Ephialtes brevicornis (Grav.) has been found to parasitise the prepupal stage of Plutella maculipennis (Curt.) under laboratory conditions.

A general description of the life-cycle of E. brevicornis on P. maculipennis is given and it is found to occupy 16 days from egg to adult at 20°C. and a R.H. of 60 per cent. Comparative descriptions are given of the five larval instars. The egg is also described.

Onions are attacked by larvae of Anthomyiid flies from May to August. Two species are concerned, namely the onion fly, Delia antiqua (Mg.), and the bean seed fly, D. cilicrura (Rond.). The onion fly, which in some seasons is mainly univoltine, attacks the crop in June and July. The bean seed fly, which has. 3–4 generations a year, is most injurious to spring-sown onions in May and to summer-sown onions in August. Attack by D. antiqua is the result of the chemotropic response of the species to its host-plants. Attack by D. cilicrura follows the disturbance of the soil during cultural operations in April-May, and occurs again when seed-beds are prepared for August sowings.

The recognition of this complex pattern of attack makes it necessary to reconsider the value of established control measures. The calomel (mercurous chloride) seed-dressing is unlikely to give control of onion fly because its ovicidal efficiency is impaired by exposure to the air during the three months between the sowing of onion seed (end of February) and oviposition (end of May), and by the growth of the plants, which results in the eggs being laid at some distance from the old seed-coat which carries the ovicide. It is also unlikely to have a direct effect on infestation by bean seed fly, because the eggs of this species are not necessarily laid on the seedlings and, in the case of August sowings, the eggs may have hatched before the seed is sown.

Adulticides applied against mosquitoes can reduce vector populations during times of high arbovirus transmission. However, impacts of these insecticides on pollinators and other non-target organisms are of concern to mosquito control professionals, beekeepers and others. We evaluated mortality of Culex quinquefasciatus and Apis mellifera when caged insects were exposed to low and high label rates of four common adulticides (Aqua-Pursuit™ [permethrin], Duet® [prallethrin + sumithrin], Fyfanon® [malathion] and Scourge® [resmethrin]) at six distances up to 91.4 m from a truck-mounted ultra-low-volume sprayer. Honey bee mortality was both absolutely low (<10%) and low relative to mosquito mortality for most products, distances, and application rates. Exceptions were at the high rate of Fyfanon (honey bee mortality of 22–100% at distances ≤61 m) and the low rate of Scourge (mortality <10% for both insects). The greatest ratios of mosquito-to-honey bee mortality were found for the low rate of Fyfanon (30× greater) and the high rate of Duet (50× greater). Aqua-Pursuit and Fyfanon tended to increase mortality of both species at closer distances and at higher application rate; this was related to increased number and size of spray droplets. Wind speed and temperature had inconsistent effects on mortality of mosquitoes only. In this bioassay designed to have insects directly intercept insecticide droplets, mosquito adulticides applied at low rates and at >61 m had limited impacts on honey bee mortality while providing effective mosquito control.

The life-history and bionomics of the Coreid bug, Theraptus sp., which causes premature nutfull of coconuts in Zanzibar, were studied in the laboratory and in the field.

From the various experiments carried out it is concluded that:—

The development of the insect from the egg to the adult took from 26–39½ days depending on temperature and the food available.

The average length of life of the female is 45 days during which time she may produce over 100 fertile eggs.

The primary host-plant of Theraptus is the coconut palm, but the bug readily infests mango, guava, cinnamon and cacao trees when they are fruiting.

The pest will attack and develop successfully on nuts from the newly emerged to the mature ones.

Agents which exert a measure of biological control include the tree-nesting ant, Oecophylla longinoda (Latr.), an internal Strepsipteran parasite, an unidentified Reduviid, two unidentified Hymenopterous egg-parasites and possibly some small ant species which prey on the eggs. Of these, only the ant, O. longinoda, is capable of giving complete protection to the palm which it occupies.

Two kinds of equipment for measuring the reactions of insects to the olfactory stimuli provided by some common components of insecticidal sprays are described. One of these, consisting of a T-tube carrying a current of odorous air across the top and admitting insects up the stem, is new, can be used in the field, and gives rapid and reproducible evaluations. Tests with several species of Diptera showed that technical DDT, diesel fuel oil, and an auxiliary solvent containing methylated naphthalenes are all strongly repellent or contain strongly repellent components. Related species gave similar results with the two kinds of equipment. House-flies (Musca domestica L.) resistant to DDT were less sensitive than normal house-flies. The implications of these findings are discussed.

