The ovarian cycle in Culicoides barbosai Wirth & Blanton and C. furens (Poey), two biting midges of considerable importance in Jamaica, was studied in the laboratory. In C. furens, a single blood-meal was sufficient for development of a substantial number of eggs; in C. barbosai, which took a relatively smaller blood-meal, very few eggs were matured (usually between 10 and 20 but sometimes fewer than 10), and some females failed to produce any eggs at all.

A high degree of gonotrophic harmony was observed in C. furens, but in C. barbosai the degree of harmony was low and a large proportion of the ovarian follicles degenerated; these differences may be associated with the relative size of the blood-meals of the two species.

The duration of the gonotrophic cycle (from feeding to the appearance of mature eggs in the ovaries) at 68, 77, 85 and 91°F. was 156, 104, 82 and 72 hr., respectively, in C. barbosai and 102, 59, 42 and 36 hr. in C. furens.

In experiments on the effect of temperature and carbohydrate feeding on egg production, temperature did not influence egg production in C. barbosai, and greater numbers of eggs were not matured by females given access to honey during the period of egg development. However, access to honey did increse the proportion of individuals surviving the period of egg maturation and also the numbers that mastured any eggs at all. Females of C. furens kept at 77°F. matured more eggs than those kept at 91 or 85°F.; access to honey improved survival, but its effects on egg production were inconclusive in these experiments.

Observations indicated that adults of both species are probably in the habit of taking carbohydrate food in nature.

Females of both species may be autogenous, though the proportion of such individuals varied considerably between populations from different breeding sites. Autogenous females of both species emerged from the pupa with ovaries already relatively well developed; in C. barbosai the ovarian follicles were in Stage IIB or III, in C. furens they were in late Stage IIA or IIB. Large numbers of eggs were matured by autogenous females of the former, and the same is probably true of the latter.

The egg stage is apparently of longer duration C. barbosai than in C. furens. At 68, 77, 85 and 91°F., most eggs of C. barbosai hatched on days 12, 6–7, 5–6 and 5, respectively, whereas at the three higher temperatures most eggs of C. furens hatched on days 4, 3 and 2. Percentage fertility varied between individual egg batches of both species.

Laboratory experiments carried out in Jamaica in 1963 showed that the number of eggs matured by blood-fed females of Leptoconops becquaerti (Kieff.) was only slightly increased when they were allowed access to a source of dilute honey during the subsequent period of egg maturation. A majority of the females imbibed some honey, and over half took large amounts; survival was better in groups given honey than in those not. The amount of fluid in the crop of field-collected females indicated that more than half had fed on nectar. In the laboratory, field-collected females took on average more than their own weight of blood.

During 1964–65, 1,646 newly emerged females of Glossina pallidipes Aust., 1,898 of G. palpalis fuscipes Newst. and 2,528 of G. brevipalpis Newst. were marked and released in an area on the north-eastern shore of Lake Victoria in Uganda so that, by examination of those subsequently recaptured, the relation between physiological and calendar age could be determined. In the light of the results, records of physiological age and trypanosome infections in large numbers of wild-caught females of the same three species caught in the same area in 1962–63 were examined, together with published observation on the animals on which they fed, and the effects of age and food-animals on the incidence of infections were investigated.

Physiological age was determined by examination of the reproductive system and was expresses as the exact or approximate number of ovulations that had taken place. Infections with Trypanosoma were classified as brucei-type, vivax-type or congolense-type, and the last two as mature (infective) or immature, according to the sites in which trypanosomes were found in the flies. All brucei-type infections were regarded as mature.

The relation between physiological and calender age indicated that the length of the ovulation cycle was 11 days in G. pallidipes, 11 1/2 in G. brevipalpis and about 15 in G. palpalis fuscipes, but from other evidence that the last figure should have been about 11 days it is considered that ovulation was retarded in the released females of G. palpalis fuscipes.

The incidence of mature vivax- and congolense- type infections rose with age in all three species, beginning for the most part when flies were about a fortnight old. Brucei-type infections were rare and were found only in flies more than about 35 days old; nearly all flies with such infections also had one or both of the other types. The incidence of immature vivax-type infections rose with age up to about 25 days and then levelled off, which suggests that all eventually became mature. Immature congolense-type infections were rare.

