avoidance of leaves from DP. Furthermore, 48 h of previous conspecific feeding was sufficient to dramatically impair neonate hatching, as well as larval development and survival, suggesting a rapid and effective reaction of the induced resistance mechanisms of the tree. In agreement with the PPH, these results support the idea that decisions made by colonizing females may result in optimal outcomes for their offspring in a barely studied insect model, and also opens the opportunity for studying tree-induced defences in the unexplored South American willow S. humboldtiana.

Resistance of cocoa to Planococcoides njalensis (Laing) was assessed in the laboratory in Ghana by rearing the mealybug from birth until death on seven cocoa progenies, and determining survivorship, duration of reproduction, gross reproductive rate and live weight. Field evaluation was by sampling both P. njalensis and Planococcus citri (Risso) on the tree trunks and in terminal buds. Progenies 85D/176A × M7/537 and T12/116 × T62/977 were judged the most resistant using the parameters determined in the laboratory. The resistance factor is attributed to antibiosis. The mealybug populations in the field did not show any significant differences among the progenies, but the trend followed the laboratory results. It is suggested that the laboratory method reported here is adequate in assessing resistance, has the advantage of being faster than the field technique and can be used in combination with existing methods for assessing cocoa progenies for resistance to the virus disease.

The work described below forms part of an investigation to determine the residual toxicity of DDT when applied to the surface of materials commonly used in the construction of buildings. the bed-bug (Cimex lectularius, L.), because of its wide distribution and habit of infesting surfaces, either exposed or hidden, is an eminently suitable subject for such an investigation. In order to compare the residual toxicity of different surfaces after treatment with DDT, it was considered an essential preliminary step to ascertain whether or not the biological condition of the insect influenced its resistance to the insecticide. The present investigation was, therefore, undertaken to establish any possible variations in resistance which could be correlated with one or more of the following biological factors:— 1. starvation for different periods; 2. sex; 3. stage in the life-history; 4. temperature.

Air temperatures estimated by partial thin plate spline interpolation, or from the ‘nearest station’ (Voronoi polygon method), were used to model the phenology of three pests of horticultural crops throughout England and Wales. Temperatures for a particularly hot (1976) and a particularly cold (1986) year were interpolated to a grid resolution of 1 km. Estimates were made of the timing of spring emergence (Cecidophyopsis ribis (Westwood)), the maximum number of generations completed during the summer (Plutella xylostella (Linnaeus)) and the numbers of days when mating was possible (Merodon equestris (Fabricius)). The relative accuracy of the two temperature estimation methods was compared using jack-knife cross-validation. For C. ribis and P. xylostella, modelling with interpolated temperature input data was more accurate than using data from the ‘nearest station’. Of the three phenology models used, the one that relied on an activity threshold (M. equestris) was the most sensitive to both types of input data. Spatial variability in the activity of M. equestris adults was investigated in the two main areas (south-west peninsula and Lincolnshire) where its host crop (Narcissus) is grown. Modelling at cruder scales (up to 25*25 km) masked local variation, but the degree to which this was important varied from region to region and over time, as did the geography of the variability itself. The results indicate that interpolated data, computed to a resolution of 1 km using the UK synoptic network, have the potential for wider use within agricultural decision support systems for horticultural crops.

In an intensive study, begun in 1955, on the biological control of Pseudaulacaspis pentagona (Targ.) and Pulvinaria psidii Mask. on oleander (Nerium oleander) in Bermuda, several species of COCCINELLIDAE were successfully established, but none developed a population sufficient to control either scale. The failure of these apparently suitable species of Coccinellids was therefore investigated. It seemed possible that insectivorous lizards, which are very abundant everywhere, might be responsible.

Dissection of a number of lizards, Anolis grahami, and A. leachi, in the autumn and winter indicated that at both these times their effect on the natural enemies of scale insects in general and of Pseudaulacaspis pentagona and Pulvinaria psidii in particular, was considerable. Both Coccinellids and Hymenopterous parasites were eaten in large numbers. A surprising number of very small insects including ants, was eaten, and although a number of the insects eaten are harmful, on balance it would appear that, particularly with regard to the biological control of scale insects, the elimination from Bermuda of these lizards, which are introduced species, would be beneficial.

Experiments are being carried out to test this, and the introduction of predacious birds, particularly that of the Trinidad kiskadee, Pitangus sulphuratus, is planned.

