Previous records and new data on infection rates in species of Glossina inhabiting southern Nigeria and the Southern Cameroons are presented, and the probable economic importance of each species is assessed.

The trypanosome infection rates were highest in those species of tsetse which fed largely on Bovidae.

The rarity of human trypanosomiasis in southern Nigeria and the Southern Cameroons is attributed largely to impersonal man/fly contact; under such conditions a low proportion of infected flies is to be expected. G. palpalis (R.-D.) is not an important vector of sleeping sickness, as it is in northern Nigeria. The incidence of infection in G. palpalis was generally very low; cases of bovine trypanosomiasis do occur in areas where G. palpalis is the only tsetse species present, but it is not considered to be an important vector.

Little information is available on G. tachinoides Westw. and G. caliginea Aust. in southern Nigeria; both have probably been at least partly responsible for some of the rare outbreaks of sleeping sickness reported from the south. G. tachinoides may be of some significance as a vector of animal trypanosomiasis.

The infection rate in G. longipalpis Wied. at the West African Institute for Trypanosomiasis Research Field Station at Ugbobigha was 21·5 per cent.; this species is believed to be of major economic importance because its presence must prevent the keeping of cattle in large areas of potential grazing.

At least 13 per cent, of examples of G. medicorum Aust., G. fusca (Wlk.) and G. nigrofusca Newst. were infected in the populations examined, and the first two species are considered to be of economic importance because they penetrate potential grazing areas.

G. pallicera Big., G. tabaniformis Westw. and G. haningtoni Newst. are confined to rain-forest and were found to be lightly infected; they are therefore not considered to be of economic importance, except possibly as a source of infection to cattle on trade routes.

No data are available for G. nashi Potts.

In plot trials with seed dressings on late-sown oats against shoot attack by frit fly, Oscinella frit (L.), chiefly near Cambridge, England, γ BHC, parathion, dieldrin, heptachlor, Rogor and WL 1650 (Telodrin) (1,3,4,5,6,7,8,8-octachloro-3a,4,7,7a-tetrahydro-4,7-niethanophthalan) (dry and wet) reduced the attack but the effect was variable and for the most part not appreciable.

In 1952 and from 1956 to 1960, trials were made on the effect of late sprays of various insecticides applied to late-sown oats when symptoms of frit-fly attack were already conspicuous and sometimes severe. An advantage of this type of treatment over preventive sprays is that it ensures that the treatment is applied only where and when necessary. Single sprays of parathion, dieldrin, γ BHC and Rogor prevented or markedly reduced further attack and they were most effective when applied within about 15 days of the beginning of egg-laying and when plants were in the young seedling stage. Compared with the best treatment of two early preventive sprays of DDT there was only a slight reduction in yield. Parathion and to lesser extent γ BHC killed many larvae inside the shoots and probably prevented others from entering the shoots.

Coconut poonac, the cake left over after the extraction of oil from coconut pulp, has been used very successfully for breeding Musca d. vicina Macq. in the laboratory in Ceylon. The fly lays its eggs in the poonac and the larvae live and pupate in the same medium.

A study has been made of the length of life, fecundity, oviposition and the effects upon them of adult nutrition in the varied carpet beetle, Anthrenus verbasci (L.).

The length of the inactive (unmated) life for males and females at 20°C. and 70 per cent. R.H. was 7·5 and 7·7 days, respectively. This period, which is spent in the moulted last larval skin, decreased with rise in temperature, from a mean of 32·4 days at 10°C. to 3·8 days at 25°C. Humidity differences had relatively little effect.

The effects of various diets on the length of life, oviposition cycle and fecundity of active adults were observed. The experimental diets were water, water with pollen, water with albumen, sugar solution, sugar solution with pollen, sugar solution with albumen, and the control group in which the beetles were deprived of food and water. The sugar solution was a mixture of equal parts of glucose, sucrose and fructose in water.

There were no differences in length of life between male and female beetles (males 18·2–20·9 days, females 22·1–26·1 days) given water, water with pollen, water with albumen and those deprived of food and water. But there was an increase for both sexes when the beetles were given sugar solution, and a further increase, to a mean of 58·3 days for males and 69·5 for females at 20°C. and 70–90 per cent. R.H., when albumen was added to the sugar solution. However, although sugar solution with pollen increases still further the length of life of the males, that of the females was no different from what it was on sugar solution alone.

The preoviposition period ranged from 3–14 days with a mode about the fourth day.

