The attractiveness of oestriol and of a sample L-lysine to females of Aedes aegypti (L.) was tested (a) in an olfactometer of the Wieting-Hoskins type, and (b) in a free-flight cage enclosed in glass. Similar results were given by both methods, L-lysine being the more attractive at higher concentrations, but oestriol retaining its attractiveness down to much lower concentrations. When 27 L-amino acids were tested in the free-flight cage, 16 showed significantly positive stimulation. Of these lysine was the most attractive, representing a group of 11 which carried CO2 in carbaminoyl or adsorbed form or in both; the other five, of which tyrosine was the most attractive, carried no CO2.

In investigations made in January to November 1962, Anopheles parensis Gillies was found biting man in large numbers in a zone near Malindi, Kenya, in which house-spraying with DDT had been carried out between March 1961 and October 1962. Densities were greatest just outside villages, less so on the verandah of a house and least indoors. In one open type of unsprayed house, however, moderately large numbers were caught. The monthly average catch per night by two men was greatest (over 200) outdoors in July and August.

Biting activity reached two peaks during the course of the night, catches in all situations being greatest during the two hours following sunset and the three hours preceding sunrise. The evening peak was highest in the outdoor catches, and the late-night peak in the indoor collections. A distinct influence of moonlight on the catches was observed, the early evening peak under certain conditions being greater during the moon's first quarter and the late-night peak during its last quarter.

Numbers of examples were caught biting cattle, but owing to the absence of large herds of stock it is believed that most feeding took place on man. The proportion of nulliparous females was 64 per cent, in the sprayed zone and 50 per cent, in an unsprayed village, and in the latter the nulliparous rate in females resembling A. funestus Giles (the majority of which would have been that species) was 24 per cent. No specimen of A. parensis infected with sporozoites was found in the sprayed zone. In the unsprayed village, no infected glands were found in a small series dissected. Thus no evidence was obtained that A. parensis was acting as an exophilous vector of malaria in the sprayed zone. Moreover, in view of the high nulliparous rate observed in the unsprayed area, this species is considered unlikely to be of any importance under normal conditions.

In Java, Brontispa longissima (Gestro) (Col., Hispidae) is represented by chr. var. javana Weise and in South Sulawesi (South Celebes) by chr. var. selebensis Gestro. The endoparasite Tetrastichus brontispae (Ferriére) (Hym., Eulophidae) attacks both chr. var. javana and selebensis. However, in Java, there are two distinct strains of chr. var. javana. In one strain (A-strain) the parasite completes its development normally but in the other (B-strain) the parasites usually die in the larval stage. The areas where each strain occurs have been demarcated.

In laboratory studies at Bogor during 1958 it was established that the lifecycles of the A- and B-strains were similar. T. brontispae completed its development from egg to adult in 15 to 21 days (16 on average) in A-hosts but died in the larval stage in B-hosts within three to four days. In a few instances parasites in B-hosts were able to complete their development, but generally the host died a few days after the death of the parasites.

In the laboratory, adult parasites attacked B-hosts as readily as A-hosts, although the former were not suitable for parasite development. Phagocytosis by encapsulation or melanisation was occasionally encountered but was not the usual cause of the death of the parasites.

The coffee leaf-miner Leucoptera meyricki Ghesq. is the most serious insect pest of Coffea arabica in Kenya. Until recently, sprays containing parathion, methyl-parathion or diazinon have been recommended for its control.

Field trials were carried out there during 1962 with these three insecticides and two others, fenthion and fenitrothion, that had shown promise in laboratory trials described in an earlier paper. The greater part of the investigation was carried out on the larval stage. Single-tree plots were used, arranged in randomised blocks, and sprays were in most cases applied by knapsack machines. Spraying in all trials was timed to coincide with the presence of large numbers of half-grown larvae. Suitable dates could be forecast because the generations of L. meyricki follow a denned cycle with a single stage dominant at any one time. Mortalities of larvae were assessed, four days after application of the insecticide, by dissecting freshly mined leaves selected at random. Where necessary, a spray of coarse droplets of a poison bait was applied before a trial in order to reduce populations of parasites and mortality due to them to a low level.