The current case study concerns evaluation of the life history of an insect species living in a demanding habitat, namely a xylem-feeder Aredolpona rubra (Linnaeus) (Coleoptera: Cerambycidae) representing the wood-feeding guild. Growth rate, development time and body size at maturity were studied at different temperature regimes with discreteness of insect growth pattern, associated with moultings, taken into account. Moreover, the temperature effect on reproductive strategy of females was tested, and the general life history was compared with available data within the wood-feeding guild. The results show that: (i) the growth of A. rubra is slow but compensated by prolonged development; (ii) size dimorphism is probably caused by the longer development time of females; (iii) fecundity is at least partly determined by the temperature experienced during the egg-laying period; and (iv) interspecific comparisons reveal that the life strategy of a wood-feeder depends on the niche occupied within the tree, whilst its breeding strategy (whether capital or income) is controlled at a taxonomic level. Control of all the main life history traits at one time provided a unique opportunity to understand the selection pressures on A. rubra species. Moreover, comparison within a feeding guild broadens this context and identifies the sources of heterogeneity in the ‘inside-wood’ habitat. The knowledge so gathered may be applied to pest control in forestry science, as well as to the conservation of rare and endangered insect species living within trees.

Mr. C. C. Gowdey, the Government Entomologist of Uganda, is to be congratulated upon the number of interesting forms which he has forwarded to this country for identification from time to time. Many of the species, if not all, are of economic importance, and, judging by their numbers, must have sorely taxed the plants upon which they were found.

Recent taxonomic studies have recognised that Lygus pratensis (L.) consists of several species and other workers have shown that the Tarnished Plant Bug of N. America is L. lineolaris (P. de B.), a species confined to that continent. Although it is impossible to be certain what species is referred to in all of the earlier works on biology and pest incidence of L. pratensis in the Palaearctic region, evidence is given which shows that L. rugulipennis Popp. is the more important pest in this region and it is to this species that the name European Tarnished Plant Bug should be applied. Observations on the life-cycle of L. rugulipennis in England have been carried out and they show that there are normally two generations per year; the second generation becomes adult in the autumn and overwinters in this stage, egg-laying occurring the following spring. This agrees in general with that previously described for L. pratensis, sens. lat.

A new species of larch-feeding sawfly, Pristiphora glauca Benson, was first observed in 1950. The activities of this insect appear to be confined to the spring and early summer, and it would appear that it is one of the least widespread of the larch sawflies.

Notes on the biology of this species, including larval descriptions, are given, and field characteristics and distribution discussed. Differences in feeding habits from those of Pristiphora wesmaeli (Tischb.), with which it may be confused, are mentioned.

Towards the end of 1931 a study of the eggs of Anopheles mosquitos was commenced, primarily with a view to establishing any characters in the egg which may prove useful in differentiating closely allied species, and in particular those suspected of being concerned in the transmission of malaria.

The eggs of ten species of Anopheles are described and figured below : mauritianus var. ziemanni, Grünb., implexus, Theo., pharoensis, Theo., theileri var. hancocki, Edw., christyi, N. & C., gambiae, Giles (costalis, Theo.), transvaalensis, Carter, funestus, Giles, marshalli, Theo., and moucheti, Evans. Of these the writer has had the opportunity of examining specimens of Anopheles gambiae and funestus from four different regions in Uganda, namely, Kampala (3,900 ft.), Jinja (3,800 ft.), Mbale (4,000 ft.) and Fort Portal (5,100 ft.), and no local variations were observed. The eggs of two species dealt with in this paper have been previously figured by workers in other parts of the world. Edwards (1921) reproduced a drawing by Patton of the eggs of Anopheles gambiae (costalis) from Arabia, and Theodor (1924) published a drawing of those of A. pharoensis from Palestine. Both illustrations show eggs which in general structure are very similar to those of the same species in Uganda ; the sculpture of the membrane is not figured. Individual variation within the eggs of a single adult was found to be constant in the case of A. marshalli, the three forms figured being represented in each of the three batches examined.

Ixodes ricinus is the common tick infesting farmstock in Wales. Dermacentor reticulatus is recorded on cattle and sheep on two farms in N. Cardiganshire.

I. ricinus is widely distributed in the four major grassland zones of N.W. Cardiganshire. The most extensive areas of tick infestation are found on the marginal and hill farms. In lowland areas, except on extensive stretches of marshland, infested pastures are confined to isolated tracts of badly managed or poorly drained land. Infested grazings are invariably “rough” and contain one of the following plants as dominant: Festuca spp., Agrostis spp., Molinia caerulea, Nardus stricta, Pteris aquilina or Juncus spp. The degree of infestation of cattle depends on the relative area of the available grazing land colonised by the tick. Continuous stocking of infested pastures results in heavy infestations and vice versa.