G. pallidipes had the highest total infection rate and G. brevipalpis the lowest. The percentage of order flies in the samples was, however, greater in the later than in G. palpalis fuscipes, which suggests that age is not the sole factor determining infection rate. Food-animals appeared to influence it, since the infection rates of the three species were proportional to the percentages of meals obtained from Bovids.

The age at which females were inseminated was lowest in G. palpalis fuscipes, greatest in G. pallidipes and intermediate in G. brevipalpis. Abnormal ovulation cycles were rare in wild-caught flies, and few females that from their age should have been pregnant were found with an empty uterus.

The rate of digestion, as reflected in the rate of excretion, on a blood-meal was measured in males of Glossina morsitans Westw. (subsp. orientalis Vanderplank) under identical conditions of temperature and relative humidity but varuing conditions of other factors. The rates of excretion in non-teneral males captured after feeding on bait-oxen in two different habitants were identical and were significantly higher than those of non-teneral field-collected males fed on guineapig in the laboratory. The latter excreated the meal more rapidly than non-teneral males that emerged and were fed on guinea-pig in the labortory. That the variations were not due differences in blood type was shown by feeding teneral laboratory-emerged males on different hosts; the rates of excretion of meals from different mammals did not significantly one from another. Teneral laboratory-emerged flies excreted more rapidly when fed on reptilian or avian blood than when fed on mammalian. The lower rate of excertion in laboratory explanations in terms of a metabolic uncoupliing and pre-feeding behaviour are described.

The susceptibilities to DDT and to dieldrin of one-day-old teneral examples of Glossina palpalis (R. -D.), obtained from pupae collected from the field, were measured in the laboratory in Nigeria by two methods, one recommended by the W.H.O. Expert Committee on Insecticides (1963) and the other described by Kernaghan & Johnston (1962).

Pupae were kept in dry sand at a controlled temperature of 78–79°F. and 70–80 per cent. relative humidity until the adult flies emerged, and the latter were then kept individually in 3 × 1 in. glass tubes. All exposures to insecticides were carries out at room temperatures. Five flies were exposed together for one hour in the W.H.O. method, and flies were exposed individually for 1 1/2 minutes in the other method. After exposure, they were kept in a cabinet at 78–79°F. and 60–70 per cent. relative humidity. Mortalities were assessed 8, 24 and 48 hr. after the end of exposure, but only the 24-hr. results are presented. Regression lines and values for LC50’s were calculated by the method of probits

The mortalities amongst untreated flies averaged 5.6 per cent. for males and 5.1 for females, the latter value being insignifiantly affected by the method used. Dieldrin was far more toxic than DDT to both sexes, and females were apparently more susceptible than males to both insecticides; it is suggested that females pick up relatively more of a given deposit because of their greater weight.

The slope of the regression line relating mortality to insecticide concentration was steeper for long exposures than for short ones; it is suggested that this comes about because some insecticide picked up by the flies is lost after they are removed from the treated surface, the loss being relatively greater when greater discussed, and it is concluded that exposure for 1 1/2 minutes is long for satisfactory assessment of susceptibility when continuous contact with the insecticide is ensured (as in the method used for this period), but that exposure for 1 hour, ensuring 100 per cent. mortality at some concentrations, is preferable for detection of resistance. Although mortality from an insecticide may not be completed until 72 hr. after exposure, observations 24 hr. after are considered adequate.

The relative merits of the two methods of testing susceptibility are discussed. It is concluded than the method of Kernaghan & Johnston, which involves less handling and therefore less stimulation of the flies, is the more precise. The impregnated papers available from W.H.O. are a convenient means of exposing flies to known deposits of insecticide.

Observations on the eggs of the predatory Mirid Blepharidopterus angulatus (Fall.), which plays a part in the control of Panonychus ulmi (Koch) on apple, were carried out in 1963–64. The eggs required chilling at 4.4 or 7.2°C. (40 or 45°F.) for 14–16 weeks to terminate diapause. The reciprocal of the time in days for the first eggs to hatch showed a linear relationship with temperature. The temperature at the threshold of development was found by calculation to be 4.7°C.; 409 day-degress C. were required for the first larvae to hatch and 727 for 50 per cent. of them to hatch. From this information and the daily maximum and minimum temperatures, the expected dates of first hatch at East Malling were calculated for the years 1958–64 and found to agree well with the dates on which the first larvae were observed in the field.

