In 1923, Edwards described under the name of Taeniorhynchus (Coquillettidia) buxtoni four cotype females captured by Buxton in September 1922 at Huleh, Jordan Valley (Palestine). A few years later, some females of the same species (determined by Edwards) were found by Brumpt in Corsica (Galliard, 1928): the Mediterranean and southern distribution of this mosquito was confirmed by the record of Mansonia buxtoni in Syria (Parr, 1943). Lastly, Aitken (1954) captured in Sardinia and Corsica some adults of M. buxtoni and described the structure of the male terminalia. The early stages, however, have remained unrecognised, and we have accordingly been led to make a morphological study of the larva and pupa, the results of which are presented here.

The group of Anopheles barbirostris Wulp is shown to consist of some 11 closely similar species, five of which are described as new. Keys for identification are provided. The group is divisible into two parts, the subgroups of A. barbirostris and A. vanus Wlk.

Two (or possibly three) species in the barbirostris subgroup are disease vectors.

A. barbirostris sensu stricto is the commonest and most variable species of the group and has the widest range, occurring probably from India to the Moluccas excluding only Borneo and the Philippines. Larvae can be found in a variety of breeding places in still or slowly moving water. Throughout its range, except perhaps in the Celebes, it appears to be largely zoophilous and not a vector of disease.

A. campestris sp.n. is very closely related to barbirostris. It appears to be confined to the alluvial plains of coasts and deltas, and may be limited to the mainland of Asia. It is common on the west coast of the Malay Peninsula where it is anthropophilous and an important vector of human (and possibly also simian) malaria, and of filariasis due to the periodic form of Brugia malayi. It is probably at least a minor vector of malaria and filariasis in the plains of Thailand.

A. donaldi sp.n. is the principal member of the group in Borneo, and is locally common in Malaya where the larvae are usually found in more shaded places than those of barbirostris. In Borneo it is a minor vector of malaria and filariasis, and possibly in Malaya also.

A. franciscoi sp.n. is the Philippine representative of the barbirostris subgroup.

A. hodgkini sp.n. is widespread (Thailand, Indo-China, Malaya and Borneo), but seldom common. It is a species of the forest and forest edge.

A. pollicaris sp.n. is an uncommon but easily recognised forest species only known at present from Malaya.

The vanus subgroup consists for the most part of uncommon species having little contact with man and usually associated with forest. A. vanus sensu stricto occurs in the Celebes and Moluccas where it is common, and also in Borneo and the Philippines; A. barbumbrosus Strickl. & Chowd., replaces vanus in the western half of the archipelago and on the mainland; A. ahomi Chowd., is known from Assam; A. manalangi Mendoza is confined to the Philippines; finally there is an unnamed species in Ceylon with speckled legs which was previously identified wrongly as A. pseudobarbirostris Ludl.

Three years of research on Eurygaster integriceps Put., and other Pentatomoids associated with cultivated cereals in Middle East countries, covered many aspects of the biology and control of these insects. This report is concerned especially with the overwintering or resting period and certain aspects of the annual life-cycle and physiology of E. integriceps.

Up to now these aspects have been studied mainly in the U.S.S.R., and frequent reference has been made to this work. The main objective in the author's own research has been not to explore fresh fields but rather to ascertain whether conclusions reached by workers in Russia are applicable also in countries of the Middle East.

Typically, E. integriceps spends a relatively short active period in the cereal fields in spring and early summer, and the young adults of the new generation migrate in mid-summer to higher altitudes in the mountains, where they spend a few autumn months in aestivation, followed by a hibernation period during the cold months of late winter; they descend to the fields again in spring. A number of different overwintering areas were visited in Turkey, Iraq and Iran, and two were selected for special long-term studies; one was Karacadag mountain, near Diyarbakir in south-east Turkey, and the other Ghara-agadj mountain, in the Varamine district near Tehran, in Iran.

Some of the ecological characters of these areas were studied, including the vegetation and certain climatic factors; the latter included maximum and minimum temperatures and relative humidity, and were studied more intensively on Ghara-agadj. Special attention was given to the microclimatic conditions under the plants where the insects are actually situated.

