Cryptotermes havilandi (Sjöst.) is an important pest of domestic timber in West Africa, and in 1957 a study of certain aspects of its biology was made at Port Harcourt, Nigeria.

The alate is positively phototactic on emergence, and the main flights occur at dusk, between 1800 and 1900 hr. Heavy flights continue until 2200 hr., but few alates can be seen after 0100 or before 1600 hr. There is a peak of activity in the drier months of January and February, but flights take place in every month. Emergence for flight is associated with drier atmospheric conditions.

After a change to negative phototaxis, followed by shedding of the wings, the dealates search for a nest site. Tandem behaviour does not occur. The dealates cannot bore into sound wood, and a hole or crack is essential for colony foundation. The entrance to the hole is sealed with material carried in the gut of the insect, according to a fixed behaviour pattern. Dealates seeking to enter wood prefer holes between one and a half and three millimetres in diameter, and cannot use those of less than one or more than five millimetres in diameter. Preference by dealates for particular species of wood was not shown conclusively. There was no discrimination against wood containing lethal doses of borax or Celcure (a proprietary mixture consisting essentially of potassium dichromate, copper sulphate and acetic acid or chromium acetate).

The rate of egg-production, the incubation period, and the duration of the first three instars are recorded. At the rate estimated, egg-production by a physogastric queen could maintain populations in excess of 3,000. Neoteinics are readily produced in isolation from all but the first three larval instars. They may lay eggs from 35 days onwards, and in their first year have much greater fecundity than primary queens.

The economic applications of the observations and experiments are discussed, together with some factors affecting testing of timbers against termite attack.

An account is given of work carried out since that of Wootten & Sawyer (1954) on the pick-up of spray droplets by flying locusts. The same species, Schistocerca gregaria (Forsk.), was used. The values given in their work for the amounts of spray collected were confirmed, but when observations were extended to cover smaller droplets (less than 50-μ. diameter), locusts were found to collect these much less efficiently.

Other factors affecting pick-up were sex (females collected more spray than males) and flying speed (faster-flying locusts tended to collect less spray per unit of distance flown). When the angle of approach of the droplets to the flying locusts was varied between 1 and 11° from the horizontal no difference in the pick-up of spray could be detected.

For droplets between 60- and 300-μ diameter, the dose of insecticide collected by the locusts is given by the formula 9xPC μg. for males, and 11·5xPC for females, when the locusts fly through a concentration of spray of C ml. per cu. m. for a distance P m. and the spray solution contains x per cent, (w/v) of insecticide.

In a continuation of studies of diurnal and seasonal feeding activity of Glossina pallidipes Aust. in thick riverine vegetation at Rekomitjie, in the Zambezi Valley, Southern Rhodesia, flies attracted to a stationary black ox were allowed to become engorged, then caught, marked and released. More flies fed per day in the late dry season (November), and fewer during the rainy season (February), than at other times of the year. The proportions of females amongst flies feeding, and of marked flies recaptured, were greatest in May (77·6 and 20·0 per cent., respectively) and least in November (59·2 and 7·7 per cent., respectively). The diurnal pattern of feeding activity was similar in all seasons, there being a well-marked peak of activity at or shortly before sunset.

The trypanosome infection rate was obtained by dissecting flies caught near the experimental site and was combined with figures for the number of flies attacking the ox to give an estimate of the seasonal trypanosome risk (mean number of infected flies that fed on the ox per day); this was greatest in November and smallest in February.

From comparison of catches off a moving and a stationary ox, two stationary oxen standing together, and two standing out of sight of one another, in each case one being red and the other black, it appears that colour of the bait-animal is not of great importance as an attractant to G. pallidipes unless a definite choice is presented, when flies show preference for feeding on a dark surface.

Two Lepidopterous leafminers have been observed on sweet potato at Koronivia, Fiji. The Gracillariid Acrocercops prosacta Meyr. is the more abundant species in most areas but populations of a Lyonetiid, Bedellia ipomoeae Bradley, reach damaging levels in fields sprayed with dieldrin for control of weevils (Cylas formicarius elegantulus (Summers) and Euscepes postfasciatus (Fairm.)). Such treatment is shown to reduce parasitisation of B. ipomoeae by a species of Apanteles near A. tapatapaoanus Fullaway and of A. prosacta, by another Braconid, a species of Mesocoelus near M. acrocercopsis Mues. However, outbreaks of B. ipomoeae could not be attributed to such reduction. Elimination of ant predation by the dieldrin sprays was more likely to have initiated the outbreaks.