At a concentration of 0·02 per cent., a spray of parathion gave a. significantly higher kill than one of methyl-parathion. Diazinon, fenthion and fenitrothion were available as emulsifiable concentrates containing 60, 55 and 50 per cent, active ingredient (w/v), respectively. These were tested at equivalent dilutions. At a dilution of 1¼ pints concentrate in 100 gal. water (affording concentrations of 0·094, 0·086 and 0·078 per cent, active ingredient, respectively), which was the volume per acre required to give full cover, fenitrothion gave a significantly higher kill than fenthion or diazinon, there being no significant difference between mortalities achieved by the latter two insecticides. The addition of a supplementary wetting agent to sprays of fenitrothion increased kill significantly, as did a reduction in spray volume with fenitrothion and parathion. The possible reasons for this are discussed.

The field trials described generally confirm the results obtained in earlier laboratory tests and support the view that any insecticide which shows promise in the laboratory will also give good results in the field.

A small-scale trial on potted seedling coffee plants was carried out to test by the dipping technique the ovicidal properties of concentrations of parathion, diazinon, fenthion and fenitrothion equal to one-half or two-thirds those necessary to give satisfactory field control of mining larvae. Mortality of eggs varied with their age, but in all tests with the first three insecticides it exceeded 90 per cent. In a comparison between fenthion and fenitrothion, the former was significantly more toxic than the latter, which killed only 38·1 and 82·1 per cent., respectively, of eggs ½ and 5½ days old.

The correct timing of sprays against Leucoptera is very important and should follow about seven days after the peak of moth numbers.

The insecticides used in these experiments are considered in the light of the characteristics, which are listed, that are desirable in those to be recommended for the control of Leucoptera on coffee. Those recommended, with rates (Ib. per acre), are parathion (0·4), fenitrothion (0·9) and fenthion (1·0). Diazinon and methyl-parathion are no longer recommended.

The insecticidal activities of 13 triphenyltin compounds having the general formula (C6H5)3Sn X were compared with those of other organotin compounds and DDT by exposing adults of Sitophilus oryzae (L.) for 48 hours on filter paper impregnated with 1 per cent, solutions of the compounds in benzene, and by allowing larvae of Tineola bisselliella (Humm.) to feed for 14 days on pieces of woollen cloth impregnated with 1 per cent, by weight of the compounds. The triphenyltin compounds were ineffective as contact insecticides, virtually all the Sitophilus adults surviving, whereas all were killed by DDT. Their effectiveness as stomach poisons varied with the nature of the Group X, mortality after 14 days amongst the Tineola larvae ranging from 76 per cent., for triphenyltin thiophenoxide, down to zero, for hexaphenylditin. All except the latter and triphenyltin sulphide were highly effective moth-proofing agents, the weight lost by the test pieces being less than 5 per cent, of that lost by the untreated control. Tetraphenyltin afforded no protection against Tineola, but tributyltin oxide caused 100 per cent, mortality, apparently by contact action, since none of the test piece was eaten.

A method is described for continuous rearing of Distantiella theobroma (Dist.) in the laboratory at approximately 75°F. and 65 per cent, relative humidity. Adults were caged on young cocoa twigs, and the mated females transferred to cocoa seedlings for egg-laying; 24 hours after hatching, the nymphs were transferred to unripe cocoa pods. The egg and nymphal stages lasted about 14–16 and 23 days, respectively.

Brief notes are given on the distribution of 34 species of sandflies (Phlebotomus) recorded in Kenya. Mention is also made of two other species not so far known from Kenya but from areas close to its border, since these may ultimately be found within it.

The distributions of the 36 species in Kenya and bordering areas, based on published work supplemented by many unpublished records, are shown on a series of maps.

Cattle kept at the Latoli kraal of the Indian Veterinary Research Institute at Mukteswar in the Kumaon foothills of the Himalayas were heavily infested with the tick Boophilus microplus (Can.). In order to reduce the infestation, the animals were treated with BHC dusts every season for a number of years. In 1960, it was noticed that the treatment was not as effective as in the previous years. A series of concentration/response tests was therefore carried out in 1961–62 to see whether or not the tick had developed any resistance to BHC. Ticks collected from cattle in a village about five miles distant, where no acaricide had ever been applied, were used as the standard for comparison. BHC as a wettable powder was used to provide six different concentrations of γ BHC for engorged females and unfed larvae, respectively. Treatment was by appropriate dipping techniques. Analysis of the results showed that the population of B. microplus infesting cattle at the Latoli kraal had developed resistance to BHC. The LC50's of γ BHC for engorged females and unfed larvae, respectively, of the Latoli population were 0.5164 and 0.0182 per cent., and of the village population 0.0834 and 0.00069 per cent. This seems to be the first record of any species of tick developing resistance to an acaricide in India.