Population density has been studied at observation stations at different altitudes in the overwintering areas. Two methods are described for estimating population density in terms of the number of insects per square metre. Certain plants are more suitable for shelter than others, and there is some evidence that different types of plants tend to be used more extensively for shelter in the aestivation and hibernation periods. The distribution of these plants affects local variations in population density.

Monthly estimates of density at different altitudes confirmed that there is a partial downward autumn migration which takes place in October on both Ghara-agadj and Karacadağ. Mortality was also estimated during these counts and found to be highest after aestivation, and to affect males more than females. This differential mortality, and also a difference in migratory behaviour between the sexes, brings about differences in the proportions of males and females at different times and in different places; an account has been given of the changes, both local and over-all, in sex ratio throughout the year, and in most cases the reasons for them can be understood.

Research has been carried out on certain aspects of the physiology of Eurygaster, with particular reference to the fat content and the condition of the internal organs (‘ morphofunctional condition ’) and the seasonal changes which they undergo during the year. Fat content has been extensively estimated by chemical analysis, and morphofunctional condition by dissection. The Russian method of forecasting the strength of invasions by reference to physiological condition is discussed; analysis of population changes on Ghara-agadj (where numbers were increasing) and on Karacadağ (where numbers were decreasing) suggests that the present work supports this system of forecasting in principle, provided it is maintained for long periods and the condition of the population kept under regular observation. Fat analysis has proved a more reliable method than dissection for assessing the physiological condition of the population. This condition is not in itself an adequate criterion for making forecasts, and a summary is given of other factors determining the future population density which should be taken into account.

In insecticide trials in Southern Rhodesia against the woolly apple aphid, Eriosoma lanigerum (Hsm.), using methyl-demeton (0·078 and 0·052 per cent. active ingredient), dimethoate (0·0625 and 0·0417 per cent. active ingredient), diazinon (0·0625 per cent. active ingredient) and malathion (0·1041 per cent. active ingredient) as foliar sprays, all insecticides gave good control of infestations above ground, but methyl-demeton and diazinon gave the best control, and treatments were followed by slower rates of repopulation.

Injecting the lower part of the trunks of trees 25 to 30 years old with ½ fluid ounce of a concentrate of a systemic insecticide, 50 per cent. methyl-demeton or 40 per cent. dimethoate, at a single point gave excellent control where that part of the sap stream supplying the aphid colonies was intercepted. By injecting with a spiral of small holes around the trunk using ½ fl. oz. 50 per cent. methyl-demeton, control of all aphids on the tree could generally be achieved.

Good control of subterranean aphid colonies on 15-year-old trees was achieved by the application to the soil of 4 gal. per tree of a fluid containing 100 cc. of a concentrate containing 75 per cent. of V-C 13 (O,O-diethyl O-2,4-dichlorophenyl phosphorothioate) diluted with water.

Biological control of E. lanigerum in Southern Rhodesia by the Hymenopterous parasite Aphelinus mali (Hald.), which was introduced in 1961, shows great promise.

No reduction in the amount of feeding or in the oviposition rate was observed when females of Rhyzopertha dominica (F.) were supplied with whole rather than with cut wheat grains. Although there was a marked reduction in feeding when females were supplied with cut grains of paddy and a further reduction when they were supplied with cut grains of hulled rice, the oviposition rate observed on these two types of grain was only slightly lower than on wheat.

The difference in the oviposition rates observed on wheat and rice may be due to a difference in the nutritional values of these grains or it is possible that the harder texture of the rice kernel limits the feeding rate of the female sufficiently to affect the rate of egg production.

Eggs are laid preferably in crevices and on rough surfaces rather than on smooth, and these preferences often overweigh the tendency shown by the female to avoid laying on the grain on which it is feeding.

The results of experiments on egg distribution in paddy are in agreement with Crombie's (1942) observation that females of R. dominica tend to lay all the eggs for a given day in one short period of intense ovipositing activity. Thus, although suitable oviposition sites may be numerous, if they are individually able to accommodate all the eggs laid on one day, eggs will usually be concentrated in fewer oviposition sites than are available.

