Anopheles aconitus Dön. has long been known as an important vector of malaria in Indonesia. More recently it has been shown to be the principal, if not the only vector in the inland areas of Java. A. maculatus Theo. has been regarded as an important vector in hilly regions.

The observations recorded in the present paper were carried out in an inland area in East Java between June 1957 and May 1958, and in a hilly one in West Java between April 1956 and March 1957, and were concerned, in particular, with the resting and feeding habits of these two species in so far as they might influence methods of control.

A. aconitus is found in great numbers throughout the year with a major peak of density from March to May, about harvest time of the first and more extensive rice crop.

In the areas studied, A. aconitus is largely exophilic and, where man is concerned, exophagous, nearly three times as many examples being taken biting man outdoors as indoors, and 17 per cent. of 359 examples taken outdoors were positive for human blood as compared with 5 per cent. of 1,438 examples from all situations. Of the remainder, 93·5 per cent. were positive for ox. On the whole, therefore, this species is highly, though not exclusively, zoophilic and readily enters cattle-sheds, built of bamboo matting, to feed, and, in those sheds that have walls as well as roofs, up to 75 per cent. may remain for at least two hours after having fed, and appreciable but variable numbers of fully fed individuals may remain during day-time.

Most of the feeding on man outdoors took place before midnight, and, on cattle in sheds, between midnight and 0600 hr., with peaks between midnight and 0100 hr. and between 0400 and 0500 hr., respectively. Peak periods of entry into an animal-baited trap were during the second and fourth quarters of the night.

These results differ somewhat from those reported from certain other localities in Java by other workers. There is, therefore, a need for careful repetition, in other areas, of studies of the bionomics and for experiments on the effect on a population of A. aconitus of applications of a residual insecticide.

A. maculatus occurs in the hilly area in considerable numbers throughout the year, and there seems to be no great seasonal fluctuation. This species rests mainly on coffee and palm plants both by day and by night, but readily enters cattle-sheds at night. No blood-meals from this species were subjected to the precipitin test. It is suggested that the importance of A. maculatus in the transmission of malaria needs further investigation.

Over 1,000 examples of A. maculatus and A. aconitus, taken in the hilly area, were dissected, but no malaria infection was found.

A. vagus Dön. is present in the inland area in large numbers during the greater part of the year, with its peak from November to February, during the rainy season. It is more endophilic and endophagous than A. aconitus but is not considered important in malaria transmission.

A. annularis Wulp has its peak in March, and A. kochi Dön. in May. A. barbirostris Wulp, A. subpictus malayensis Hack, and A. tessallatus Theo. were found only in small numbers. All these species are highly zoophilic in the areas studied; they are not considered important in malaria transmission.

Investigation of the gall midges of crops in Nigeria has revealed an undescribed: species which causes sorghum stems to lodge and two species, one on rice, the other on benniseed (Sesamum orientale), which are known as pests of these crops in India.

The material on which this paper is based was bred from Nacoleia octasema (Meyr.) in New Guinea. The species of the new genus, herein described, was found to be an important primary parasite of the larva. The Tyndarichus species is a hyperparasite.

The new genus is close to Copidosoma and Litomastix, and very closely resembles the other genera of this group in both structure and habits. In the species described below the male is not unlike the males of some species of Copidosoma, and the female resembles Litomastix; the species appears to be polyembryonic. In the present state of the systematics of the ENcyrtidae it is deemed advisable to describe this species under a new genus.

I am grateful to Dr. J. Ghesquière, who consented to examine material of this genus and was generous in his advice and assistance.

Under certain conditions, Callosobruchus maculatus (F.) produces males and females which are distinct from the normal ones. These are called here the “ active ” form, and in southern Nigeria they occur most commonly during the months March to June. The active form has a longer pre-adult stage than has the normal form and it flies readily, unlike the normal form. There is some evidence which indicates that a genetic factor is involved in the production of the active form but no clear indication as to what external factors are involved. The normal female has mature eggs in its calyces within a day of emergence, and will lay about 60 eggs. The active female was found to have immature ovaries on emergence and these did not develop to any great extent in the conditions employed. About three-quarters of the active females never produce any eggs, and the rest produce an average of seven. This difference in egg-production probably makes food reserves available which are used to prolong the life of the active female. The eggs laid by active females are rarely fertile, and when adults do emerge they are apparently normal males and females.