Sprays containing malathion, diazinon, or dieldrin killed larvae, but not pupae, of B. ipomoeae. Outbreaks of B. ipomoeae can probably be prevented by relying on cultural methods to control weevils or by intensifying insecticide applications to control both B. ipomoeae and the weevils.

Some effects of temperature, relative humidity and food supply on the fecundity, length of adult life and rate of development of Necrobia rufipes (Deg.) are outlined.

At 30°C. and 64–70 per cent. R.H., females laid few eggs when supplied with palm kernels as food, whereas when given freshly squashed larvae of Carpophilus dimidiatus (F.) as their only food supply they laid large numbers of eggs.

When Aspergillus spp. commonly found on copra of high moisture content were cultured, conditioned and supplied as the only food at 30°C. and 81 per cent. R.H., newly emerged larvae died within two days. Complete mortality also occurred on palm kernels at 30°C. and 64–70 per cent. R.H., although a few larvae survived for 60 days.

On copra alone, complete development occurred in all conditions attempted, except at 25°C. and 53 per cent. R.H. Development on this food was most rapid at 30°C. and 81 per cent. R.H. (mean period (larva + pupa) 66·5 days). The addition of fishmeal to copra reduced the mean period of development (larva + pupa) at 30°C. and 81 per cent. R.H. to 42·6 days. The shortest mean period of development (larva + pupa) recorded, 37·9 days, was with larvae of C. dimidiatus as food, at 30°C. and 64–70 per cent. R.H. Rapid development was also achieved by adding larvae of N. rufipes to a culture of Oryzaephihis mercator (Fauv.).

Oviposition time (the time from blood-meal to egg deposition) has been investigated in five strains of Aedes aegypti (L.), two being DDT-resistant (from Trinidad and Haiti) and three susceptible (from West Africa (2) and Haiti). All the strains except the two DDT-resistant ones differed significantly from one another in mean oviposition time.

There was a close correlation between mean oviposition time, oviposition period (the over-all period during which eggs are laid) and ‘oviposition light preference’, both the former being greater in the ‘dark-laying’ strains than in the ‘light-laying’ ones. There was a positive correlation amongst four of the strains between degree of DDT-resistance and both mean oviposition time and oviposition period; the fifth, which combined long oviposition time with susceptibility to DDT, was a recently colonised West African strain.

In small mass crosses between two strains differing markedly in mean oviposition time, this character showed no dominance; it appears to be under poly genie control. Evidence is given which indicates that there is no close genetic connection between oviposition time and DDT-resistance. There is also no obvious genetic association between oviposition time and ‘oviposition light preference’.

It is concluded that the observed differences in oviposition time may have come about as a result of DDT selection, but could equally well have been the result of a selective influence exercised by the laboratory environment.

Earlier types of suction sampling apparatus, driven by electric or petrol motors, are briefly reviewed and their disadvantages for work in remote areas indicated. To overcome these a cheap, simple, hand-operated model has been developed and the construction of this is described. However, unlike some of the motorised models, it does not extract all the fauna from the area sampled.

In conjunction with an investigation of the diurnal and seasonal feeding behaviour of Glossina pallidipes Aust. in dense riverine vegetation in the Zambezi Valley, Southern Rhodesia, gorged flies caught on a stationary ox were marked and released and their subsequent resting places recorded. Fallen logs, a rot hole, boles and branches were found to be utilised in the late hot dry season (November), but in the rainy season (February), the cool season (May) and the early dry season (August), flies were found almost entirely on branches. Of the total resting flies observed, 89 per cent, were at heights of 0 to 9 ft., but whereas in November 49 per cent, of resting flies were at heights between 0 and 3 ft., only 10 to 19 per cent, rested at this level in the other seasons. The choice of more deeply shaded resting sites in November is thought to be due to a reversal, at temperatures over 35°C., of a normally positive reaction to light. The resting behaviour did not appear to differ greatly between sexes, although females do not move so readily as do males on to sites other than branches.