The distribution of this Tabanid as given by Ansten † is a very wide one. In Africa it occurs from the Transvaal in the south to Egypt in the north, while outside the bounds of Africa it is found in Baluchistan, India, Ceylon, china and Japan. In the Anglo-Egyptian Sudan it occurs fairly commonly in the south, but until this year it had not been recorded from the northern provinces.

A new mealybug injurious to cacao in the Gold Coast was described by Laing in 1944 under the name of Pseudococcus exitiabilis (Bull. ent. Res., 35, p. 91). It was said that it had been reported by the collector, Mr. H. E. Box, to be one of the Coccid vectors of the “Swollen Shoot” virus disease of Cacao. This was later confirmed by Box (Nature, 155, 1945, p. 608).

Changes in adult populations of Haematobia thirouxi potans (Bezzi) were studied in Hluhluwe Game Reserve, Natal, South Africa, between October 1981 and May 1983. While there were no unequivocal seasonal changes in fly abundance, population increases were recorded late spring–early summer and mid–late autumn. Of the two measures of fly abundance, namely the number of flies that emerged from dung pads almost free of other fauna and counts of flies from culled buffalo (Syncerus caffer), the former was correlated with the proportion of nulliparous females in the population (r = 0·82). While the average female completed a minimum of 2·7 ovarian cycles, up to 78% of females during winter were in the 4th or subsequent cycle. The size of flies collected from buffalo and from dung pads showed an overall reduction during the study period and was an important factor in both survival and fecundity. Differences in the preference of flies for buffalo over an Afrikander-Shorthorn cross heifer, were manifested in the sex ratio and proportions of nulliparous females and fed flies.

Detailed descriptions are given of the adults, larvae and pupae of Mallophora media sp.n., Asilidae, which occurs in Trinidad, W.I. The larvae live in the soil and prey upon larvae of Scarabaeidae. The affinities of the new species are discussed.

The alien cynipid wasp Dryocosmus kuriphilus Yasumatsu, 1951 is a serious pest of chestnuts (Castanea spp.) in Japan, North America and Europe, causing fruit losses while inducing galls in buds. While D. kuriphilus galls have a recognizable and roughly invariable globular shape, their size varies, reaching up to 4 cm in diameter. Among other factors, such variation may depend on different climatic conditions in different attacked areas. Here, we sampled and measured 375 D. kuriphilus galls from 25 localities throughout the Iberian Peninsula, including both cold and rainy northern (Eurosiberian) areas and warm and dry central-southern (Mediterranean) areas, to test the effects of climate and geographical location on gall morphology. The analyses indicate that gall mass and volume follow a pattern that can be associated with a climatic cline. In particular, the Eurosiberian galls were smaller than the Mediterranean galls according to differences in climatic conditions. In the southern areas, the greater insolation regime does not allow the chestnut trees to be distributed at lower altitudes, but the high rainfall and humidity regime of the mountain enclaves allow their presence. These conditions of insolation and precipitation seem to influence the morphological characteristics of the galls of D. kuriphilus.

The distribution on cotton plants of the eggs, nymphs and to a lesser extent the adults of Empoasca lybica (de Berg.) was studied on the varieties Bar XL1 and BAJ 7/57 in the Sudan during 1961–64. Counts of jassid nymphs in the process of hatching from eggs buried in the leaf veins showed that hatchlings were most numerous on the third to fifth expanded leaves from the main-stem apex and that most eggs had been laid either close to the point of insertion of the petiole into the leaf lamina or about half-way along the length of the veins on the underside of the leaves. The greatest number of hatchlings was found in the central leaf vein. It was concluded that eggs are most frequently laid in this position on newly expanded leaves at the apices of the main stems or side branches.