Laboratory and field tests were made to investigate the acaricidal properties of Tedion (2,4,5,4′-tetrachlorodiphenyl sulphone) and Kelthane (l,l-di(p-chlorophenyl)-2,2,2-trichloroethanol) and to compare them with Akar 338 (ethyl 4,4′-dichlorobenzilate), malathion (in field tests only), lime sulphur and the organophosphorus compounds Rogor (O,O-dimethyl S-methylcarbamoyhmethyl phosphorodithioate) and Ekatin (O,O-dimethyl S-2-(ethylthio)ethyl phosphorodithioate) against the red spider mite, Oligonychus coffeae (Nietn.), on tea in Assam during 1958–60. The materials were available at the following concentrations of active ingredient: Tedion emulsifiable concentrate (8 per cent, w/v), Kelthane wettable powder (18·5 per cent, w/w), Akar 338 emulsifiable concentrate (25 per cent, w/v), malathion emulsifiable concentrate (56 per cent, w/v), lime sulphur solution (24–26 per cent, polysulphide), Rogor emulsifiable concentrate, (40 per cent, w/v) and Ekatin emulsifiable concentrate (20 per cent. w/v). Tedion was also available as a wettable powder (8 per cent, w/w) and Kelthane as an emulsifiable concentrate (18·5 per cent. w/v). In the laboratory, the first three and Rogor were usually diluted to 1 part in 500 with water, Ekatin to one part in 1,000 and lime sulphur to 1 in 40, but Tedion was also tested in some experiments at 1:750, 1:1,000 and 1:1,500. Using a single-leaf technique in the laboratory, 2 ml. of spray were applied to each leaf. Sprayed directly on to the eggs, Tedion and Kelthane gave equally good kills (97·7 and 90·7 per cent., respectively) and were more effective than Akar 338 (47·9%) or Ekatin (27%). There was some evidence that Tedion may be more effective as a deposit on which eggs are subsequently laid than as a direct spray. It also has a toxic effect on the eggs developing in the ovary, maximum effect (0·5 per cent, viability) being observed in eggs laid on unsprayed leaves on the second day after spraying of the female. The effect declined slowly towards the fifth day and by the ninth day had practically been lost. Rogor was not tested against the eggs. At the concentration effective against eggs, Tedion had only a limited effect (38·7 per cent, mortality) on nymphs and adults 24 hr. after application. However, in two laboratory trials carried out on potted plants to compare the toxicities of Tedion, Akar 338 and lime sulphur under these conditions and to ascertain the persistence of their effects against nymphs and adults, whereas Akar 338 and lime sulphur were significantly more effective than Tedion after 24 hr. at the concentrations used, after one week the effect of the two former showed little change, whilst that of Tedion had increased greatly, and after two weeks was significantly greater than that of Akar 338 in both trials and in one of them after four weeks. The effect of lime sulphur at four weeks was not significantly different from that of Tedion and was superior to that of Akar 338 in one trial. Kelthane, Akar 338, Eogor and Ekatin, and also lime sulphur, gave 100 per cent, kill of nymphs and adults 24 hr. after application by the single-leaf technique. Kelthane, Rogor and Ekatin were not tested for persistence of effect. In the field, all sprays were applied at 100 gal. per acre. The same dilutions of Tedion, Kelthane, Akar 338 and lime sulphur as were used in the laboratory were applied, giving rates of 2·6, 6, 8, and 100 oz., respectively, of active ingredient per acre. Malathion was diluted to 1 part in 500, giving 18 oz. active ingredient per acre, and Eogor and Ekatin to 1 part in 1,000, giving 6·4 and 3·2 oz. per acre, respectively. Counts of numbers of mites on leaf samples taken 3, 7 and 15 days and one month after application in two trials in 1959 and one in 1960 indicated that, at the concentrations used, Tedion, although at almost every count it had reduced the mite population by over 90 per cent., as compared with the control, was not consistently significantly superior to Akar 338, Kelthane and Rogor. There was some indication that Ekatin and malathion might be less effective than Akar 338, Kelthane and Eogor. Lime sulphur was effective for a period up to 7–15 days.