In November, a diurnal pattern of resting behaviour was noted. A branch type of site was preferred in the early morning, but a shift to the rot hole and boles was evident during the middle of the day, followed by a return to branches in the evening; there was evidence that flies rested in yet another type of site at night. In May, searches from 1930 to 2100 hr. for flies marked with reflecting paint revealed some on leaves and small twigs.

The tsetse fly population of Block 9 at Shinyanga, Tanganyika, consisting of 40–50 square miles of thorn bush, was studied from 1935 to 1957 by means of fly-rounds with a total length of 30 miles. The mean annual apparent density (A.D.) of Glossina swynnertoni Aust., taken as the geometric mean of the 12 monthly figures, is plotted on a graph covering 23 years, together with data for 1930–36 from another block which, however, is only doubtfully comparable. Four peaks and five troughs occur on the graph of Block 9, the highest value being 18 times the lowest. The history of the natural and artificial events which have occurred in the block are detailed as far as they are known. The minimum A.D. was that of 1938, after a number of wild animals had died of rinderpest; thereafter, the A.D. rose for several years, in spite of certain anti-tsetse measures, and none of the fluctuations subsequent to 1938 can be associated with any natural or artificial event. The amplitude of the fluctuations is small compared with records in the literature for other animal populations, and their occurrence is irregular; the last peak observed was in 1954, but limited observations in 1959 gave catches little, if at all, below those of 1954.

The data were also analysed for seasonal variations. The least monthly mean catch was that of November, the greatest, differing from the least by a factor of only 1·34, that of April. Earlier published accounts of G. morsitans Westw. (based, however, on relatively short periods) give later maxima and greater amplitudes. Annual and seasonal records of the percentage of teneral individuals among male flies and the percentage of females among non-teneral flies are also given, but these data cannot be interpreted at present.

The rate of oviposition of isolated pairs of Tribolium castaneum (Hbst.) on finely divided wheatfeed was measured over the entire adult life at 25°C. and 70 per cent. R.H. It was also measured over a period of seven weeks from the start of oviposition at 30 and 70 per cent. R.H. at 25, 30 and 35°C., respectively, at 70 per cent. R.H. only at 22·5, 27·5, 32·5 and 37·5°C. and at 2 per cent. R.H. at 30°C.

At 25°C. and 70 per cent. R.H. each female laid, on the average, 360 eggs at the rate of 2·5 per day for about one hundred days and then at a decreasing rate for the next hundred days. When this experiment was repeated over a seven-week period, each female laid on average about 3 eggs per day. At 70 per cent. R.H., the optimum temperature for oviposition was about 32·5°C., at which about 11 eggs per day per female were laid over the seven-week period. These rates fell to just over 2 per day at 22·5°C. Only one egg was laid by 15 females at 20°C. At 37·5°C. the rate was about 10 eggs per day initially but it declined to about 3 per day by the end of seven weeks, whereas at lower temperatures the decline in laying was slight. Compared with 70 per cent. R.H., the oviposition rate at 30 per cent. R.H. was almost halved at 25°C., but was only slightly reduced at 35°C. At 30°C. and 2 per cent. R.H., females laid well, averaging over 4 eggs per female per day. The periodic provision of water for drinking at 25°C. and 30 per cent. R.H. depressed oviposition.

The preoviposition period was 2 days at 37·5°C. and increased steadily at lower temperatures to 10 days at 22·5°C. It also varied more between females at low temperatures.

The number of eggs recovered in this work was lower than the number obtained by Park & Frank (1948), who used considerably more food in their oviposition chambers. In this work, some eggs were eaten by the adult beetles. However, the innate capacity for increase of the species calculated on these data is extremely high, and could not be maintained for long because of the cannibalistic habits of this species.

The feeding of the cacao thrips, Selenothrips rubrocinctus (Giard), on cashew, Anacardium occidentale, one of its host plants in Trinidad, West Indies, is considered in relation to the annual period of maximum population increase on this host and to the choice of feeding sites on individual leaves. On trees observed for three years, populations regularly increased during the dry season, from a low level in December and January to a peak in April or May, and then rapidly declined during the wet season. Even when thrips were most abundant, some trees were free from attack, and this could not be attributed to protective morphological features, to specific repellent substances in the leaf, or to chance. S. rubrocinctus was found to feed on leaves that were subjected to water-stress and to breed only on debilitated trees: the evidence suggested that the adequacy of its supply of nutrients depends on the induction of suitable metabolic conditions within the leaf by water-stress.