The type form of Aëdes (Stegomyia) aegypti (L.) is widespread in southwestern Nigeria, breeding in the basins of rotting tree stumps in the coastal mangrove swamp, in holes in living trees in the freshwater swamp zone and near Lagos and in domestic containers restricted to village clearings in the inland forest zone. Pot surveys were carried out in a rain forest village 50 miles north-west of Lagos and in the capital itself. Baked clay pots holding half a gallon of water were used in each case and were placed in three situations, inside houses, outside but in otherwise sheltered positions, and in fully exposed positions. The degree of larval infestation in both cases was greatest inside houses, but the behaviour pattern was less domestic in Lagos. Larvae were found in pots contaminated with decaying vegetable matter in Lagos but not in the village. Spraying tests indicated that houses and foliage afforded varying degrees of protection to the immature stages of the mosquito. Control of this species is made difficult by the localisation of the immature stages in relatively inaccessible sites and it is suggested that individual treatment of larval habitats by insecticidal pellets before the commencement of the rainy season would ensure a high mortality of first-generation larvae. The toxicity hazard to man is not considered to be great. The development of resistant and wild populations is discussed.

Since the sharply defined biting cycle shown by outdoor populations, in Uganda, of Aëdes aegypti (L.), which closely resembles oviposition and general activity rhythms, could not be reconciled with the ill-defined patterns found in domestic populations, on the Kenya coast, in the absence of knowledge of the composition of the population involved there, 24-hour baited catches were made at Ganda on the Kenya coast, and the abdominal colour pattern of each individual was noted. In the series there was gradation from the darkest to the palest.

Of 427 females taken biting, 82·1 per cent, were of var. queenslandensis (Theo.) in the generally accepted sense, 14·5 per cent, of the type form and 0·9 per cent, of subsp. formosus (Wlk.). The material of var. queenslandensis was further divided into two groups in which the lateral spots on the abdominal tergites were of silver and matt white scales, respectively.

Very similar biting cycles, with the main peak in the hour before sunset, occurred both inside a hut and within an adjacent compound, although catches were not concurrent and were made under different seasonal conditions.

The distribution of the various colour forms in the total catch was independent of the hour of capture.

There is a resemblance between these cycles and those reported in comparable situations in Nigeria, where, with the exception of the paler forms, the population of A. aegypti is similar to that at Ganda. It is concluded that the main biting peak is shortly before sunset. Subsidiary peaks, when present, occur with increasing intensity as the day progresses.

The relationship of biting activity to other aspects of general activity is discussed, and it is concluded that several aspects require further investigation.

The following hypothesis is offered to account for the various patterns of biting cycle observed in different situations. It is suggested that A. aegypti possesses an endogenous multi-peaked diel rhythm of activity. Activity impulses occur in a cycle of waves of increasing intensity from dawn onwards, reaching a maximum at the end of the daylight period, and a biting peak will result when such an impulse coincides with environmental conditions within the range between upper and lower thresholds of activity.

A study has been made of the rate of oviposition, on parboiled milled rice, of the small strain of the rice weevil, Calandra oryzae (L.), under normal laboratory conditions of temperature and relative humidity (means 27°C., 80% R.H.) in Sierra Leone, and of the utilisation of grains for oviposition.

On the average, a female laid 68 eggs in all, over an oviposition period of 71 days, the peak of egg-laying being reached during the third week. Only 13 per cent, of grains were utilised. Differences between the results obtained and those recorded by previous workers are discussed.

The mean length of life of male and female weevils was found to be 113 and 97 days, respectively.

Several collections of pupae and adults of Simuliid Diptera were made in British Honduras between 9th January and 18th February 1958. Samples were collected in the Mountain Pine Ridge and El Cayo areas in the west, and along the highway traversing the eastern part of the country between Caves Branch and Stann Creek.

Thirteen species of Simulium were found, nine of which are named, including S. quadrivittatum Lw. and S. metallicum Bellardi which are very annoying biters. A, few observations on distribution and habits are recorded.

Of the two anthropophilic species of Simulium found, one is known to be a vector of onchocerciasis, if only of secondary importance, and the capability of the other to transmit the disease is unknown. The disease has apparently never been established in British Honduras and is present in Guatemala. The risk of infection to settlers moving into territory near Guatemala cannot be assessed without detailed knowledge of the epidemiology of the disease in Central America.