Details are given of the construction of an all-metal form of locust rearing cage which possesses several advantages over the more usual wooden type.

A technique is described for maintaining colonies of mosquitos belonging to the genus Mansonia, subgenus Mansonioides, which have root-piercing larvae and pupae. The colonies are maintained in the absence of living plants. The females lay their eggs on discs of wet-strength crepe paper floating on the surface of water in small 10 × 6–cm. containers. Sheets of the same paper, 14 × 10 cm., stand vertically in the larval infusion bowls and the larvae attach themselves to, and pupate on, these sheets of paper, which contain air spaces. The papers are changed three times a week and this ensures an adequate air supply for the aquatic stages. The larval infusion is produced by soaking pellets of a proprietary animal-diet (Diet 18) in water, at the rate of 20 g. pellets per 1,500 cc. tap water, allowing to stand 3–7 days and using diluted 1:5 with water. The infusion in each larval bowl is stabilised by a block of turf, and yeast is added three times a week; this ensures a continuous supply of micro-organisms on which the larvae feed. The pupae are removed whilst still attached to the sheets of paper, these being transferred to covered bowls, containing tap water and a turf block, in which the adult mosquitos emerge. Pupal mortality is found to be about 40 per cent. With this technique, monthly production of adults has averaged about 2,000 and 1,300 in two insectaries, but has continued to fluctuate between wide limits. The fluctuations have not shown seasonal periodicity, but the numbers produced per month in the two insectaries are correlated significantly, although the insectaries are managed independently. This may reflect variations in the balance of micro-organisms in the standard nutrient infusions used, which could affect mortality amongst firstinstar larvae.

Mosquitos in the genera Uranotaenia and Ficalbia seldom bite man. In Africa, only two species, U. alboabdominalis Theo. and F. plumosa, (Theo.), have been taken actually engorging on man, though others may occasionally alight on the skin.

Hodgesia cyptopus Theo. bites man freely in forest, bush and plantations near Entebbe, Uganda, and sometimes enters houses.

The bimodal nature of the biting cycle of H. cyptopus in certain series of catches led to an investigation of the daily march of light intensity near the forest floor. It was found that at least in some areas this is bimodal, with a midday period of lower intensity—a pattern reflected in the biting behaviour of various forest mosquitos.

Though always diurnal, the biting cycle of H. cyptopus varies in form from station to station. It is thought that light intensity is of importance, and that this species probably bites in or around the small splashes of sunlight which penetrate the dense vegetation.

A method is described by which candidate repellents can be rapidly screened and evaluated by comparing them with a standard repellent or with each other. Mosquitos are confined in a petri dish, of which the top is covered with mosquito gauze and the bottom lined with two semicircular filter papers, one of which is treated with a standard repellent, the other with candidate repellent. The dish is placed in an apparatus through which passes a slow stream of air of standard temperature and humidity. Counts of mosquitos are taken every half minute on and above the two halves of the petri dish, which is jarred after every second count to change the position of the mosquitos. A total of 40 counts is taken, the dish being rotated through 180° after the 20th count. The index of reaction is determined as the mean excess of position records for the candidate repellent over those for the standard one.

The initial effectiveness and the persistence of various repellents have been compared. In tests against Aedes aegypti (L.), the repellency of N, N-diethyl-m-toluamide and of O-chloro-N, N-diethyl benzamide did not differ, but each significantly exceeded that of dimethyl phthalate (DMP). The loss of repellency of DMP with time was approximately linear.

Attention is drawn to various aspects and applications of the method, and to its advantages, particularly for rapid screening of repellents.

Three methods of chemical control of Melanagromyza phaseoli (Tryon) on bean (Phaseolus) have been investigated, these comprising seed and soil treatments and spraying of the foliage.