Bovine piroplasmosis is the major tick-borne disease in N.W. Cardiganshire and predominates in the lowland districts. Outbreaks of the disease on marginal and hill farms are generally infrequent. Reasons are suggested for this phenomenon. Tick pyaemia is confined to lambs on hill grazings. The incidence of this disease is low.

The distribution of the tick in Wales and the border counties of Hereford and Salop shows a general relationship to areas of rough grazing. The tick is widespread in the western counties and is almost absent in the border counties. Radnorshire and Breconshire are interesting in that they have few infested farms in relation to the extensive nature of the “rough” grazing. A survey has also been conducted of the incidence of bovine piroplasmosis in Wales.

Camponotus compressus, the common black ant (fig. 1), is one of the most abundant and best known species of ants in South India. The worker is a large jet-black ant ranging in length from 6 to 16 mm. with moderately large eyes, brownish legs and antennae and a prominent shining abdomen. These ants live in enormous communities, travelling long distances from their nests, and are active at all times of day and night. Though ordinarily of a peaceful disposition, when alarmed or disturbed they may display a tendency to be quarrelsome.

Trissolcus basalis has been used as a biological control agent of its main host, Nezara viridula, in many countries. However, estimations of its functional and numerical responses in the field are lacking. We estimated the density of N. viridula eggs, the proportion of parasitized N. viridula eggs, and the number of T. basalis adults/trap in the field. We transformed relative parasitoid density to an absolute density, and estimated the parasitoid's attack rate, a, and the mutual interference parameter, m, in two ways: following Arditi & Akçakaya (1990) and using the Holling–Hassell–Varley model with two iterative techniques. The attack rate estimated by both methods were a=1.097 and a=0.767, respectively. Parameter m varied less between methods: m=0.563 and m=0.586, respectively, and when used to calculate the number of parasitized N. viridula eggs per m2, differences with the observed values were not significant. The numerical response of T. basalis was affected by the sex allocation of their progeny and the proportion of adult parasitoids trapped decreased with field parasitoid population density. Theoretical models show that 0<m<1 is a stabilizing factor and previous re-analysis of field data showed a mean m value of 0.8. The Holling–Hassell–Varley model leads to a flexible description of the functional response allowing to predict acceptable weekly host parasitism. The pre-imaginal parasitoid survival and the change in sex ratio as a function of parasitoid density adequately describe the numerical functional response of the parasitoid.

Survival, size and development time were measured for larvae of Lucilia cuprina (Wiedemann) reared in artificially induced strikes on sheep. Between 477 and 18 000 eggs or larvae were implanted in the fleece of 42 sheep. Survival was found not to depend significantly on implant numbers. Size and development time were significantly but only weakly dependent on implant numbers. These results contrast markedly with L. cuprina's performance on carrion.

“Gammexane” and DDT, have many advantages over arsenic as tick killing agents. “Gammexane” dips have been used successfully to control the one host arsenic-resistant blue tick, B. decoloratus (Koch) but these dips have not been fully investigated for the control of two- and three-host ticks. The control of the three-host bont tick, A. hebraeum, a vector of “heartwater”, a disease of cattle, sheep and goats, is of great economic importance to South Africa. Larvae and nymphs seem to occur on cattle to a lesser degree than adults, but each stage shows a definite preference for particular sites on the host. For this reason, control measures have to be mainly directed against the adult stage. The effect of “Gammexane”, DDT and arsenical dips, and combinations of these, has been investigated, by making weekly counts of adults on treated and untreated groups of animals. Dipping has been compared with spraying, and the results have been examined in the light of chemical analyses and biological tests with the same samples. The experiments were spread over two consecutive years.

Preliminary experiments indicated that all treatments markedly reduced numbers of male bont ticks on the cattle. Weekly arsenical treatments with 0·16 per cent. As2O3 either by dipping or spraying did not reduce the numbers of females, nor did a composite dip-wash of 0·16 per cent. As2O3 and 50 p.p.m. gamma isomer. Dipping in 50 p.p.m. gamma isomer gave slightly better results against females than the above treatments. Encouraging results were obtained by spraying cattle with freshly diluted wash containing 50 p.p.m. gamma isomer, but dipping in 100 p.p.m. also gave satisfactory results. The relative ineffectiveness of dipping as compared with spraying, was found to be due to the loss of biological activity of hexachlorocyclohexane in dipping tanks, where complicating pollution factors appeared.

The results of the preliminary experiments were largely confirmed by the second series. Males always outnumbered females in collections where the ticks were removed week by week from cattle. The collections were taken to represent the rate at which cattle became re-infested, and formed a basis on which to gauge the effectiveness of treatments. Males increased in numbers week by week on other untreated control groups of cattle, and eventually greatly outnumbered the females. This suggested that males remained on the hosts longer, and were recorded more than once in the consecutive weekly counts.