Walnuts grown and shelled in the Dordogne and adjacent regions of France are exported to Britain and other countries. The inspection of cargoes arriving at Liverpool between July 1955 and July 1958 has shown that they may frequently be infested by a number of species of insect pests. Of the 20 species recorded, six occurred regularly. These were Oryzaephilus surinamensis (L.), Aphomia gularis (Zell.), Plodia interpunctella (Hb.), Cryptophagus subfumatus Kraatz, Nemapogon granella (L.) and Enarmonia sp. During that period, changes occurred in the levels of infestation on parcels and the relative abundance of the species. In particular, there was a considerable increase in the occurrence of O. surinamensis. Though the general levels of infestation were light, parts of 58 per cent, of the cargoes had to be fumigated to prevent pests being distributed to factories, bakeries and shops in Britain and on transhipped parcels to Canada, U.S.A. and the Eepublic of Ireland. Though many of the species found are already established in those countries where conditions are suitable for their development some are still limited in their distribution. These include A. gularis, a serious pest of nuts, dried fruit and cereals. If the further spread of this and the other pests is to be prevented there is need for a more general application of control measures in the country of origin with strict control and possibly fumigation of cargoes before shipment.

The Pentatomid bug, Scotinophara lurida (Burm.), is a serious pest of the rice crop in certain areas of Ceylon. Five or six generations develop on the two annual rice crops, and that which attains the adult stage at the time of harvest of either crop ‘aestivates’ and does not become sexually mature until later. The generations that become adult earlier in each crop season become sexually mature forthwith, and mate and oviposit.

In 1952, laboratory experiments to ascertain the susceptibility of adults of S. lurida to a range of modern organic insecticides, and field experiments on insecticidal control, were initiated. The insecticides tested were DDT, BHC, endrin, dieldrin, malathion, Chlorthion, Guthion, Dipterex, diazinon and parathion.

In the laboratory, freshly emerged, sexually mature and aestivating bugs were tested separately by topical application on the abdomen, and it was found that the insecticides could be arranged in the following descending order of toxicity, based on the LD50, against the sexually mature adult:— γ BHC, endrin, dieldrin, parathion, Dipterex, Chlorthion, diazinon, Guthion, malathion, DDT. The adults of the aestivating generations, at least prior to becoming sexually mature, were markedly more resistant to all the insecticides tested than were sexually mature bugs of uninterrupted development, the resistance ranging from two-fold to nineteen-fold that of the latter.

There is some indication that tolerance to every insecticide does not necessarily increase with increasing age and sexual maturity of the normal adult bug. Thus, whereas with the organophosphorus insecticides increasing sexual maturity is associated with an increase in tolerance, with DDT and endrin the bugs appear to become more susceptible with increasing sexual maturity, while with γ BHC and dieldrin there is little change.

The chlorinated hydrocarbon insecticides DDT, toxaphene, chlordane, aldrin, dieldrin, endrin, isodrin and γ BHC and the organophosphorus insecticides malathion, diazinon, Dipterex, Chlorthion, Guthion and parathion have been tested as emulsion sprays against S. lurida in the field. DDT and toxaphene gave the poorest results with about 85 per cent, control of the pest in 24 hours when applied at and above a concentration of 0·045 per cent, active ingredient. The other insecticides are arranged thus in descending order of efficacy against the pest considering the minimum dosage required to give 100 per cent, or near 100 per cent, control within 24 hours of application of the treatment: —parathion 0·02 per cent.→ endrin 0·03 per cent. = Chlorthion 0·03 per cent.→ Dipterex 0·03–0·04 per cent.=Guthion 0·02 per cent.→ dieldrin 0·06 per cent.= malathion 0·06 per cent.= γ BHC 0·06 per cent. → diazinon 0·07 per cent. Aldrin and isodrin were of about equal effectiveness giving about 90 per cent, control of the pest within 24 hours when applied at a concentration of 0·06 per cent, active ingredient.

Of the dusts tested, both γ BHC at 1·3 per cent, and dieldrin at 2·5 per cent, gave 100 per cent, control of the pest in 24 hours when applied under still and dewy conditions obtaining in the morning. Under dry, windy conditions however, γ BHC at 1·3 per cent, and 3 per cent, gave better control of the pest than did dieldrin or aldrin dusts.

Parathion, dieldrin, endrin, Metasystox and Ekatin were tested for residual action against S. lurida on the rice crop. Parathion was the most effective residually for a period of two days with dieldrin coming next in order of residual effectiveness.

Metasystox and Ekatin were tested for their systemic action against S. lurida on three-week-old and ten-week-old rice plants as foliar sprays and as root treatments. Systemic action of a low order of effectiveness against the pest was demonstrated in all cases but the poor results achieved and the high rates of application involved did not warrant their consideration for practical field use.

In Trinidad, the only serious pod borer attacking pigeon peas is Ancylostomia stercorea (Zell.). This species breeds throughout the year. The eggs are laid on the young pods and the larvae feed on the developing seeds and later pupate in the soil. The complete life-cycle requires 26–32 days.