Organophosphorus and chlorinated hydrocarbon insecticides have been tested, chiefly as seed soaks, in the control of the pest. Applied in this way, the former gave poor protection, whereas the chlorinated hydrocarbons, especially the cyclodiene compounds, aldrin, dieldrin, endrin and chlordane, gave adequate protection. Reduction of the period of soaking led to better germination of treated seed. When seed-borne diseases were present, soaking in water or insecticidal solution enhanced their incidence. Bean varieties varied in their response to soaking in water or the insecticidal fluids used, the germination of most varieties being adversely affected. Endrin 20 per cent, emulsifiable concentrate (E.C.) used at a dilution of 1:250 as a soak for six hours or at a dilution of 1:125 for three hours or 1:50 for momentary dipping or up to an hour's soaking, gave good germination and protection from M. phaseoli with the climbing bean variety Kentucky Wonder but reduced very considerably the germination of several other varieties.

Where soil was treated with various insecticides for control of M. phaseoli. pre-sowing treatment was more effective in protecting the bean plant from this seedling pest than treatment given after seedling emergence. Soil treatment with endrin did not induce phytotoxic symptoms in those varieties that were adversely affected when the seeds were soaked in emulsified solutions of endrin.

Foliar spraying with DDT 18 per cent. E.C. at one fl. oz. per gal., endrin 20 per cent. E.C. at 0·5 fl. oz. per gal. or parathion 46 per cent. E.C. at 2 ml. per gal. at weekly intervals up to the time of flowering was very effective in controlling M. phaseoli.

The efficient control of the pest obtained with pre-sowing treatment of soil or seed suggests that the insecticides concerned may have been acting systemically. Laboratory studies on the life-cycle of the pest in plants derived from treated and untreated seed show that endrin (which was the only insecticide studied in detail in this way) has a larvicidal effect when used as a pre-sowing treatment.

Investigations were undertaken in Jamaica to determine whether or not the application of malathion for the control of the West Indian cane-fly, Saccharo-sydne saccharivora (Westw.), disturbed the natural control exerted by Lixophaga diatraeae (Tns.) on its host Diatraea saccharalis (F.). It was demonstrated, by exposing caged adults of Lixophaga, that adults present in the field at the time of insecticidal application would be killed but because of the short residual action of malathion the reduction in the parasite population would only be temporary. A comparison of the degree of parasitism in sprayed and unsprayed fields did not reveal any evidence of reduction in the rate of parasitism. The extent of damage by Diatraea in sprayed fields was significantly less than in unsprayed ones and factors which might account for this are discussed.

A number of observations were made on parasites of certain Pentatomoids (sunn pest) attacking wheat in Middle East countries, during the course of other work on these pests. The principal host species studied were Eurygaster integriceps Put., E. maura (L.) and Aelia rostrata Boh. The data concern both Dipterous (Tachinid) endoparasites of the adult bugs, and also Hymenopterous (Scelionid) egg-parasites; the observations were made principally in central Turkey, and in the Varamine district of Iran. A few observations on predators were made also.

The data concerning Tachinids consist of host records for six species of parasites. In no case observed by the author did these parasites appear to be of great importance in reducing the numbers of sunn pest; the same is true of the few instances of predators recorded.

Observations were made on six species of Scelionid egg-parasites (five species of Asolcus and one of Hadronotus), five of which were bred from eggs of four species of Pentatomoid hosts collected in the field. The species concerning which the most comprehensive data were obtained were Asolcus rufiventris (Mayr), A. semistriatus (Nees) and A. vassilievi (Mayr). Egg-parasites are well known to be more efficacious in reducing sunn-pest populations, and A. semistriatus has been extensively used in Iran as a biological control agent. The data obtained enabled some ideas which are of importance for the use of egg-parasites in biological control to be formed and discussed. These concern principally (a) the susceptibilities of different hosts to parasitisation; (b) host selection by parasites; (c) the selection of a species of parasite most suitable for biological control in a particular area.

Recent records show the distribution of Empoasca devastans Dist. extends further to the east (to East Pakistan, Thailand and New Britain) than had been recorded formerly, and approaches that of E. terraeregine Paoli, which is restricted to Queensland. Figures of the male genitalia are provided, by which the two species may be separated.