It was found that the mean number of eggs laid per tick in the control batches was higher in the village population than in the Latoli population and that the difference was highly significant.

The effectiveness of ten acaricides against Boophilus microplus (Can.) on cattle in southern Queensland, Australia, was investigated in 1960–63. Of infested cattle dipped in or sprayed with each acaricide, some were kept in stalls so that observations on ticks that survived treatment could be made, and others were grazed in tick-infested pastures in order to find the period of protection against reinvasion by larvae. Untreated cattle were also kept in the stalls to indicate the numbers of ticks occurring in the absence of treatment. The reproductive capacity, in terms of eggs and larvae produced, of ticks surviving treatment was compared with that of untreated ticks, and, for aldrin, dieldrin and the last four compounds mentioned below, the protective period in the field was compared with deposits of acaricide on the hair of the cattle as indicated by chemical and biological tests. For the last four acaricides, the effect on toxicity of artificially fouling the dip fluid was investigated, and also the relative toxicity of clean and artificially fouled fluids to ticks dipped in them under laboratory conditions.

The acaricides tested, and (in brackets) the concentrations used, were aldrin (0·05 & 0·1%), dieldrin (0·1%), carbaryl (0·2%), Boots' ED 12308 (0·2%), ethion (0·1%), Ciodrin (0·1%), coumaphos (0·02%), diazinon (0·05%), carbophenothion (0·086%) and dioxathion (0·075%). All were emulsion formulations except carbaryl and diazinon, which were used in wettable-powder form.

Daily collections of engorged adult ticks that fell from the stalled cattle provided clear-cut, though not quantitative, assessments of the effects of the acaricides. All the compounds tested gave a very high level of control, the only exception being the lower concentration of aldrin, and the reproductive capacity of ticks that survived treatment was negligible. With some of the acaricides, large numbers of surviving ticks fell in the first day or two after treatment, and some laid eggs; but the viability of the latter was invariably low. These observations emphasise the need to consider the reproductive capacity as well as the direct kill of parasitic ticks when assessing the value of acaricides. At the concentrations tested, nearly all the compounds allowed a few ticks to survive that were in the engorged-nymph stage at the time of treatment; these dropped off the cattle from the tenth day onwards and laid viable eggs.

The mean protective periods of the chlorinated hydrocarbons and organophosphorus compounds ranged from three to six days, but on individual animals periods from three to eight days were recorded. Amongst the carbamates, a mean protective period of seven days was recorded for carbaryl in summer, whereas the mean protective period of RD12308 in winter, when such periods are longer, was 12 days. In come cases, protection appeared to continue when deposits of the original acaricide could no longer be detected on hair samples, and reasons for this are discussed.

The influence of various factors, other than concentration, on the effectiveness of acaricidal fluids and on the results of tests was examined. Chemical and biological tests of hair samples showed that the acaricides persisted longer on stalled than on pastured cattle. Formulations affected the amount of toxicant deposited on the hair, and there was an indication that fouling of the dip fluid with soil and dung may, under certain circumstances, increase the amount of toxicant deposited.

Previous records and new data on trypanosome infection rates in Glossina morsitans submorsitans Newst. in Northern Nigeria are presented, and discussed in relation to the hosts fed on by this tsetse fly. The new observations were carried out in three areas: at Mando and Gamagira, both lying in a fly-belt north of Kaduna, and in the Yankari Game Reserve in Bauchi Province.

Infection rates were obtained by dissection of flies, and the trypanosomes were identified by their locus; the validity of this method of identification is discussed. All infections with Trypanosoma spp. were attributable either to the vivax group or to the conrgolense group; no brucen-group trypanosomes were identified. More than 260 flies from each area were examined during March 1962, at the end of the dry season, and similar numbers during October 1962, at the end of the wet season.

There was no significant difference between dry-season and wet-season infection rates in any area. Taking the two seasons together, the rate at Yankari (12%) was significantly higher than the rates at Mando (5%) and Gamagira (3%), which did not differ significantly. These contrasting infection rates could be related to the host species principally fed on by flies in the different areas as shown by blood-meal determinations. The lowest infection rates occurred where Suidae furnished a high proportion of meals (Mando, 51%; Gamagira, 67%) and Bovidae a small proportion (Mando, 16%; Gamagira, 9%). The high infection rate at Yankari was associated with a high proportion of Bovid meals (53%), especially from buffalo (Syncerus nanus) and bushbuck (Tragelaphus scriptus), and a lower proportion of Suid meals (33%). For the three areas the relationship between infection rate and percentage of Bovid meals was statistically significant.