Cotton in Central Africa is subject to attack by numerous insect pests, and this has limited production. The pests include Diparopsis castanea Hmps., Heliothis armigera (Hb.), Earias spp. and Dysdercus spp. Methods of rearing these insects in the laboratory are described, preparatory to testing insecticides for their control. By means of an egg-dipping technique, the susceptibility of first-instar larvae of Diparopsis castanea to a wide range of insecticides was determined, and that of similar larvae of E. biplaga Wlk. to a smaller range. The most effective were methyl-parathion, carbaryl, menthyl-demeton, parathion, methiocarb, Zectran, isobenzan, endosulfan, BHC, endrin and phosphamidon. DDT was more effective against Earias than against Diparopsis, and toxaphene was relatively ineffective against both. Aftertakiing the mammalian toxicity of the insecticides and certain other factors into consideration, carbaryl, endosulfan, endrin and DDT were selected for further evaluation in the laboratory and the field.

Further tests of insecticides, mainly carbaryl, endosulfan, endrin and DDT, for possible use against pests of cotton in Central Africa are described. In laboratory tests in Rhodesia, carbaryl was the most effective against first-instar larvae of Diparopsis castanea Hmps. exposed on leaves, stems and bracts of effective against second-instar larvae of Heliothis armigera (Hb.), to which the insecticides were applied directly, and carbaryl the least.

When adults of Dysdercus intermedius Dist. and D. fasciatus Sign. were caged with treated bolls, carbaryl was the most effective, endrin the next and (against the former sp. only) endosulfan the least. Deposits on leaves from 0.5 per cent. sprays of carbaryl, DDT and endosulfan remained effective in dry conditions for two weeks, but application of 0.05–1.0 in of simulated rain reduced their effectiveness immediately, especially that of carbaryl. The effectiveness of deposits was also reduced by plant growth and was affected by plant habit; on a hairy variety the deposits persisted longer than on a glabrous one, partly because the hairs retained them and partly because they made movement of the larvae more difficult.

Since 1956, samples of Lucilia cuprina (Wied.) from many parts of New South Wales have been tested annually for signs of resistance to organophosphours insecticides, which are used there to prevent fly-strike in sheep. For tests, 0.1 μg. diazinon per fly was applied topically; this discriminating dose was twice that required to kill 100 per cent. of susceptible flies. In 1965, some of the flies in a sample from Dubbo, in central-western N.S.W., survived the discriminating dose. Sensitivity tests of the progeny of the survivors (DB strain) and of a normal susceptible strain revealed that the LC50 of the DB strain was about three times that of the normal one. Further tests established that a roughly similar change in sensitivity had ocurred to other diethoxy (dichlofenthion, fenthion-ethyl, bromophos-ethyl, parathion) and to dimethoxy (fenchlorphos, parathion-menthyl, bromophos) organophosphors compounds. The change was therefore non-specific and, since it was also small, is regarded as an example of tolerance rather than of resistance.

Subsequent field surveys in 1965–66 showed that tolerance of L. cuprina to diazinon was widespread in N.S.W. The possibility that resistant strains will be selected out by continued use of organophosphorus insecticides is discussed.

Differences between sexes in the duration of larval and nymphal quiescence in Ixodid ticks were investigated in Israel in the laboratory. In H. dromedarii Koch the larval quiescence of the male was, on average about 4 hours longer than that of the female, but in Rhipicephalus sanguineus (Latr.) no significant difference was found. In five species a statistically significant difference in the length of nymphal quiescence was found between males and females; in three of them, R. sanguineus, R. secundus Fel.-Muh. and H. dromedarii, that of the male exceeded that of the female by 1/2 to 1 1/2 days and in the other two, H. marginatum Koch and H. excavatum Koch, the opposite was found, the difference being 1·3 and 3·7 days, respectively.

Newly emerged and 3-day-old house-flies (Musca domestica L.) of a diazinin-susceptible and a diazinon-resistant strain were treated topically with diazinon or diazoxon and examined for symptoms of poisoning and recovery at intervals up to 5 hours and at 24 hours after treatment. The effects of the poisons varied with the age and strain of the flies and with the poison used. Most of the flies that became paralysed died, but some recovered, even after appearing to be dead. Of flies treated when newly emerged, more of the resistant than of the susceptible strain recovered from paralysis, and more recovered from diazoxon than from diazinon treatment. Recoveries were fewer amongst flies treated when three days old and occurred in appreciable numbers only amongst those of the resistant strain treated with diazoxon.

