The cotton stem moth, Platyedra vilella (Zeller), was not known to occur in the United States prior to 1951. In August of that year, larvae of the species were found infesting hollyhock plants at Mineola, New York, by J. H. Maheny, a plant quarantine inspector of the port of New York. Adults were reared from additional material collected the following year, an indication that the species had become established. How or when P. vilella was introduced has not been determined, but doubtless it was only recently.

Several artificial media were tested in an attempt to eliminate the use of human faeces as oviposition and early larval habitats for breeding Musca sorbens Wied. in the laboratory. Eggs, laid on cotton-wool pads moistened with diluted milk or, preferably, on small quantities (10–15 g.) of human excrement, were transferred to the breeding medium. The best of those tested was a mixture of coarse wheat bran (120 g.) and diluted milk (240 g.), which yielded normal healthy larvae and adults. The average weight of a puparium produced in this medium was somewhat less than that of one produced in human excrement.

The inheritance of aldrin resistance in the Indian house-fly, Musca domestica nebulo F., was studied by making reciprocal crosses between individual as well as groups of flies of an aldrin-resistant and a non-resistant strain of the subspecies at 28±1°C. The offspring of all the families thus formed were tested by the topical application of constant-volume drops of various concentrations of aldrin solution in oil to the dorsum of thorax of groups of flies. Mortality counts were made 24 hours after treatment. The results obtained indicated a multifactorial heredity for aldrin resistance in M. d. nebulo. The phenomenon was found not to be sex linked.

The mosquitos of two villages on the Kenya coast were studied over a period of two and a half years, which included years of very light, average and very heavy rainfall. A survey was made of the species occurring in the bush and in the houses, and in addition 24-hour biting catches were done and window-trap catches were examined to obtain information on the movement of species in and out of houses.

Sixty five species were taken in net catches in the bush but only 19 were taken regularly; five (Taeniorhynchus uniformis (Theo.) and T. africanus (Theo.), Aëdes woodi Edw., Culex invidiosus Theo. and C. guiarti Blanch.) were abundant. In the houses, two species, C. pipiens fatigans Wied. and Aë. aegypti occurred regularly, the former being abundant and the latter not uncommon. Anopheles gambiae Giles and A. funestus Giles were seasonal; A. funestus appeared only after exceptionally heavy rain. The in-going window trap attracted only an occasional mosquito seeking shelter during the day and only six species were taken. Thirty species were found in the out-going trap but only seven occurred regularly. A. gambiae, A. funestus, T. uniformis, T. africanus and C. p. fatigans were most active during the hours of darkness, with the main activity in the four hours before dawn. Aë. aegypti had two waves of activity, in the four-hour periods before dawn and before sunset, respectively; the sunset peak was higher and the main activity probably occurred between 18 and 19 hr., as previously recorded for this species in Mombasa.

Thirty five species were taken biting in the 24-hour catches in situations designated bush, house and compound, respectively. The biting cycles of A. gambiae, Aë. aegypti and C. p. fatigans have been compared in the three situations. The biting rhythm of each species was much the same in the different environments but the time and magnitude of the main peaks varied. In the case of Aë. aegypti, which probably includes two different forms, there is a marked difference in the magnitude of the evening peak in the bush and house. The biting cycles in the bush are given for A. squamosus Theo., T. uniformis, T. africanus, Aë. fryeri, Aë. metallicus (Edw.), Aë. albicosta (Edw.) and C. antennatus (Becker) and their occurrence in the other two situations is noted. The cycles of T. uniformis and Aë. fryeri agree with previous findings, but that of T. africanus differs from other cycles recorded for this species by having the main biting after midnight. The remaining species were rare, but one catch of 274 specimens of A. funestus was recorded.

Resting mosquitos were more numerous in the second half of the year from August to December, a period of light rainfall and high temperatures. Biting mosquitos were more commonly taken, especially in the bush, in the second quarter of the year, during the main rainy season. The biting activity of some species increased in the houses in the second half of the year, when there are high winds, and biting in the bush was minimal.