All treatments reduced the numbers of males. Weekly treatments in 0·16 per cent. As2O3 did not reduce the numbers of females, nor did it prevent them from engorging. Some females laid after removal from cattle so treated but the eggs were sterile, whilst females in a similar state of engorgement, removed from untreated animals, laid fertile eggs. Arsenical treatments should thus eventually control bont ticks.

All “Gammexane” treatments appeared more effective than the arsenical treatments. Fresh dilutions of dispersible pastes and powders in the form of sprays gave better results than dipping in the same preparations at comparable concentrations. This was due to a loss in biological activity of the hexachlorocyclohexane as the washes became dirty with use in dipping tanks. This factor makes chemical determinations of dip-washes, based on total hydrolysable chlorine, of little value, unless these data are correlated with some suitable biological test. The addition of 0·03 per cent, copper sulphate in the wash did not prevent the loss of biological activity.

Oil emulsion dips, which were known to show a drop in the gamma isomer content with use in dipping tanks, were kept at the desired concentration and biologically active by adding fresh dip each week. In such cases both dip- and spray-washes gave satisfactory results when used at 100 p.p.m. gamma isomer. A combination of 50 p.p.m. gamma isomer and 0·16 per cent. As2O3 used as a dip-wash was not satisfactory in reducing the number of bont ticks, and little better than a fresh spray of 50 p.p.m. gamma isomer alone. The striking results given by a combination of a dispersible powder spray of 50 p.p.m. gamma isomer and 0·1 per cent. p,p′ DDT might be due to persistent action or repellent effect.

Arsenic is a stable substance and has been used for many years in dipping tanks to control ticks. It has disadvantages and in the case of the bont tick many females remained attached to the hosts when treated weekly in arsenic, although the engorged females laid sterile eggs. “Gammexane” preparations when used at 100 p.p.m. gave satisfactory results. These preparations, however, lost their biological activity in dipping tanks, and the best results were obtained when they were applied to cattle as fresh sprays.

The descriptions of new, and determinations of old, species of Anoplura and Mallophaga presented in this paper are based on a small collection of these ecto-parasitic insects taken from mammals and birds of the Egyptian Sudan and other North and West African localities. The collection was made by variouscollectors, as indicated for each species, and was submitted to us by Mr. Guy A. K. Marshall, Scientific Secretary of the Entomological Research Committee (Tropical Africa) of the British Colonial Office.

This short review is incomplete in so far as it deals only with the material received by the Imperial Institute of Entomology for identification and that which is contained in the collections of the British Museum. A list of the species unknown to me is given at the end of the paper.

Nine new species and one new variety are described.

A method is described of applying even deposits of insecticide to leaves without detaching the leaves from the plants. The insecticide is sprayed by hand from an air-operated paint-spray gun under controlled conditions. Using this method for applying the insecticide, the persistence of DDT on living leaves and on glass plates was investigated.

In 1935 during entomological investigations related to an outbreak of jungle yellow fever in Restrepo, Colombia, I captured a female Anopheline which shows morphological details justifying its description as belonging to a new species of a new subgenus. I also found specimens of a new species of Goeldia. These two species are described in the following pages.

Metaphycus flavus (Howard) (Hymenoptera: Encyrtidae) is a facultatively gregarious endoparasitoid of soft scales (Hemiptera: Coccidae). When it develops in superparasitised hosts, the larvae often attack and consume brood mates six or more days post oviposition. Under our laboratory conditions (25±1°C and 14 hours of light followed by 18±1°C and ten hours of darkness in 50–70% R.H.), M. flavus eggs hatched three days after oviposition. Measurements of the mandibles and tentorium indicate there are four larval instars, and M. flavus reaches the fourth instar by day six post oviposition, and pupates on day eight. Thus, cannibalism among M. flavus larvae occurs during the fourth instar. During this instar, M. flavus larvae separate from their attachment to the scale cuticle, to which they were tethered by a respiratory structure during the previous three larval instars. Once detached, they are free to move within the scale, which increases the probability of larval encounters and aggressive behaviours. Moreover, the mandibles of the fourth instar are better adapted for fighting than are those of the first three larval instars, since they are larger and more sclerotized. The cranium and mouthparts of M. flavus have four different types of sensory organs, some of which are almost certainly olfactory, an unexpected function for a larva that presumably is surrounded by an aqueous medium where gustatory sensilla would seem to be more appropriate. The cranium also bears two pairs of what appear to be secretory pores.