Both nymphs and adults normally feed on the lower, stomata-bearing surface of the leaf, but in a very humid atmosphere only a weak preference is shown for this surface and if, under natural conditions, it is exposed to insolation by inversion of the leaf, the insects migrate to the other surface. Since the thrips were shown to be indifferent to bodily posture, the observation suggests that their behaviour is governed primarily by avoidance of exposure to undue heat or dryness and only secondarily by the attractiveness of the stomata-bearing surface.

Leaves of cashew tend not to become infested while still immature, and become most heavily infested, if at all, soon after they have hardened. Breeding does not occur on senescent leaves. The positions of feeding thrips are almost random on leaves under abnormal water-stress, but otherwise conform to certain patterns that mainly develop in fixed sequence. On reversal of an undetached leaf and consequent transfer of thrips from one surface to the other, there is no appreciable change in their distribution pattern or the apparent acceptability of the substrate. Changes of pattern were readily induced by injury to the plant during a period of water-stress and less easily, or not at all, when water-stress was low. Injury of areas of the leaf by heat was followed by their colonisation by thrips, and partial severance of branches by increased attack on their leaves.

Leaves detached from uninfested trees invariably became acceptable for feeding within four hours. During this period, leaf water-content declined and the ratios of soluble-carbohydrate content and α-amino acids to fresh-leaf weight fell slightly and rose considerably, respectively. In the field, the latter ratio was invariably higher for infested than for uninfested leaf tissue, even on portions of the same leaf. If the nutrient value of leaf tissue is determined by the rate at which α-amino acids are extractable through a stylet puncture, the observed change in acceptability for feeding following plucking may be accounted for by the increase in α-amino-acid concentration. Feeding that is restricted on any one tree to the margins of local leaf injuries during prolonged high water-stress and totally absent when stress is low can be correlated with an α-amino-acid content in the living marginal tissue that is high or low, respectively. The ability of thrips to establish themselves and breed on leaves of a particular tree in the dry season and their failure to do so on leaves of the same tree in the wet season conforms with the greater or less amino-acid concentration occurring in the leaf at these respective times.

A simple method is described of testing the susceptibility to acaricides of larvae of the cattle tick Boophilus microplus (Can.) in Queensland, Australia, by enclosing them in packets made from rectangular filter papers, folded once and secured along the remaining three sides by spring clips, that had been impregnated with Risella-oil solutions of DDT, dieldrin, or Bayer 21/199 (coumaphos), or with deposits from xylene solutions of Dilan. The response of susceptible engorged adult females to dieldrin was tested similarly. Five out of six experiments showed statistical evidence of repeatability of results in determination of relative DDT-resistance of larvae. There was a slight increase in susceptibility of non-resistant larvae to DDT with increasing age between 7 and 28 days for fresh packets but not for re-used packets. In three out of four tests, re-used packets were significantly more toxic (up to 1·40 times) to susceptible larvae than fresh packets. In one test a loss of toxicity occurred after storage of Bayer 21/199 packets for 23 days. The possible use of this method for measuring resistance in ticks is discussed.

Research on Lepidopterous stem borers of Nigerian cereals began in 1951. Preliminary surveys finished in 1954 and from 1955 to 1961 the author studied these pests in Northern and Western Nigeria.

Guineacorn (Sorghum vulgare) and millet (Pennisetum typhoides) are the most important cereal crops in Northern Nigeria, and maize (Zea mays) is the only cereal of any importance in Western Nigeria. The crops are sown early in the wet season, which alternates with a dry season of two to seven months, and mature in three to five months. They are cultivated by hand and few farmers grow more than one acre of any one cereal.

The host ranges of all the known species of Nigerian cereal stem borers (viz., Busseola fusca (Fuller), Sesamia calamistis Hmps., S. penniseti Tams & Bowden, S. poephaga Tarns & Bowden, S. nonagrioides botanephaga Tams & Bowden, Manga basilinea Bowden, Coniesta ignefusalis (Hmps.), Chilotraea sp. ? argyrolepia (Hmps.), Chilo sp. ? phaeosema, Martin, Maliarpha separatella Rag. and Eldana saccharina Wlk.) are summarised and their distribution in Nigeria and relative importance there are discussed.