The species groups of infecting trypanosomes showed further contrasts between the three areas which were unrelated to the total infection rates. At Gamagira, 81 per cent, of infections were congolense group, and this proportion was significantly higher than that at Mando (45%) or Yankari (37%). The differences could be related to the types of host from which blood-meals were principally derived. The highest proportion of congolense-group infections occurred where the highest percentage of meals came from Suidae (Gamagira, 67%), and lower proportions occurred at Mando and Yankari where Suid feeds were relatively fewer (51% and 33%, respectively).

These findings are discussed in the light of existing evidence on the factors governing infection rates in Glossina. It is concluded that, within the over-riding influence exerted by temperature through geographical latitude, infection rates are determined by the type of host that forms the principal source of food. In some populations of Glossina the influence of the nature of the main food source can be sufficient to obscure the general effect of temperature in determining the level of infection. Some of the reasons for these relationships are discussed.

Observations in three areas in northern Tanganyika on the day-time resting sites of adults of Glossina swynnertoni Aust. showed that the most important of these was the underside of branches of trees. The number of flies seen on this site represented about one-third of the total population as calculated from the apparent density, and about half of them were on branches 4–9 ft. above ground, 1–4 in. in diameter and at an angle of less than 35° from the horizontal. It is suggested that were an insecticide to be applied to branch sites within these limits, then, since any fly must make six or more flights in the first 18 days of its life, it would be expected to alight on a treated surface at least once in this period. Were a lethal deposit maintained for twice this period, plus the pupal period, control could be effected.

In an experiment carried out in 1963 on the control of Glossina swynnertoni Aust. infesting open bushland in northern Tanganyika, 3 per cent, dieldrin or endosulfan was applied to certain of the resting sites of the flies. These had been determined by previous observations and consisted of the undersides of tree branches between 4 and 9 ft. from the ground, with diameters of 1 to 4 in. and inclined less than 35° from the horizontal. Eradication was achieved in an area of 35 sq. miles at a cost of £42 per sq. mile. In a subsidiary experiment, G. pallidipes Aust. infesting the narrow forest bordering a seasonal river was attacked by spraying the vegetation on the river bank up to a height of eight feet. Complete eradication was not attained, due, it is thought, to removal of the insecticide by heavy rain, so that some newly emerged flies escaped exposure to a lethal deposit. The flies were, however, eliminated from the greater part of the river at a cost of £12.5 per mile.

Nine species of Cecidomyiid midges, including Contarinia sorghicola. (Coq.), C. andropogonis Felt, C. caudata Felt, C. palposa Blanch., Stenodiplosis sp., ? Lestodiplosis sp., Clinodiplosis sp., a species of Lasiopterariae and an undescribed species of Bifila, have been recorded from the inflorescences of cultivated sorghums (Sorghum vulgare) and related wild hosts. New morphological and other studies of this complex, involving the use of new techniques which are described, have elucidated the complex without recourse to biological testing.

Contarinia, sorghicola with which C. andropogonis and C. palposa are placed in synonymy, and a new species, Stenodiplosis sorghi, here described, are the only valid species which are primary feeders on cultivated and wild species of the genus Sorghum. Contarinia caudata is a distinct species reared from the grass Apluda varia. Contarinia gambae, a second species described as new, on the basis of specimens reared from the grass Andropogon gay anus, was formerly misidentified as C. sorghicola. C. sorghicola, S. sorghi and C. gambae are described and figured in detail. A species tentatively placed in Lestodiplosis and a species of Clinodiplosis are comparatively rare and of no economic importance. The record of a species of Lasiopterariae from a wild sorghum is believed probably to have been based on a misidentification of the host, and a species previously referred to as the ‘ 3rd Bifila ’ from A. gayanus has no real connection with the sorghum midge complex.