The oviposition cycle consisted of three clearly denned peaks of oviposition on about the 6th, 12th and 17th days. There was a similar pattern in all the groups except that those given sugar solution continued to lay, at a low rate, after the end of the third peak.

The fecundity of beetles deprived of food and water was 50·3 eggs; for beetles given water, water with albumen and water with pollen there was a significant decrease; for beetles given sugar solution there was an increase which became significant when pollen or albumen were given in addition to the sugar. Maximum fecundity occurred on a diet of sugar solution with albumen.

There was significant correlation between length of life and weight on emergence for males given water, water with pollen, or water with albumen, and for females given water with pollen or water with albumen. There was significant correlation between fecundity and emergence weight for females deprived of food and water, given water alone and water with pollen.

Pygostolus falcatus (Nees), an endoparasitic Braconid of the subfamily Blacinae, was reared from Sitona lineatus (L.), S. hispidulus (F.) and S. humeralis Steph. of Swedish origin. The life-history and immature stages of P. falcatus were studied in the laboratory at 74°F. and in field cages preparatory to its liberation in Canada as a control agent of the sweetclover weevil, S. cylindricollis Fhs.

The immature stages develop in the haemocoele of the weevil. After deposition, the egg increases in volume to a maximum of 335 times. At eclosion, the cells of the trophamnion dissociate and increase in volume in relation to the growth of the larva. Supernumerary larvae are eliminated soon after eclosion, and one larva only develops in a host weevil. At 74°F., the final-instar larva emerges from the host weevil 15–16 days after deposition of the egg. Development of many first-instar larvae in a wide range of Sitona species was arrested by diapause. Five larval instars are described and illustrated. Oviposition is prevented in weevils in the summer of their development and eliminated in overwintered weevils by the parasite egg and first-instar larva. The weevil dies within hours of emergence of the parasite larva.

Reproduction is parthenogenetic and thely tokous. The maximum number of eggs laid by a female was 46; the number of eggs laid per day per female varied from 0 to 11. Oviposition takes place both in light and in complete darkness and a preference among species of Sitona was not evident. The maximum number of weevils parasitised by a female in a field cage was 39; the number parasitised per day varied from 0 to 8.

The species overwinters as a first-instar larva in weevils which became adult in the previous summer. There were two discrete parasite generations in 1958 in Swedish weevils, both of which developed in early and mid-summer within overwintered weevils. The maximum rate of parasitism of S. lineatus by larvae of the mid-summer parasite generation in 1958 was 73·3 per cent.

The value of P. falcatus as a control agent of Sitona populations is limited by low parasitism of the new weevil generation of the current year and diapause of the first-instar larva.

The larvae of the Lymexylid beetle, Melittomma insulare Fairm., bore into the bases of coconut palms. Associated with them are micro-organisms which cause extensive rotting of the bole, particularly at ground-level, and this results in the palm falling.

During 1953–58, an attempt was made in Praslin Island, Seychelles, to obtain maximum control of this pest using paradichlorobenzene as a fumigant. At the time of this treatment, 77 per cent, of the 90,500 coconut palms in the island were infested. Of these, about five per cent, were felled as worthless mountainside palms and nine per cent, fell during or within a week of treatment.

In 1960 it was found that a further 15 per cent, of the palms had fallen and of those still standing 53 per cent, remained infested. The continuing high loss of palms after treatment was due to the closed, moist fumigation chambers within the trunks encouraging the spread of rot, coupled with an incomplete kill of larvae.

A new method of treatment is described in which the necrotic wood is excised and a formulation of coal tar creosote and coal tar liberally applied. Praslin Island was retreated, using this tar method, and a plan to treat all the coconut palms in Mahé, the main island of the group, was subsequently commenced. Losses of palms during and within a week of treatment have been reduced to less than one per cent., and results are quoted which show that a single treatment can reduce a serious infestation in which 80 per cent, of palms are more or less heavily attacked to one in which only 18 per cent, of the palms are attacked and, on average, contain only five larvae. The treatment ensures that the entrances to the tunnels of these are exposed to view, and accordingly the surviving larvae can easily be killed.

The difficulty of deciding the systematic status of variations within and between populations of Tyrophagus is considered in relation to the wide distribution of the genus and the many materials it infests.