The distribution of the early instars on the main-stem leaves was peaked, with maximum numbers occuring on or about the fifth expanded leaf from the apex; a similar distribution with a less prominent peak nearer to the apex leaf was found on side branches. The later instars, being more mobile, had a more even distribution. In the over-all distribution of nymphs on a typical cotton plant, a combination of the patterns found on main-stem and side-branch leaves, the greatest numbers of jassids occurred in the upper half or upper third of the plant. Co-variance analyses showed that the relation between numbers of jassids per zone and number of leaves per zone was not close and that the manner in which the plants were divided into zones for analysis of the relation greatly affected the correlation coefficients obtained.

Regular counts of nymphs and adults on the upper surface of leaves throughout a period of two complete days showed that both nymphs and adults moved to the upper surface of leaves each day between 1400 and 1800 hr. local time and returned to the under surface at about 0300–0400 hr. Neither the environmental factor that stimulated this movement nor the way in which it benefited the insect was clear.

Energy dispersive X-ray spectrometry was used to make quantitative determinations of the elemental composition of plasma-ashed apterous and alate individuals of Rhopalosiphum padi (L.). The aphids were collected as fundatrigenae at various localities in England and Scotland, mostly from their main overwintering host, Prunus padus, but at one site also from P. virginiana. Robust-means principal components analysis of the data confirmed that there were differences, unrelated to source, between the elemental composition of apterae and alatae, with lower concentrations of S, K and Cl in the alatae. There were, however, no clear separations of sources in either morph except between some extreme groups; it is possible that genetic uniformity limits variation in elemental composition and, therefore, the existence of detectable source-related chemoprints in R. padi. Elements that provided some discrimination were S, Cl, Ca, Zn and possibly Al, and, except for S, their mean concentrations were all less than 1% of weight of the sample examined; difficulties in detecting differences at these low concentrations may have prevented detection of source-related chemoprints in R. padi.

The effect of dung burial by the African dung beetle Catharsius tricornutus De Geer on the survival and size of the dung-breeding African fly Haematobia thirouxi potans (Bezzi) was examined in the laboratory at 25°C using 1-litre pads of cattle dung. The experiment included a set of dung pads which were exposed to infrared radiation for 12 h per day to mimic the heating effect of solar radiation. C. tricornutus is a large (1–2-g live weight) dung beetle, and moderate numbers can completely bury dung pads within 24 h of pad colonization. Dung burial was proportional to the number of pairs present (range 0–8 pairs per pad), but the level of burial was reduced in the presence of infrared radiation. Dung pads lost moisture with time, and the rate of desiccation of unburied dung increased with the amount of dung burial and under infrared radiation. Mortality in the immature stages of H. t. potans increased with increasing levels of dung burial and with exposure of pads to infrared radiation. The timing of addition of dung beetles (i.e. before or after egg hatch) did not affect fly survival. At moderate levels of dung burial, fly larvae were killed directly by beetle activity and at high levels of dung burial, fly larvae also perished due to an unfavourable physical environment associated primarily with moisture stress. Infrared radiation killed immature flies and increased the level of moisture stress. There was a low level of survival in dung buried by the beetles under these unnatural laboratory conditions. Stunting of surviving flies was associated with reduced levels of moisture in the core of the unburied dung and was observed when the level of dung burial was >60% in ambient conditions and >40% under infrared radiation.

The work described in this paper has been carried out with two proprietary samples, designated Systox 50 emulsion and E 1059, of a systemic insecticide of which the active ingredient, subsequently referred to throughout as Systox, is a mixture of O,O-diethyl O-ethylmercaptoethyl thiophosphate and its isomer, O,O-diethyl S-ethylmercaptoethyl thiophosphate.

The samples were tested against Aphids for contact and systemic action.

It is concluded that, as a contact insecticide against Aphis fabae Scop, on broad beans, Systox is about equitoxic with paraoxon and so more toxic than schradan and dimefox.

Systox is readily absorbed by the roots of broad bean and cabbage plants from soil, sand and aqueous solutions and the translocated material is very effective as an insecticide against A. fabae on broad bean, and Myzus persicae (Sulz.) and Brevicoryne brassicae (L.) on cabbage.

Applied in this way, Systox is more effective than schradan, dimefox and paraoxon, and about equal to the most toxic compound previously tested, sodium fluoroacetate.