Precipitin tests were performed on 238 blood-smears made from Culicine mosquitos collected from natural resting places at three sites, in the area surrounding a village, in uninhabited forest, and at an uninhabited rock outcrop in savannah vegetation in Northern Nigeria. In calculating the percentages of blood-meals that were positive for the various animals, the following criteria were applied: all negative results were subtracted from the totals tested; in calculating mammalian, but not avian or reptilian, percentages, all records that referred to “mammal, weak smear” were subtracted; “unidentified mammal” was included in the calculations. Results showed that Culex pipiens fatigans Wied. (taken only in the area surrounding the village) had fed mainly on man (45%) and birds (36%), and while Aedes vittatus (Big.) (taken only at the rock outcrop) fed to some extent on both man (14%) and birds (18%), the majority of blood-meals (54%) had been obtained from the porcupine (Histrix cristata). It is thought that these feeds on man from individuals of Ae. vittatus taken at an uninhabited site may have been obtained from villagers using a road about 150 yd. from the outcrop. Ae. luteocephalus (Newst.) (the majority of which were taken in forest) also fed to some extent on porcupine (11%) and birds (16%), but the principal host appeared to be Bovids (74%). It was established for the first time that Uranotaenia mashonaensis Theo. (the majority of which were taken in forest) bites man (29%); mammals other than man and birds accounted for 29 and 24 per cent., respectively. Half of the blood-smear samples obtained from females of this species did not react to any antisera, and were classified as negative.

Pyrethrum spray-sheet collections in a small village in Northern Nigeria showed that there was no significant difference in the numbers of Anopheles gambiae Giles and A. funestus Giles caught at different times in the early morning. In this village, huts at the edge nearest to the only breeding site attracted considerably more adults than those further away from the edge, and some huts were consistently more attractive to mosquitos than others. There was a positive correlation between the numbers of A. gambiae and A. funestus in the huts. Although significant differences were found between numbers of mosquitos caught in the huts occupied by different numbers of people, no simple relationship could be discovered between the combined densities of the two species and the number of hut occupants. It is concluded that there is need for further investigations into the factors influencing densities of the Anophelines in village huts.

An account is given of seasonal changes in the incidence and relative abundance of a number of Phlebotomine sandflies which rest in termite hills in two widely separated areas of Kenya.

The annual pattern of rainfall distribution is shown to be of greater importance than the total precipitation in influencing the gross distribution and local abundance of many sandflies.

Kenya sandflies fall readily into ‘ perennial ’ and ‘ rainy-season ’ groups: the former have a wide distribution and appear to breed throughout the year. The distribution of the ‘ rainy-season ’ sandflies is relatively restricted, since these species are found almost exclusively in areas with a bimodal pattern of annual rainfall; it is suggested that they may survive the intervening dry periods in larval diapause. The length rather than the severity of the dry seasons is thought to be the limiting factor in the distribution of ‘ rainy-season ’ species.

Examples are given of the seasonal changes in structure of populations made up of several species sharing, in the adult form, the same termite-hill habitat.

The toxicity of naturally weathered deposits of 21 chemicals to larvae of the codling moth, Cydia pomonella (L.), was assessed by spraying apple trees in the orchard and testing samples of the fruit picked at various intervals after treatment. Each apple was placed in a separate glass container with one first-instar larva from a laboratory culture, and larval mortality and damage to the fruit (defined as removal of a portion of the skin) were recorded after three days in a constant environment.

The site of entry of the larvae was shown to vary with fruit size, calyx entries decreasing and side entries increasing with increase in the surface area of the fruit.

The relationship between larvicidal activity and age of the spray deposit for periods up to ten weeks after spraying is illustrated graphically; data are presented for fruit damage caused by larvae applied one and three weeks after spraying.

On the basis of larval mortality and fruit damage recorded in tests on deposits up to three weeks after application, a spray containing 0·1 per cent, carbaryl was the most effective, followed by 0·05 per cent, fenthion, while Bayer 5024, Zectran, DDT, DDD (all at 0·l per cent.) and 0·04 per cent, azinphos (as the methyl or ethyl homologue) were only slightly less effective. Deposits from 0·1 per cent. Kepone, 0·02 per cent, diazinon, 0·11 per cent, malathion, 0·01 per cent, parathion and 0·05 per cent, carbophenothion, dimethoate and ethion also caused 90–100 per cent, mortality when fresh, but were less persistent. Fresh deposits from 0·1 per cent, endosulfan, 0·04 per cent, dioxathion, 0·05 per cent, phenkapton, 0·02 per cent, phosphamidon, 0·2 per cent, lead arsenate and 0·6 per cent, ryania only killed 50–88 per cent, of the larvae, and their residual toxicity was proportionately low.