Eight species of parasites were reared from the larvae of Ancylostomia. Life-history studies and rearing techniques for the six commonest species are presented.

Apantelcs etiellae isolatus Mues. is a solitary endoparasite attacking first- to third-stage host larvae. It emerges from the fourth-stage host and constructs a white cocoon in the pod. The life-cycle takes 14–18 days.

Phanerotoma bennetti Mues. is a solitary egg-larval parasite. The egg is laid in that of the host, but the parasite does not complete development until the host has reached the final larval stage and constructed a cocoon. A generation is completed in 20 to 28 days. A method of breeding this species on Ephestia cautella (Wlk.) is described.

Eiphosoma annulatum Cress, is a solitary endoparasite attacking first- to fourth-stage hosts. The parasites emerge from fifth-stage hosts which may be stunted in size but construct normal cocoons. The life-cycle is completed in 26–35 days.

Bracon thurberiphagae (Mues.) and Bracon cajani Mues. are gregarious ectoparasites of similar habit. They paralyse second- to fifth-stage larvae and deposit eggs on or near them. The life-cycle is completed in 13 to 16 days. A method of rearing field-collected immature stages is described.

Perisierola sp. is a gregarious ectoparasite. The adult enters the pod, paralyses a host, and attaches her eggs directly on to the caterpillar. Second- to fifth-stage hosts may be attacked but the larger hosts are preferred. The female frequently remains with her progeny until they have completed their development, which requires 11 to 15-days.

Hyperparasites attacking the parasite pupae are listed.

Details of a shipping container and methods of rearing and shipping parasites to Mauritius for trial against Etiella zinckenella (Treitschke) and Maruca testulalis (Geyer) are described. From a stock of more than 44,000 cocoons so sent two species, Bracon cajani and Eiphosoma annulatum, have been successfully established in Mauritius.

The biting behaviour of East African species of Aëdes in the subgenera Aëdimorphus, Banksinella and Dunnius, as shown in numerous series of 24-hr, catches made predominantly in Uganda, is discussed. It is shown that with the single exception of A. (A.) natronius Edw., which is arboreal, all the species encountered have been most prevalent at ground level. They bite mostly by day, but A. cumminsi (Theo.) shows a marked peak of activity from just before to just after sunset, and A. natronius is crepuscular. When, however, samples were obtained in environments less favoured than the forest floor, and in which the mosquito concerned was less abundant, the biting cycle might be altered. Thus various species which were essentially diurnal at ground level in forest might be nocturnal in the canopy or in banana plantations.

In some cases there seemed to be a tendency towards a group pattern of behaviour. For example, in the abnormalis (Theo.) and tarsalis (Newst.) groups of Edwards it was found that at least three species showed very similar biting cycles. A fourth species, A. nigricephalus (Theo.), which occurs in Nigeria, is reported there to differ in its biting habits, and is also strikingly different in appearance and in the structure of the terminalia.

Members of all three subgenera have been involved in various isolations of virus, but it is not possible to prove that they, rather than other species of Aëdes included in the infected lots, were the vector mosquitos, except in the case of the A. tarsalis group, from which there have been two definite isolations of Rift Valley fever virus, and in that of A. circumluteolus (Theo.), which has been shown by recent work in South and East Africa to be of major importance, well over 20 isolations of virus having been made from this species. So far as is known at present, seven separate viruses and one distinct variant have been isolated from A. circumluteolus, and other members of the subgenus Banksinella also appear to be involved in transmission.

The bean fly, Melanagromyza. phaseoli (Coq.), the larvae of which tunnel in the stems of Phaseolus vulgaris, is a pest of this crop in Tanganyika. Field trials there in 1956 on haricot-type beans showed that dressing the seed with chlorinated-hydrocarbon insecticides could prevent attack for at least 30 days after germination; organophosphorus insecticides were less effective. In four further field trials (A-D), in 1957, the insecticides and types of formulation used were aldrin (wettable powder and emusifiable concentrate (EC)), endrin (EC), γ BHC (dry dressing and EC), dieldrin (dry dressing and EC) and a proprietary organophosphorus systemic (dry dressing). Wet dressings were applied by treating the seeds with the liquid and drying immediately, and in one treatment aldrin as a wettable powder was applied dry and the seeds then damped and dried at once.