Histochemical tests on flies, treated with diazoxon showed a close correlation between inhibition of cholinesterase activity in the thoracic ganglion and the external symptoms of poisoning. Inhibition was slight in apparently unaffected flies, more extensive in severely affected flies, and total or nearly so in completely paralysed flies. Inhibition first appeared at the periphery of the ganglion and spread inwards to the centre. Flies that recovered from paralysis had normal or almost normal cholinesterase activity, partially recovered flies showed activity only in the central parts of the ganglion. Recovery of cholinesterase activity seems to occur from the centre of the ganglion outwards.

A Phycitine Pyralid associated with Sorghum cultivars (Kaffir corn, dura or Indian millet) in Uganda, Tanzania and Sudan, and also known from one example from Northern Nigeria, is described as new and is named Salebria mesozonella sp.n. Illustrations are given of the adults and genitalia of both sexes.

Anjeerodiplosis peshawarensis Mani is a serious pest in North India of the fruit of the country fig (Ficus carica), which is its only known host. The midges are abundant, hovering under the host tree in the mornings and at dusk, and breed throughout the year, except in the summer from April until the July rains. In this period newly formed fruits are not infested, but in other months scarcely 30 per cent, of the fruits remain free from attack.

Eggs are laid in fruits when they one week old, succulent, and of the size of a pea. The eggs are minute, hyaline, unsculptured, oval and pedicellate and occur in bundles of 16. Incubation takes three days in September and March and five days in December and January. In laboratory tests, average viability in January was found to be about 83 per cent.

The entire larval period is passed inside the figs, each of which may contain 200–300 larvae. There are four larval instars, which differ in size according to Dyar's law and in morphology. The first-instar larva is devoid of cuticular outgrowths and does not show spiracles; the second and third instars have nine pairs of spiracles and possess characteristic spines, warts and tubercles; the fourth instar develops the sternal spatula. The entire larval period lasts three weeks from the middle of August to October and four weeks in January and February. From the middle of April until the July rains, fourth-instar larvae remain inside the figs. When the larval period is three weeks, the first and second instars together and the third and fourth instars separately last about a week.

Full-grown fourth-instar larvae bore out of the fruit and drop to the ground, where they jump for some time with the aid of their sternal spatula. They finally pupate in the soil without forming a cocoon but become covered in a protective case composed of soil particles that adhere to the larval skin. Early fourth-instar larvae, which do not have a sternal spatula, if taken from the fruits, may also successfully pupate, and the pupal period is normal. This period is 10–15 days between July and November and 25–26 days in January and February. It is shortest (10 days) in the rainy season, when both temperature and humidity are high.

The pupa is obtect, creamy white and bears poorly developed cephalic horns and bristles, well developed thoracic horns and many spines and cuticular outgrowths. Mortality in the pupal stage is between 15 and 30 per cent.

Emergence of the adults invariably occurs in the early hours of the day. Two or three days before emergence, the protective case becomes detached piecemeal. Males emerge before females. The ratio of males to females on the day of emergence is 1:2 between March and December and 2:3 in January and February. Copulation starts soon after emergence and lasts from 60 to 90 seconds.

There is considerable overlapping of generations. On the basis of the time required for completion of the life-cycle in different months, it is calculated that seven generations are completed in a year.

A diet previously described for rearing Pieris brassicae (L.) was found to be very successful for rearing Mamestra brassicae (L.). Less than 5 per cent. of the pupae that formed entered diapause. The larvae can be much more quickly counted, examined and looked after when kept on the diet than when kept on cabbage leaves.

Late in 1962, Heteronychus licas (Klug) was recorded causing damage to sugar-cane for the first time in Nigeria. It had previously been known there only as an inhabitant of grassland and a negligible pest of yams (Dioscorea spp.). The damage to sugar-cane, which was first noted at an early stage in the development of a large commercial sugar-growing estate (the first in the country) in Nothern Nigeria, resmbles that caused by Lepidopterous stem borers; the young shoots and tillers are eaten away around soil level by the larvae and adults and are eventually killed (‘deadhearts’). The adults sometimes tunnel in the pith of older canes, but seldom kill them. Surveys on the estate in 1963–64 showed that damage by the beetle was becoming increasingly important. In anticipation that this might happen, field and laboratory investigations into the habits and life-historv of H. licas were carried out in the same two years, and the initial results are reported.