Variation within populations of what was thought to be one species infesting cheese is explained by the isolation of three closely similar forms which it is difficult, if not impossible, to separate by measurement alone. Frequency distributions overlap slightly for four linear measurement ratios on which separation is attempted, but differences between them are emphasised by differences in minute structural characters and they are therefore accepted as distinct species, identified as longior (Gervais, 1844), palmarum Oudemans, 1924, and putrescentiae (Schrank, 1781).

Variation between populations attacking plant materials and other stored products in addition to cheese is accounted for to some extent by the recognition of three further Tyrophagus species, oudemansi Robertson, 1959, brevicrinatus Robertson, 1959, and tropicus Robertson, 1959.

Within the species recognised, significant differences are recorded in dorsal hair characters and body proportions between populations on cheese produced in different geographical areas, and also between cheese populations and those infesting other materials, and these differences are thought to be at a racial level.

T. longior, T. palmarum and T. putrescentiae are found to be distributed around the world, but as cheese pests they occupy somewhat different, although overlapping, geographical zones, since longior is a temperate-to-cool form, palmarum a temperate form and putrescentiae a subtropical or tropical form. The three are also found to occupy different, but overlapping ecological zones, making possible their association in mixed populations.

Confusion in ecological data previously published on Tyrophagus is thought to be attributable in part to similarities in the morphology, geographical distribution and ecology of its species, and to their close association.

Solutions of six chlorinated-hydrocarbon insecticides in kerosene have been applied in drops of about 0·02 microlitre (µl.) to adults of Glossina morsitans Westw., 2–5 days old, one day after the first meal. This species is found to be unusually susceptible to this group of insecticides. In order of increasing toxicity they are: DDT and aldrin, γ BHC, dieldrin and endrin, Telodrin (1,3,4,5,6,7,8,8-octachloro-3a,4,7,7a-tetrahydro-4,7-methanophthalan). The LD50 of DDT was 0·0165 µg. (males) and 0·025 µg. (females), that of Telodrin was 0·00062 µg. (males). Susceptibility of the two sexes to DDT, γ BHC and dieldrin did not differ significantly. Two batches of flies tested with an interval of eight months differed by about two times in their response to dieldrin and γ BHC; but the response to DDT was unchanged. This difference was not seasonal.

For practical use, dieldrin is the best and cheapest available insecticide, a fact confirmed in the field. Only Telodrin might replace it.

Seven strains of Aëdes aegypti (L.), three DDT-resistant (from Trinidad (2) and Haiti) and four susceptible (from West Africa (2), Arabia and U.S.A.) have been investigated with respect to their attraction to oviposition sites illuminated at different levels. The resistant strains have tended to choose the darker sites (at 0·02 lumen per sq. ft. and below) and susceptible strains those illuminated at between 3·5 and 6·5 lumens per sq. ft.

Genetical crosses between a ‘dark-laying’ (resistant) strain and a ‘light-laying’ (susceptible) strain indicated that ‘light laying’ was fully dominant over ‘dark laying’ and it is suggested that the mechanism involved is probably simple. No linkage with the gene for physiological resistance to DDT could be demonstrated.

The expressivity of this character varied in certain circumstances with a tendency among most strains to lay at darker sites after the second and subsequent blood-meals. In spite of these variations, behaviour at any one time remained reasonably predictable.

The reflectance of the oviposition site did not appear to be important in determining the difference in behaviour between ‘dark-laying’ and ‘light-laying’ strains. On the contrary, it seemed probable that ‘dark-laying’ strains were attracted more to the dark situation in which the dimly-lit site was found rather than to the site itself. There was some evidence of exploratory activity in the initial stages of oviposition by a ‘dark-laying’ strain.

Resting habits proved very similar in two strains differing markedly in oviposition habit. For both strains, 0·1 lumen per sq. ft. was apparently too low to be attractive and 12 lumens per sq. ft. too high. Besting behaviour did not appear to be under such critical control by light as was oviposition.

Possible explanations for the differences in ‘oviposition light preference’ are discussed.

The situation following different degrees of discriminative clearing against G. morsitans Westw. was examined in eastern Ankole District, Uganda. In one area, where the treatment had been more intensive, the fly density was low, and it seemed that the population might be maintained by immigration from an adjacent area to the west, where treatment had been less intensive and in parts of which fly density was relatively high. The application of more intensive discriminative clearing of the fly's concentration sites to the western area, together with completion of the treatment of the eastern, failed to result in any marked effect on the tsetse population except as regards its distribution. Before this intensive clearing, concentrations of G. morsitans occurred in a double-storey vegetation type, the chief component of the upper storey of which consisted of Acacia gerrardii. After the upper-storey trees in this were felled, concentrations were found in groups of tall Acacia hockii, 12–18 ft. high, which had appeared to be of little importance to the fly before clearing. A year after the treatment of the western area there was no apparent reduction in fly density. The feeding habits and rate of utilisation of reserves of the flies showed no significant change as a result of clearing.