Damage was assessed on an arbitrary scale on trials A and B, and yields measured on trials A, C and D. Results varied between insecticides and under different growing conditions, but wet dressing with endrin at 213 mg. per 100 g. seed, of which about 50 per cent, was retained on the seeds, resulted in the lowest damage, amounting to 7·7 compared with 52·6 for the control (no dressing), and the highest yield, amounting to 13·5 units compared with 8·6 for the control. All treatments, except that with the organophosphorus dust, reduced the damage significantly below that in the control. Wet dressings were usually more effective than dry dressings with the same insecticide, as regards both yield and reduction in damage. This may be associated with the better retention of wet dressings, which was shown by the results of chemical analysis of the residues on the seeds left in the drill hopper after sowing.

Seed treatments of calomel, DDT, dieldrin and aldrin were compared in three seasons′ field trials for use against onion fly, Delia antiqua (Mg.). Excellent control and also improved germination were obtained with 0·5 oz. actual dieldrin per lb. of seed applied with a sticker, with or without thiram. Similar results were obtained with 0·1 and 1·5 oz. actual dieldrin per Ib. of seed, but 3·2 oz. reduced germination. Aldrin at the same rates gave excellent control but reduced germination. DDT at 1·5 oz. and 3·2 oz. gave good control early in the season, but was not sufficiently persistent and seriously reduced germination. Calomel gave little control, although it improved germination.

Although kerosene used as a sticker for a dust was satisfactory, it was liable to reduce germination seriously when used alone, except at very low rates.

Seed treated with DDT, dieldrin or aldrin may be stored safely for a month or two in unsealed containers but not in sealed containers.

There was close correlation between the percentage of plants attacked and the yield per 100 plants in the original stand. For every 10 per cent. of plants killed by onion fly there was a 10 per cent. loss of the potential yield.

Even where the onion-fly attack was heavy, comparatively few plants showed symptoms of damage at any one time, which suggests that the level of attack is frequently under-estimated.

The life-history and seasonal cycle of the Lepidopterous borer, Busseola fusca (Fuller), the most serious pest of maize in Southern Rhodesia, have been studied there.

There are two generations in the year, the majority of the full-grown larvae of the second entering diapause, in which condition the dry season is passed in the maize stem, but a proportion of the second-generation consists of short-cycle individuals that give rise to moths irregularly during the dry season.

In the field, the egg stage lasts about 7–11 days, according to the time of year. In the laboratory, there are six, very occasionally seven, larval instars in the first generation, occupying about 37 days, and the pupal stage lasts about 17 days. In the second (diapausing) generation there may be one or two additional moults without appreciable change in size, and there is considerable variation in the length of instars and in the date of entry into diapause, but by mid-June the bulk of the larvae that will survive are in diapause. The majority of diapause larvae pupate in early November, the pupal stage lasting about 23 days.

The feeding habits of the larvae are described and reference is made to other food-plants.

The length of life of the adult, in cage conditions, averages 6–7 days, but there is great variation. When provided with diluted honey, adults were not observed to feed, and absence of such food did not appear to impair egg-laying. The sex ratio was 1:1, but in catches at a light-trap the ratio of males to females was 5:1. Copulation takes place shortly after emergence, and oviposition may begin within 24 hours of emergence.

The average number of eggs laid per female in cages was 360 over an average of four days, one female laying 1,032. Several batches of eggs may be laid in one night. A single mating appears to be sufficient, but males may copulate with more than one female. Eggs laid by virgin females do not hatch.

Diapause is thought to be induced by larval feeding on drying food. Continuous rearing of non-diapause generations can be achieved by feeding the larvae on fresh, green maize. Similarly, in the field, irrigated out-of-season maize will support non-diapause generations and constitute a source of infestation that may render ineffectual the normal routine destruction of all plants of the previous dry-land farming season.

The main parasite is the Tachinid, Sturmiopsis parasitica (Curr.), which may destroy more than 33 per cent, of the larvae in either generation.

In experiments with Aëdes aegypti (L.), fourth-stage larvae bred at 30°C. survived exposure to 0·5°C. for 7 hours, but none recovered after exposure for 17 hours, although nearly all those from the same culture that had been acclimatized for one hour to 18 or 20°C. did so. No such effect followed acclimatization at 10°C., at which larvae are in chill coma. Larvae acclimatized at 18°C. survived exposure to 5°C. for longer than did those from 30°C. Earlier work showed that the thermal death point, for a one-hour exposure, was 42°C. for larvae acclimatized at 30°C. but rose to 44°C. for larvae acclimatized to 37°C. It is concluded that the effects of high or low extremes of temperature may be substantially modified by a brief period of acclimatization at a less extreme temperature.