An experiment by the cut tap-root technique confirms these conclusions. A dose of 1 mg. of Systox per kg. of fresh bean-plant tissue gave a complete kill of A. fabae by the 10th day. The same amount of sodium fluoroacetate had previously been shown to give a complete kill in three days.

The plants were carefully watched for signs of damage during the tests. It was concluded that there was a considerable margin between the insecticidally effective and the phytotoxic concentrations.

Systox is also translocated from older to younger leaves of bean and cabbage plants and it may reach concentrations sufficient to kill the Aphids feeding on the untreated leaves. This effect was more consistently obtained in the broad bean than in cabbage plants. In both cases, however, the results were variable.

Solutions of Systox exert a direct fumigant action on Aphids, but there is little evidence that toxic material is transpired by treated plants.

In connection with studies on the control of tsetse flies (Glossina spp.) by insecticides, an investigation was made in Tanganyika Territory of the influence of a number of factors on the distribution of insecticide in woodland and open country. A solution of DDT in oil was disseminated as a coarse aerosol from an aircraft and its behaviour traced by the mortality suffered by caged flies. The test insects were wild-caught Musca (Eumusca) lusoria Wied., which proved more susceptible to the insecticide used than did Glossina. palpalis fuscipes Newst.

In open country, complete kills were obtained with the standard application rate (defined as one run using 10 gals, per minute of a 10 per cent, solution of DDT) for at least three hundred yds. downwind of the line of emission, in all the atmospheric conditions encountered.

Tests of the possibility of treating very thin woodland in comparatively high winds (for aerial dispersals of aerosols) and slightly unstable conditions were spoilt by variations in the emission rate of the insecticide, but it was shown that quite small numbers of twigs upwind provided a considerable degree of protection to the test insects and that the kills in cages completely exposed on the upwind side of trees were considerably less than at corresponding distances downwind in completely open country. There was evidence that in high winds and slightly unstable conditions, penetration through the trees was better than with moderate winds and small inversions, but in both conditions there was mortality behind obstacles.

Preliminary comparisons between the kill in the open and in continuous woodland composed of Acacia xanthophloea showed that in the latter mortality was greatly reduced and did not approach that frequently obtained in practical large-scale experiments in tsetse control. A search was made for factors which would increase the level of mortality.

Increased atmospheric stability caused greater average mortality at the expense of evenness of kill. This was not due solely to decreasing effective swathe width due to lighter winds.

Large natural openings in the canopy assisted the penetration of insecticide in unstable conditions, but in stable air the kill around and downwind of clearings was reduced compared with kills in unbroken woodland.

The principal factor in raising mortality to a generally high level was the summation of sublethal doses due to drifting downwind of the fringes of successive parallel swathes. The highest kill obtained in any of these trials was from summation of three swathes emitted 75 yds. apart, which produced a mean mortality of 84 per cent, for 75 yds. downwind of the third run.

An attempt to cover the whole area of woodland by emitting insecticide in a series of parallel runs, as in actual control procedure, showed that in conditions of low turbulence there yet may be great unevenness in the kill obtained. Mortality varied between 21 and 100 per cent., and this irregularity was almost certainly due to the fact that during each of the runs the wind was almost directly along the aircraft track. Such contingencies are unavoidable, for unsteadiness of wind direction is a constant feature of the stable, non-turbulent conditions in the free air that are needed to permit any substantial kill within continuous woodland.

The relation between these results and those obtained in practical control experiments is discussed. It is concluded that the use of caged insects and a particular type of woodland probably accounts for the comparatively low kills obtained in this investigation, from which, nevertheless, valid conclusions can be drawn concerning the variation in mortality from place to place.

Species of Rodolia Mulsant (1850) are important as predators of mealybugs, some of which are notorious for their injury to plants. Rodolia cardinalis Mulsant is a classical example of a species that has been successfully introduced into several countries against the cottony-cushion scale, Icerya purchasi Maskell. A campaign against the latter, in South India, has be.en in progress for some time, and a number of local Coccinellid predators, collected by the staff responsible for the work, were sent for identification to the Commonwealth Institute of Entomology. The present study is based mainly on this material, and also on that in the British Museum (Natural History). All the known Indian species are redescribed and three new ones added to the list.