Cryptolestes capensis (Waltl) has been reared successfully upon wheatfeed at constant temperatures of 15 to 32·5°C., at intervals of 2·5°C., and 90 per cent. R.H., and at 30°C. and 10 to 70 per cent. R.H. Newly formed adult males were found to weigh more than females bred under the same conditions. Oviposition was investigated at 90 per cent. R.H. and 17·5, 20, 30 and 32·5°C.; the highest rate was at 30°C. It was concluded that 30°C., 90 per cent. R.H. were the optimal conditions of those observed. Comparison with C. turcicus (Grouv.) which occurs in the same habitat as C. capensis, shows that the temperature limits of the former are higher, but that at those temperatures at which both species can breed, there is little, if any, difference between the total duration of the immature stages. At the observed optimum for the two species, C. capensis has a higher innate capacity for increase than C. turcicus. These observations do not account for the rarity of C. capensis in comparison with C. turcicus, and it is postulated that C. capensis is, like C. ferrugineus (Steph.), more susceptible to the harmful effects of high larval density than is C. turcicus.

Hofmannophila pseudospretella (Stnt.) is a very widespread and common omnivorous scavenger in Britain. It is able to digest keratin and, while rarely occurring in large infestations, has a nuisance value as a textile pest in dwellings. It is commonly found breeding in birds' nests and dry organic débris likely to be found in attics and roof spaces, and mature larvae wandering from the feeding site are probably the only cause of damage to domestic textiles which, according to our records, are principally carpets.

A method of maintaining cultures in the laboratory and obtaining standardised larvae for mothproofing tests is described.

Adequate protection against newly hatched larvae was given by 0·1 per cent. Dielmoth (25 per cent, dieldrin) and 1·0 per cent. Mitin FF (an unknown percentage of N-(3,4-dichlorophenyl)-N′-2-(2-sulpho-4-chlorophenoxy)-5-chlorophenyl urea, sodium salt), while six-week-old larvae were not controlled by 0·15 per cent. Dielmoth or 1·0 per cent. Mitin FF. No protection against larvae in the wandering stage was given by Dielmoth in concentrations up to 0·63 per cent, or by 1·0 per cent. Mitin FF.

Both six-week-old and wandering larvae were controlled by 5·0 per cent. Mystox B (20 per cent, pentachlorophenol) and the latter also by 4·0 per cent. Mystox LPL (100 per cent, commercial pentachlorophenyl laurate).

The ability of the foreign grain beetle, Ahasverus advena (Waltl), a reputed mould feeder, to breed on various foods under conditions not conducive to mould growth was investigated in a series of culturing experiments. At 25°C., on a diet of rolled oats and dried yeast, the lowest relative humidity at which successful breeding occurred was 65 per cent., although a few adults were produced at 60 per cent. R.H. Wheat germ proved a satisfactory food under these conditions and the addition of yeast or germ to cereal products enabled the species to breed in the absence of visible mould growth, which it failed to do on. the cereal products alone. Although thriving larval cultures developed with crushed, dead grain weevils (Sitophilus granarius (L.)) as food, they invariably died out without producing pupae. On oilseeds at 70 per cent. R.H., moderate breeding occurred on groundnuts, which remained free from visible mould, but little or none on copra, cocoa or palm kernels in the absence of mould.

It is concluded that most stored foodstuffs are deficient in some factor, present in adequate quantity in dried yeast or wheat germ, that A. advena requires for successful breeding and that, in the field, this requirement frequently limits the species to mouldy products, although direct damage to groundnuts at 30°C. and 70 per cent. R.H. is possible in the apparent absence of mould.

The work described in this paper forms part of an investigation into the conditions which influence the breeding of Pieris brassicae (L.) in captivity. Observations have been made on the behaviour of the females at the time of oviposition, on factors which influence oviposition, on the appearance and weight of the eggs and on their fertility and hatching.