There is one generation a year. Oviposition took place in moist soil near the bases of cane plants from late October to December. In the laboratory, the average female laid 60–75 eggs over a period of 1–3 weeks, hatching occurred after 9–16 days and the three instars lasted successively 14–19, 15–24 and 20–25 days. Larvae were found in the field from November to March, but occured in large numbers only during January and early February, mostly within a depth of 1 ft. in the soil; only those in the second and third instars fed on the canes. Puation took place in a cell 112–3 ft. below the surface; the prepupal and pupal stages together lasted 23–31 days in the laboratory. In the field, pupae were most numerous in February and March and adults, which began to emerge early in March, reached their greatest numbers between then and May.

Evening catches at a light-source showed that H. licas had two flight seasons each year, a subsidiary (post-teneral) one in April-June and a main (pre-reproductive) one in October-November, separated by a period of inactivity. Egg laying follows the second, and the adults die. Factors influencing the behaviour of the adults are discussed.

There were marked seasonal fluctuations in the incidence of ‘deadhearts’ caused by H. licas; it was highest in March-June each year, lowest during the period of adult inactivity, and again high during October-November.

Larvae kept together in the laboratory inflicted mutual injuries, mostly ending in death, but the extent to which this occured in nature could not be determined. Five Carabid species were found preying on the larvae in the field, and one on the adults as well. The importance of these and other possible predators and of parasites for the control of H. licas is discussed.

Measures that could be adopted for control are reviewed the literature.

Data were obtained on survival and development of larvae of Distantiella theobroma (Dist.) on cocoa seedlings maintained under three water régimes, high (HW), intermediate (IW) and low (LW). Recorda were taken of plant growth and damage by feeding. The water régimes of some plants were reversed in the latter part to the experiment.

Larvae soon completed development on HW plants, but on LW plants a large number died, possibly because they were unable to take up fluid fast enough to offset loss by evaporation. There was intermediate mortality on IW plants.

Larvae took longer to develop on IW than on HW plants, probably because they imbibed nutrients at a reduced rate.

More larvae survived on LW plants that were regenerating after increase in water status than on plants that had received abundant water continuously. They fed mainly on the old wood and very little on the soft regenerative shoots, so were apparently favoured by some change in the peripheral tissues of the main stem.

On HW plants, nearly all feeding took place on woody or partially hardened tissue; newly flushing tissue was not fed on if it was growing normally. On IW plants, the expansion of new terminal leaves was often slow, and these tissues were then attacked by young larvae. This happened much more on LW plants, where the apical region was killed by persistent feeding. On all plants larvae older than second instar fed only on hard tissues.

Later effects of feeding were splitting of the wood where lesions had been made and sometimes the development of fungal infecdtions. The most severe infections occurred when the upper part of the old stem died back on LW plants that were regenerating after increase in water status.

The nutritional state of males of Glossina morsitans Westw. (subsp. orientalis Vanderplank) obtained by two different methods from four vegetation types at two contrasted seasons during 1964–65 in Rhodesia was assessed by determining their fat content, haematin content and size. The results showed that even in the hot dry season, when Brachystgia and Commiphora woodlands were leafless, the nutritional state was better in flies from these two vegetation types than in those from evergreen riverine fringe vegetation; in the rainy season, the difference persisted but was smaller. Only in Combretum bushland, which is sparsely wooded, did the poor nutritional state of flies caught in both seasons accord with the relatively inhospitable appearance of this vegetation type.

The total food-reserves (fat plus the fat-equivalent of haematin) were higher in flies captured on fly-rounds than in those captured on bait-oxen, but the difference was smaller in populations under nutritional stress, e. g., in flies from riverine fringe vegetation and Combretum bushland in the hot season, which suggests that the period of sexual appetitive behaviour in males is shortened under conditions of nutritional stress.

The implications of these results are discussed in relation to methods of control that involve discriminating between parts of the tsetse habitat.

The identity of the palm kernel borer in West Africa is established, its correct name being Pachymerus cardo (Fåhr.); a neotype is designated for P. bactris (L.), the type species of Pachymerus Thunberg; a new species, P. thoracicus, is described from Paraguay, and three new specific synonymies are made. A key in given to the species of Pachymerus, the definitive characters of all of which are described and illustrated.