It seems that the failure of the discriminative clearing régime applied in this area, compared with the effect produced by less intensive clearing elsewhere in Ankole, is due to the presence in this area alone of the groups of tall A. hockii.

The larvae of the Melolonthid beetle, Lachnosterna. consanguinea (Blanch.), have been found to be very destructive to sugarcane in the Dalmianagar area in Bihar, India, since 1956 when they were first recorded there. The pest has since been found to occur in serious numbers in certain adjoining areas and also in Bihta in Patna district. Damage is done by the larvae by feeding on cane roots. Heavily infested cane clumps dry out completely and in severe infestations as much as 80 per cent, of the crop is lost. The infestation occurs only on light sandy soils; crops on clay soils are not affected. The February-planted crop suffers more seriously than that planted in October. The adults have not so far been observed doing any damage to sugarcane.

The emergence of adults starts in the last week of April, but a rush of emergence occurs only after the first shower of rain. The adults are nocturnal in habit and feed on leaves of certain bushes and trees during the night. They hide themselves in loose moist soil in day-time. Mating takes place after dusk during the flight season, and eggs are laid in the soil at a depth of 5 to 10 cm. The incubation period varies from 8 to 10 days. The young larvae move to cane roots after some initial feeding on grass roots. They are fully grown in 8 to 10 weeks' time when they move deeper into the soil and pupate in earthen cells at a depth of 0·3 to 1·5 m. The pupal period varies from 12 to 16 days and the pest overwinters in the adult stage. There is only one brood a year.

The adults are active at night and are attracted to artificial light and can be destroyed in large numbers with the help of light-traps. Collections from the foliage of trees and shrubs at night is an easier and better method of destruction. Trials with insecticides applied as sprays to the foliage of shrubs in cages to which adults were immediately introduced showed that a suspension containing 0·5 per cent. DDT was effective and was superior to one of BHC.

Replicated field trials carried out for the control of the larvae with various insecticides showed that BHG applied to the soil in a dust at the rate of 22·4 Ib. toxicant per acre was the most effective. This treatment, when applied-at planting time (February) had an adverse effect on germination; this effect was not observed when the application was made at the end of May. In subsequent replicated experiments, when BHC in a dust was applied in two instalments at the rate of 10 Ib. per acre at the end of May at the time of the rush of adult emergence, and in July, respectively, much better results were obtained without any adverse effect on the crop. BHC and other insecticides applied to the soil in sprays at 10 Ib. per acre at the end of May were ineffective.

Amongst varieties of cane grown at the Bank Farm, Dalmianagar, Co.935 and B.O.3 showed a greater tolerance of injury by the larvae than the others.

A Scoliid, Scolia aureipennis Lep., was observed to parasitise the grubs during September. The rate of parasitisation was only about 5 per cent.

A disease caused by a fungus, Metarrhizium. anisopliae, was also observed to occur in the adults. Affected beetles died within 4 to 6 days.

The common Indian toad (Bufo melanostictus) and the gecko (Gecko gecko) were seen preying on the adults in the evening when these were active. A number of birds, particularly the Indian crow (Corvus splendens) and mynah (Acridotheres tristis), also feed on the larvae when these are exposed during tillage operations.

During 1958–60, replicated insecticide trials were carried out in East Anglia in an attempt to assess seed losses on Trowse mustard (Brassica juncea) caused by larval infestations of the cabbage stem weevil, Ceutorhynchus quadridens (Panz.). The overwintered adult weevils invade the young growing crops during April and May, and the eggs are laid in the petioles over a period of weeks, depending both on temperature and crop stage, until about mid-June. Egg-laying began on mustard when the plants had produced six to seven broad leaves, but the actual time at which the first eggs were laid seemed to depend mainly on temperatures during May. In the insecticide trials, infestations averaged up to 26 larvae per plant, and none of the untreated plants entirely escaped attack.

High rates of γ BHC (5 or 10 per cent, of the weight of seed) gave some control of stem-weevil larvae when kerosene was used as the sticker for the insecticide; 3 per cent, or 5 per cent, phorate and 5 per cent. Telodrin (1,3,4,5,6,7,8,8-octachloro-3a,4,7,7a-tetrahydro-4,7-methanophthalan) gave no control. The control by seed dressing was unreliable and is considered unsuitable for assessing yield losses caused by stem weevil.