Females which are ready to lay seek out green surfaces and, as they respond eagerly to plants from which they are separated by glass, it seems that plant odour plays little part in the attraction. Once they have alighted, however, the insects drum on the surface with their fore legs to test its suitability. Normally they lay only on plants which contain the mustard-oil glucosides, but they have been observed to oviposit on broad bean (Vicia faba), on which the larvae do not survive. Sinegrin applied to green paper stimulates the female to lay. Provided she is standing on an acceptable surface she will oviposit on any other surface, for example, filter paper or glass. The eggs are normally deposited on the under surface of the leaves. This is largely due to a preference for the physical underside but the insects also seem to prefer the morphological under surface of the leaf to the upper surface. When laying an egg, the female locates one previously laid with the tip of her abdomen and so builds up the regularly arranged batches.

The females lived and oviposited as well in small cages as in large cages. They laid more eggs per day, and more eggs in a batch, at 30°C. than at 20°C. Both numbers increased until the female was about six to seven days old and then declined. Oviposition occurs at low light intensities. Fertilised females laid very many more eggs than virgin females. Oviposition occurred two to three days after copulation, and most females oviposited six or seven times in eight days. The number of eggs laid by starving insects is low: it is higher for insects given water or one per cent, honey solution and very much higher for insects given ten per cent, honey solution. Sucrose solutions are as satisfactory as honey solution.

When first laid, the eggs of P. brassicae are yellow in colour and become more orange as they develop. Some batches of newly laid eggs are of a distinctly darker yellow than others but, as it is believed that the eggs are fertilised only just before oviposition, it seems that this colour difference cannot be due to the eggs being in somewhat different stages of development. The number of ribs on the shells seems to vary in different cultures.

Batches of eggs which are laid within an hour of each other may begin to hatch several hours apart, and the time taken for all the eggs in one batch to hatch was found to range from two hours to about seven. A fertilised female lays scarcely any infertile eggs. The fertility after one mating falls below 100 per cent, after about 14 days, but normally the female mates again before this time. Temperature naturally affects the time taken by the eggs to hatch. The shortest time was about 3¾ days at 28°C.; the longest observed was 17 days at 12·5°C.

The eggs cannot be stored for more than ten days at 3·5°C. and 50 per cent, relative humidity. Eggs will develop and hatch at very low humidities. If the eggs are detached from the surface on which they are laid by the use of acetone their capacity to develop and hatch in air dried over phosphorus pentoxide is substantially reduced.

In tests of acaricides for the control of a Tyroglyphid mite, Aleuroglyphus ovatus (Troupeau), infesting cultures of the oriental rat flea, Xenopsylla cheopis (Roths.), in jars provided with linen covers and containing Purina dog food in sand as the rearing medium, Tedion and Kelthane proved ineffective, but light infestations (100 cc. of medium inoculated with 500 mites) were satisfactorily controlled by chlorobenzilate at 0·2 p.p.m. in the rearing medium or as a 0·05 per cent, solution in acetone painted on to the inner wall of the jar and used to soak the linen cover for three seconds. Heavy infestations (100 cc. medium inoculated with 2,000–3,000 mites) were controlled by chlorobenzilate at 20 p.p.m. in the medium or as a 0·5 per cent, solution applied to both the linen cover and the inner rim of the jar; a combination of both treatments (using 2 p.p.m. and a 0·5 per cent, solution) gave adequate control for 30 days.

The flea larvae were unaffected by 2 p.p.m. chlorobenzilate in the rearing medium; 20 p.p.m. killed larvae, but not adults. Neither stage was affected by treating the linen cover and inner rim of the breeding jar with a 0·5 per cent, solution of chlorobenzilate.

Measures are recommended for maintaining flea cultures free from mites, based on these experimental results and on a year's practice.

A sampling apparatus suitable for studying fluctuations in populations of the poultry red mite, Dermanyssus gallinae (Deg.), under field conditions is described. Four small infested poultry houses were sampled regularly for four years. In three of these years the highest population of the mite was recorded during August, and was followed by a fairly rapid fall in numbers during the autumn. Very few mites were found during the winter months. Attempts were made to increase winter populations by raising the temperature and humidity to August levels and also by increasing the amount of illumination during the winter months, but were unsuccessful.