The relationship of oviposition to weather, with a standard stimulus (4 per cent. ammonium carbonate), has been tested by a series of 134 exposures of a group of three sheep for one hour. 190 egg clusters were obtained, of which 169 were identified. With the exception of one cluster of L. caesar all were L. sericata.

There was a fairly close correlation (0·586) of oviposition with air-temperature. When the possible effect of other factors was eliminated, the correlation was little affected, showing that temperature was in itself responsible for the variations in oviposition. The lower critical limit of temperature was in the neighbourhood of 56°–58°F.

Solar radiation and oviposition had an apparent correlation, but this was found to be spurious, the effect being due to related air-moisture changes. At temperatures near the lower critical limit, insolation did not increase the oviposition rate, or lower its temperature threshold.

Humidity had an apparent inverse correlation with oviposition, but this also was an indirect effect, due to related temperature changes. Humidity showed a closer correlation when expressed as saturation deficiency than as relative humidity. Evaporation rate from a white atmometer sphere had only a low correlation with oviposition.

It is shown that the partial correlations of both saturation deficit and insolation with temperature effects eliminated, are insignificant, i.e. their apparent effects are due to related temperature changes. The multiple correlation coefficient for temperature humidity and insolation is practically identical with that for temperature.

Independent variations of insolation, i.e. variations not simultaneous with related temperature changes, had a significant effect on oviposition; for a given temperature, a high intensity of insolation was less favourable than a low, and this appeared to be a true insolation effect, and not due to associated humidity changes.

Independent variations of humidity had a suggestive but statistically insignificant effect, humidity tending to be inversely related to oviposition.

The regression of log oviposition on temperature, within the limits of this experiment, i.e. at temperatures up to 72°F., was linear. The slope was not significantly affected by the insolation and humidity factors, the total coefficient being 0·, and the partial coefficient 0·0428. These coefficients are the increase of the log number of egg clusters (plus one) for 1 degree F. increase, i.e. the oviposition rate increased in geometric progression for unit increase of temperature, the value (N+l) for egg clusters doubling itself for 7° increase.

Lygus simonyi has been found to cause serious damage to cotton in Uganda, by sucking the young leaves and apical buds, by retarding the growth of the branches, and by sucking the young bolls.

There are indications that soil and climatic factors are of importance in controlling this insect ; excessive succulence of the plant appears to be one factor associated with severe damage.

This study aimed to evaluate the acaricidal activity of lettuce (Lactuca sativa) extracts against carmine spider mites (Tetranychus cinnabarinus Boisd.) and isolate the acaricidal components. Acaricidal activities of lettuce extracts isolated from different parts (the leaf, root and seed) using various solvents (petroleum ether, acetone and methanol) were evaluated with slide-dip bioassay and relatively high median lethal concentration (LC50) values were detected. Acetone extracts of lettuce leaves harvested in July and September were fractionated and isolated with silica gel and thin-layer chromatography. Consequently, acetone extracts of lettuce leaves harvested in July exhibited higher acaricidal activity than those harvested in September, with an LC50 value of 0.268 mg ml−1 at 72 h post-treatment. A total of 27 fractions were obtained from the acetone extract of lettuce leaves harvested in July, and mite mortalities with the 11th and 12th fractions were higher than those with the other 25 fractions (LC50: 0.751 and 1.258 mg ml−1 at 48 h post-treatment, respectively). Subsequently, active acaricidal components of the 11th fraction were identified by infrared, nuclear magnetic resonance and liquid chromatography/mass spectrometry. Five components were isolated from the 11th fraction, with components 11-a and 11-b showing relatively high acaricidal activities (LC50: 0.288 and 0.114 mg ml−1 at 48 h post-treatment, respectively). Component 11-a was identified as β-sitosterol. In conclusion, acetone extracts of lettuce leaves harvested in July might be used as a novel phytogenic acaricide to control mites.

The silkworms which are found in the largest quantities in Uganda belong to the genus Anaphe (family EUPTEROTIDAE), of which we have three species, Anaphe infracta, Wlsm., A. venata, Butl., and A. moloneyi, Druce. The other species of silkworms which have so far been observed in the Protectorate are Mimopacha gerstaeckeri, Dew., and Hypsoides milleti, de Juan, but these are comparatively rare. This paper deals only with Anaphe infracta.