B. fusca and Coniesta ignefusalis are the most important stem borers of guineacorn and millet, respectively, and detailed accounts of their life-cycles and seasonal cycles are given, together with observations on adult activity, light-trap catches, larval migration, larval morphology and the effects of larval feeding patterns on plants of guineacorn and millet. Differences between the pupae of the three Noctuid genera (Busseola, Sesamia, Manga) and all stages of C. ignefusalis are illustrated. Some information on the biology of S. calamistis, S. poephaga and M. basilinea is also given.

At Samaru, the life-cycles of B. fusca and G. ignefusalis are completed in about two months under field conditions and in the absence of diapause. Three generations develop during the growing season, larvae of the third entering diapause until the next season. Many diapause larvae survive the dry season in crop residues, and the local practice of stacking stems for later use in building, etc., ensures reinfestation of subsequent crops, particularly near villages. The diapause ends between late April and early June, so that adults of the diapause generation emerge about three weeks after millet and guineacorn have germinated. Experiments indicate that diapause is terminated when larvae are provided with moist food or drink water. The relative abundance of B. fusca and C. ignefusalis in guineacorn, millet and maize largely reflects host selection by ovipositing females. C. ignefusalis lays freely only on millet and is therefore mainly confined to this crop, whereas B. fusca, though favouring guineacorn, also lays on the other two crops. Experiments indicate that more eggs are laid on larger plants.

Early millet and maize are harvested before borer populations reach their highest level. Guineacorn tolerates the considerable damage done by the high populations present at the end of the season but late millet and second-crop maize do not. Any factor hindering normal crop development tends to increase the damage done.

A provisional list of 14 primary parasites, three hyperparasites, one predator and four diseases is given. Tetrastichus atriclavus Wtstn., Apanteles sesamiae Cam., and Pediobius furvus (Gah.) were always present on B. fusca at the end of the season. Syzeuctus sp. was the most important parasite of C. ignefusalis and was regularly reared from diapause larvae, and other common parasites of this species later in the season were Sturmiopsis parasitica (Curran), T. atriclavus and Hyperchalcidia soudanensis Steffan. The over-all rate of parasitism seldom exceeded 10 per cent, of all larvae and pupae collected. Bacillus thuringiensis killed many diapause larvae of B. fusca and was the most important disease recorded.

The results of experiments relating yields to stem-borer attack in maize, early millet, late millet and guineacorn are presented and discussed. Early-sown maize suffers little damage but second-crop maize at Ibadan suffers losses of stand which, in local farms, generally exceed 20 per cent. In experiments, loss of stand did not always result in loss of yield, and evidence is presented that, under certain conditions, loss of stand is compensated for by the production of heavier cobs. At Samaru, the development of single larvae of B. fusca in otherwise healthy stems reduced their yielding capacity by 28 per cent, of the mean cob weight of healthy stems (P <0·001).

In six experiments on early millet, little reduction in yield occurred, even when infestations were much higher than those normally experienced, but late millet suffered almost complete loss of yield in two experiments and more than 90 per cent, of the stems were bored in. two other experiments, in which yields were low. These results and general observations indicate that stem borers, particularly C. ignefusalis, play a major part in limiting yields of late millet.

In six experiments on guineacorn, significantly so in three of them, the yield per bored stem was higher than that per unbored stem, and it appears that borers concentrated on or were concentrated on the larger, higher-yielding stems, possibly as a result of selective oviposition. In one other experiment, stems bored by first-generation larvae yielded significantly less than unbored stems but neither in this nor in any other experiment was over-all borer attack related to a reduction in yield and it is generally true that excellent yields of guineacorn can be obtained in the presence of high populations of borers.

Reduction of the carry over of diapause larvae, by destroying or composting crop residues or removing them from the field, has given good control on the experimental farms at Samaru but it is difficult to extend these measures to local farms. Farmers should clean up their fields before the beginning of the rains and stems that are to be used for building should be exposed in the open during the dry season; to reduce populations of diapause larvae. Insecticidal control has as yet shown little promise and plant breeding for resistance has not begun.

The necessity for further work to confirm the general conclusions drawn here is stressed and possible lines of investigation are indicated.