Heavy rain soon after spraying caused a large reduction in deposits from wettable powders but the accompanying reduction in larvicidal activity was shown to be greater in the case of carbaryl than for DDT or DDD.

The rate of development of six species of Bruchidae (Acanthoscelides obtectus (Say), Zabrotes subfasciatus (Boh.) and four species of Callosobruchus) attacking stored pulses was studied over a wide range of constant temperature and humidity and the rate of oviposition of five of them investigated over a range of temperatures at 70 per cent. R.H. and a range of humidities at 30°C.

A hatch of the order of 80 per cent, of the eggs of A. obtectus, which are scattered among stored seeds, was recorded over the temperature range 17·5–30°C. at both 30 and 90 per cent. R.H. and over the range 15–35°C. at 70 per cent. R.H. None hatched at 40°C. The optimum conditions for rapid development of the egg are close to 30°C. and 70 per cent. R.H., where the egg hatched in just under five days. The period to hatching is increased at both lower and higher humidities as well as at lower and higher temperatures. The optimum for the rapid development of the post-oval stages is also 30°C. and between 70 and 80 per cent. R.H., in which conditions the first beetle emerged 20 days after the larvae were placed on haricot beans (Phaseolus vulgaris), the mean developmental period to adult emergence being 22·5 days, or 27·5 days including the egg stage. No beetles emerged at 35°C. and few at 15°C. Low humidity and very high humidity retarded development.

The eggs of Z. subfasciatus and the species of Callosobruchus are stuck to the seeds, and data for the egg stage were not obtained separately. The optimum for the rapid development of Z. subfasciatus on haricot beans is close to 32·5°C. and 70 per cent. R.H., where the first beetle emerged in 23 days and the mean developmental period was 24·5 days. No adults emerged at 37·5 or 17·5°C. and few emerged at 20°C. or at low humidity at 35°C.

The optimum conditions for rapid development of the species of Callosobruchus are 32·5°C. and 90 per cent. R.H. for C. chinensis (L.), about 30°C. and 70 per cent. R.H. for C. rhodesianus (Pic), 32·5°C. and about 70 per cent. R.H. for C. analis (F.), and 32·5°C. and 90 per cent. R.H. for C. maculatus (F.). None of the species could complete development at 37·5°C. and all four fared poorly at 35°C. Two species, C. chinensis and C. rhodesianus, were able to develop at 17·5°C. and the other two at 20°C. The performances of all the four species on dried garden peas (Pisum sativum) were poor; all did much better on cowpeas (Vigna unguiculata). The rate of development was slower on garden peas, the percentage mortality was higher and the developmental limits more constricted. In addition, the developmental period in all conditions on garden peas was so variable that the mean gave an unreliable estimate of performance and the time to the first emergence was used instead. The shortest mean developmental periods in days recorded were 22·5 for C. chinensis, 23 for C. maculatus, 25 for C. rhodesianus and 27 for C. analis. The shortest developmental period for an individual bred in garden peas was 18 days for C chinensis, 21 for C. maculatus and 26 for C. analis.

The sex ratio was close to unity throughout. The developmental period of the female was slightly longer than that of the male in A. obtectus and C. chinensis, and also in C. maculatus when bred in garden peas but not when bred in cowpeas. At 30°C. on cowpeas, breeding in mass culture at a low density gave rates of development similar to those observed with isolated insects in the cases of A. obtectus, Z. subfasciatus and C. chinensis, but with C. analis and C. maculatus a large proportion of those bred in mass cultures grew much more slowly than did isolated insects.

On garden peas, more than 50 per cent, of the eggs of the species of Callosobruchus grew to the free-living adult stage only in the most favourable conditions. For these species on cowpeas, and for A. obtectus and Z. subfasciatus on haricots, over 80 per cent, completed development over a wide range of conditions. Normally most of the mortality was of eggs or very young larvae, but at high humidity (80–100 per cent.) and at low (22·5°C. and below) and high temperatures (32·5°C. and above) a considerable number of individuals died after completing larval feeding, some after pupating.

In all the species studied except C. analis, at emergence the female was on average heavier than the male by 0·75–1·25 mg. In Z. subfasciatus, the weight range of the two sexes at any condition rarely overlapped. Callosobruchus spp. bred from cowpeas were heavier than those reared in garden peas. The heaviest beetles were bred towards the bottom of the temperature range, at 50 and 70 per cent. R.H. The weight decreased slightly at 90 per cent. R.H., more markedly at low humidity, slightly up to 30°C. and more abruptly at higher temperatures.