A single emulsion spray of dieldrin applied during May when the first adult feeding holes were found in the petioles, gave a good control of stem weevil and prevented egg-laying, and this technique seems promising for future work on damage assessment. It is thought, however, that sprays specifically directed against stem weevil would seldom be justified economically on commercial crops of Trowse mustard, but on April-sown crops the first dieldrin spray against blossom beetle, Meligethes aeneus (F.), may give some protection against stem weevil.

The damage-assessment experiments gave no reliable indication of the effects of the stem weevil on yields of seed, in spite of their being sited in localities known to have a high weevil population. It was clear, however, that sowing date greatly influenced yields of seed; plants sown in March outyielded those sown in April or early May.

When non-teneral male flies of Glossina pallidipes Aust. were caught concurrently on oxen and in Morris traps in two experiments in south-eastern Uganda and classified, within 1½ hr. of capture, according to a modification of the hunger-stage categories described by Jackson, individual recorders were found to differ markedly in their assessments. No conclusions regarding the hunger stage of flies taken by different attractants could therefore be drawn from the first experiment, but in the second, which was so designed as to discount possible bias amongst recorders, the proportions of ‘hungry ’ (stage III + IV) flies in catches of males were similar on variously coloured individual oxen, and generally higher than in trap catches, in which the proportions varied widely. As all the traps appeared identical, no generalisation is possible about the mechanism by which non-teneral male flies are attracted to and induced to enter such traps.

Experiments carried out in south-eastern Uganda, as part of a series of investigations of factors affecting the catch of Glossina pallidipes Aust. by Morris traps, showed that this was not significantly affected by varying the interval between emptying the traps within the range 1½-24 hours or by varying the width of the entrance slit from ¼ to 1½ inches. Such exceptions as occurred could be attributed to unexplained variations in the intrinsic performance of individual traps. Almost no flies were trapped at night (1830–0630 hr.).

Catches in traps with simulated defects (leaving the sleeve open or making holes in the cage gauze) were lower than in perfect traps; the catch was not significantly affected by the diameter of the sleeve opening, but was significantly lower in traps with 16 ½-in. holes in the cage gauze as against those with 2, 4 or 8. Escapes through such holes were observed whilst emptying the traps, when the recorder's approach disturbed the trapped flies, which were otherwise inactive. Frequent visits to the traps to empty them did not materially increase the number of flies effectively trapped, as might have been expected were flies escaping continuously or were the traps to catch flies accompanying the observer.

When the interval between emptying traps exceeded 24 hr., losses of trapped flies occurred, to an extent that is unknown but sometimes substantial, as a result of predation by ants; this is the most likely source of significant variation in catches made by apparently identical traps, and can be overcome by mounting traps on greased, single legs. When thus protected, there was no significant difference in catch between traps cleared at intervals ranging from 12 hr. to eight days. The longer this interval, the greater the proportion of dead amongst captured flies; the median length of life after capture was about two days, this period varying slightly with sex and more substantially with undefined differences between sites and trapping periods.

Gamma BHC, aldrin, dieldrin, endrin, DDT and parathion have been tested as seed dressings in field experiments for the control of wheat bulb fly, Leptohylemyia coarctata (Fall.), in eastern England. The concentrations ranged from 20 to 70 per cent, and the dressings were applied at 2–3 oz./bushel.

At concentrations of 40 per cent, or over, the first three materials appreciably reduced attack and at high infestations increased yield; within the period October to January their effectiveness increased the later the wheat was sown. There was evidence that they were less effective on highly organic soils. The other materials were either less effective or had other disadvantages.

Seed dressings of γ BHC usually reduced the number of larvae entering the plant but had little effect on larvae which succeeded in entering. Aldrin and dieldrin and probably most other materials usually had less effect on the entry of larvae but were very effective in killing larvae after entry so that the plant could subsequently recover.

Combine-drilling of aldrin or dieldrin affected the larvae in the same way as seed dressings; in one season on a peaty soil seed dressings were more effective than combine-drilling, but in another season on a mineral soil seed dressings were slightly less effective than combine-drilling. However, it was clear that with combine-drilling very much higher quantities of insecticide per acre were needed to achieve a comparable result. Both aldrin and dieldrin gave similar results.