The age compositions of samples of females of Glossina pallidipes Aust., G. palpalis fuscipes Newst. and G. brevipalpis Newst., are analysed by means of a method of age determination based upon the changes occurring in the reproductive system during successive gonotrophic cycles. This method of age determination is described in detail.

Females were sampled by three main methods: in traps, by catching on a bait-animal, and on a fly-round. Some flies were also found as resting flies in the undergrowth.

Trap-caught samples of G. pallidipes were older (i.e.), contained a larger proportion of old flies (and a smaller proportion of young flies) than the hand-caught samples. The bait-caught samples were intermediate in age structure. Correlated with the increasing mean age in the hand-caught—bait-caught—trap-caught series was an increase in the proportion of females carrying third-instar larvae and a decrease in the proportion of those carrying eggs. Results with samples of G. palpalis fuscipes and G. brevipalpis were not so well defined.

The results of dissecting teneral and non-teneral nullipars of G. pallidipes and G. palpalis fuscipes indicate that females of the latter are inseminated some time before they take their first blood-meal, but teneral females of G. pallidipes are inseminated when they come to the host to feed or after they have fed.

The relation of the ovarian method of age determination to Jackson's (1946) wing-fray categories in females of G. pallidipes, and the probable epidemiological importance of the samples, are also discussed.

Diparopsis watersi (Roths.) is the principal pest of cotton in the Abyan Delta, West Aden Protectorate, an almost rainless area where the crop is sown in August–September on floodland watered by seasonal streams rising on the Yemen plateau. From December onwards, a large proportion of the pupae formed exhibit a facultative diapause, and adults emerging from these are responsible for infesting the following season's crop, the size of the initial population in which depends upon the extent to which this moth flight is intercepted by cotton in a suitable stage for breeding. When initial populations are low, most of the crop is set before the population has greatly increased by short-cycle breeding, shedding of flower buds and young bolls following attack by D. watersi is slight in relation to natural shedding, and little crop loss is attributable to this boll-worm. When a large part of the moth flight is intercepted, initial populations are high, heavy shedding is caused, and varying degrees of loss ranging up to virtual crop failure can result.

Investigations show that, when land is watered, emergence from diapause pupae is almost completed within six weeks; it is thought that watering reduces soil temperature below the high level that appears to inhibit diapause development throughout the summer. The resulting moth flight is largely spent before flower buds become available and the initial population in the crop is low. When land that was under cotton the previous year is not watered, soil temperatures remain high, and this is thought to account for a delay in emergence until temperatures fall, giving rise to a moth flight extending from November to January. Much of this is intercepted by cotton in a condition suitable for breeding by D. watersi, the initial population is high and heavy losses can result. The annual variation in the volume of the floods results in corresponding fluctuations in cotton acreage, a varying proportion of the previous year's cotton land remaining unwatered. The histories of the four cotton crops 1958–59 to 1960–61 indicate the extent to which infestation of the crop depends on this factor. In a year of poor floods following a large acreage in the previous year, infestations tend to be severe, and, conversely, a large crop following a smaller one the year before is normally lightly attacked. Failure to observe a close season may also promote heavy infestation, since it results in the provision of a food supply for the offspring of the main emergence from diapause pupae, which otherwise would not survive.

Endrin has proved very effective in the control of D. watersi, and Sevin also shows promise, but several applications over the two months following the first flower buds are necessary and it is doubtful whether these could be economic. A close season is essential, and the effects of its violation have been seen in recent years. The available flood water should be used more economically, using a system of area rotation of crops whereby cotton would be followed by another crop and that in turn by a dry fallow. The spring floods, which normally run to waste, could thus be utilised, and this would reduce the incidence of unwatered cotton land.

The species of the genus Pyrilla Stål (Fulgoroidea: Lophopidae) found in India and Ceylon are reviewed on the basis of population samples from different localities. It is considered that two polytypic species are present: P. perpusilla (Wlk.), widespread in India and now recognised as extending to Ceylon and to Thailand, and P. aberrans (Kby.) (sensu stricto), formerly regarded as being confined to Ceylon, but now found to occur also in south India. Ten geographical subspecies of the former and five of the latter are described and named.