The rate of development of C. maculatus at 30°C. was shown to be. relatively consistent on several varieties of cowpea, the mean developmental periods on the best seven covering a range of less than 2 days (22·1 to 23·8). This mean was a further two days longer (25·7) on the two remaining varieties. Only one seed (Phaseolus aureus) from a series of ten other legumes had a mean developmental period within this range, and only from this seed and from P. mungo, brown peas and the nine varieties of cowpea were 30 or more beetles bred from 50 eggs.

The lengths of the various instars of C. chinensis were determined by the dissection of samples daily, and some information on the pupae of C. rhodesianus was obtained by the use of soft X-rays.

All the five species used in oviposition experiments were short-lived and had very short preoviposition periods after emergence. All laid at a maximum rate after 2 or 3 days, the rate falling quickly at high temperatures and more slowly at low ones. The highest mean number of eggs laid was 100 by C. maculatus, 75 by C. analis, 70 by A. obtectus, 50 by C. chinensis and 40 by Z. subfasciatus. C. analis and C. maculatus laid best above 30°C., and A. obtectus and Z. subfasciatus at 25°C. C. chinensis laid most eggs at 22·5°C., but the performance up to 37·5°C. was only a little inferior and varied irregularly from temperature to temperature; it was poorest at 20 and 17·5°C. The higher humidities (70–100 per cent. R.H.) were most favourable for all species at 30°C.

Eggs of Z. subfasciatus laid at 15°C. did not hatch at that temperature, and likewise eggs laid at 37·5°C. did not hatch at 37·5°C. Very few eggs laid at 25°C. hatched at 15°C., but about half of a batch laid at 30°C. hatched at 37·5°C. Otherwise about 60 per cent, hatched at 20°C., nearly 80 per cent, at 35°C. and 80 per cent, or more at all intermediate temperatures. At 30°C. hatching was good at all humidities including 2 and 100 per cent. R.H.

The results given in published work are compared with those obtained in this work. The value of the results in determining the pest potential of these species is discussed, and suggestions for the most profitable future lines of work are made.

The larva of Hylemya arambourgi Séguy is an important pest of barley in Kenya; it attacks the shoots, causing death of the central leaf. Three to four shoots are destroyed by each larva, and an early, heavy infestation, under conditions of drought, may cause complete loss of the crop. Where a crop is obtained, the effect of an infestation on yield is difficult to assess, because climatic factors play a major part in determining ultimate figures.

The life-cycle is briefly described.

Trials with various methods of chemical control showed that only seed treatments were consistently effective. Other forms of pre-sowing treatment were ineffective at economic rates of application, while a spray applied after an attack had developed was of little value. Sprays applied prior to the development of an attack gave variable results but were usually ineffective.

The most satisfactory chemicals used as seed treatments were dieldrin and heptachlor. Aldrin and endrin were sometimes effective, while γ BHC, carbaryl, dimethoate and thiometon were ineffective. A formulation of chlordane was also ineffective, but this failure may have been due to poor dispersion on the seed. It is probable that the insecticide acted mainly as a systemic poison, since larvae rarely enter the soil before the time of pupation.

Both dieldrin and heptachlor were initially used at rates of 4·6–5·0 oz. of active ingredient per 100 lb. seed, but usually gave as good results at rates of 3·5 and 3·2 oz., respectively. Dieldrin gave a measure of control at even lower rates.

The prospects for cultural methods of control appeared slight. No evidence of varietal resistance was obtained, while the possibility of control by restrictions on the sowing season is ruled out by the lack of evidence of diapause and the probability that Pennisetum clandestinum and other Gramineae, such as Chloris gayanaand Setariasp., serve as alternative hosts. For the same reasons, it is considered unlikely that any change in the position of barley in the seven-year rotation would have any effect on the level of infestation.

Investigations of the natural history of the virus of Kyasanur Forest disease since its discovery during 1957 in Shimoga District, Mysore State, south India have concentrated much attention on ticks of the genus Haemaphysalis in the region, as virus has repeatedly been isolated from them.

Keys are provided for larvae, nymphs and adults of both sexes of the 14 species of Haemaphysalis that have been taken in the area, with supplementary comments on six other species of the genus recorded, or likely to occur, elsewhere in south India. Illustrations are given showing the characters of the larvae and nymphs that are used in the keys.