During recent work on the coconut leaf moth, Agonoxena pyrogramma Meyr., in New Britain, Mr. R. W. Paine has found that this insect, whose larvae live in the leaflets of the coconut palm, is parasitised by a very small Tachinid fly which belongs in the genus Actia R.-D.; this same Tachinid was briefly alluded to as an unidentified dipterous parasite of Agonoxena pyrogramma by O'Connor (1954). The Actia species concerned belongs in the group of species in which the fifth wing-vein (M3 + 4) is setulose, and seemed on first examination to be almost indistinguishable from A. darwini Mall., an Australian species common in Queensland. However, examination of the male genitalia has shown striking differences from A. darwini and it is evident that a new, closely allied, species is involved; this new species is described below. Following the description I have given a key to the Indo-Australasian species of Actia in which the fifth vein is setulose, so that A. painei sp.n. can be placed.

The toxicities of sprays of some insecticides used against locusts have been determined. The LD50's of γ BHC, diazinon, and dieldrin to both flying and settled adults of Schistocerca gregaria (Forsk.) were between 0·9 and 1·5 times those of the same formulations when applied as a single drop to the abdomen. The toxicity of these insecticides was not affected by the size of the spray droplets when these ranged from about 60 to 250 µ in diameter. The toxicity of DNC, however, was always less by spray application than when applied by micro-drop syringe and was affected by the droplet diameter (droplets of 100 µ being 1·5 times as toxic as those of 200–230 µ) and by whether the locusts were sprayed in flight or when tethered on a card (those in flight being about 1·6 times as susceptible to 100 µ droplets as those at rest). A tentative explanation of this effect is given.

The speed of action of the insecticides was compared and the effects of flight activity on susceptibility to the insecticides when sprayed over the flying insects was examined, but none could be detected by the technique used.

The dubas bug, Ommatissus binotatus lybicus de Berg, is a serious pest of the date palm (Phoenix dactylifera) in Iraq, where there are two generations a year. Both nymphs and adults, which are described, suck the sap from the date palm. Repeated heavy infestations cause the weakening and death of some of the palms.

The eggs are laid on all the green parts of the palm except the fruits, the majority on the leaflets, especially the upper surface. They are distributed evenly on the four aspects of the date palms, but unevenly on the frond rows, the second and fourth oldest rows having the majority of the eggs in the overwintering and summer generations, respectively. Deposition of eggs of the overwintering generation began in the second week of November and hatching started during the first week of April, the nymphal period lasting 47 days and the adults surviving for 15 days. Eggs of the summer generation were deposited from the second week of June, and hatching started in the first week of August, the nymphal period lasting 50 days and the adults surviving for 13 days. There are five nymphal instars.

The nymphs excreted droplets of honeydew, and both nymphs and adults prefer the shady parts of the date palm. In order to escape the severe heat of the summer days, the nymphs and adults of the overwintering generation migrated towards the bases of the new fronds. The sex ratio was nearly 1:1, and the mean number of eggs laid per female was 106. The mortality rate for a constant population level was 98·11 per cent.

The eggs were parasitised by a small Chalcidoid. The larvae of the lace wing Chrysopa carnea Steph. and the adults of Coccinella septempunctata L., C. undecimpunctata L., and Chilocorus bipustulatus (L.) preyed upon the nymphs and adults.

In tests with inseeticidal sprays containing 240 g. active ingredient per 100 gal. applied at the rate of 1½ gal. per palm against adults and nymphs, DDT and malathion were equally effective, but Dipterex was less so. Similar concentrations of mixtures of malathion with heptachlor and DDT with diazinon were also effective.

Solutions of dieldrin, γ BHC, p, p′DDT and Baytex were applied topically to pregnant females of Glossina morsitans Westw. and also, in most cases, to fertilised flies over 21 days old and not noticeably pregnant, to virgin flies over 21 days old, and to males over 18 days old. Pregnant flies required about nine times as much dieldrin as young flies for comparable mortalities, and non-pregnant fertilised flies about four times as much. It was not possible to determine proper regression lines for other insecticides and classes of flies but significant increases in tolerance, as compared with that of young flies, were shown by pregnant flies to γ BHC and DDT, by old virgins to dieldrin and DDT but not γ BHC, and by fertilised flies to γ BHC and DDT. Pregnant flies and virgins showed no increased tolerance to Baytex, and old males showed none to dieldrin, γ BHC or DDT.

These results are discussed in relation to aerial spraying of tsetse habitats and it is suggested that they explain some unexpected past results.