Using laboratory tests described, the effectiveness of a number of insecticides on both larval and adult, fully engorged examples of the Blue Tick, Boophilus decoloratus (Koch), was determined. The results of tests using adult ticks were expressed as histograms of the percentage control exerted by varying concentrations of insecticides. The test using larvae was more sensitive and enabled results to be expressed as dose-response curves from which the LC50 could be accurately calculated. By comparing ticks from different localities in South Africa, resistance to a number of insecticides was demonstrated. Adult ticks from the farms Allandale and Ferndale in the East London district were three to four times more tolerant of sodium arsenite than were the sensitive ticks from Frankenwald farm near Johannesburg. Both larval and adult ticks from Ferndale and Allandale, when compared with Frankenwald ticks, were highly resistant to γ BHC, which conferred some cross-resistance to toxaphene, chlordane, dieldrin and aldrin. Ticks from Allandale, in addition to being resistant to sodium arsenite, BHC, toxaphene, chlordane, dieldrin and aldrin were highly resistant to DDT. DDT resistance conferred a cross-resistance to Dilan.

The organo-phosphorus insecticides tested, malathion and diazinon, were equally effective against all ticks.

Two kinds of equipment for measuring the reactions of insects to the olfactory stimuli provided by some common components of insecticidal sprays are described. One of these, consisting of a T-tube carrying a current of odorous air across the top and admitting insects up the stem, is new, can be used in the field, and gives rapid and reproducible evaluations. Tests with several species of Diptera showed that technical DDT, diesel fuel oil, and an auxiliary solvent containing methylated naphthalenes are all strongly repellent or contain strongly repellent components. Related species gave similar results with the two kinds of equipment. House-flies (Musca domestica L.) resistant to DDT were less sensitive than normal house-flies. The implications of these findings are discussed.

Previous descriptions of the flight season of the Garden Chafer, Phyllopertha horticola (L.), are inadequate. From a study of five seasons, 1948–1952, the general or mass aspects may be outlined for the English Lake District as follows:—

The flight season starts in May or June, depending on soil temperature. When population is low the season lasts 3–4 weeks, when high it may last 5–6 weeks. Reasons for this are given.

The flight season has two overlapping phases. In Phase 1, beetles swarm close over the grass sward from which they emerged. As the season progresses, Phase 1 gradually gives way to Phase 2, in which the beetles now swarm closely on the bracken, hedges and trees surrounding the pasture. In the absence of bracken, the whole of Phase 2 takes place on hedges and/or trees. In the presence of bracken, phase-2 activity at first occurs on all three (bracken, hedges and trees) but, for some obscure reason, hedges and trees are forsaken in favour of bracken about halfway through the phase. Roughly speaking, phase-1 activity can be seen for the first two-thirds and Phase 2 for the last two-thirds of the flight season, i.e., there is about 50 per cent. overlap of the phases. The overlap is clearly due to earlier-emerging beetles entering phase-2 activity before later beetles have completed Phase 1.

Normal activity (i.e., flying closely over, or running or walking upon, the vegetation) is governed by weather. Both temperature and light are involved. Beetles are most active in warm bright conditions and, indeed, will fly and run only when the sun is shining. In warm bright-overcast conditions, they merely walk around. In cold, dull-overcast conditions (with or without wind or rain), they do not stir at all.

Activity starts any time between 8 a.m. and 2 p.m. (G.M.T.) according to weather (earliest recorded start being 7 a.m.). The first day of the flight season is usually marked by a short period of activity, 1–2 hours, in the forenoon, even when weather conditions continue favourable into late afternoon. As the days pass the period lengthens until beetles are active up to about 4 p.m. (latest recorded finish being 4.30 p.m.). The longest periods of activity, 8 a.m. to 4 p.m., occur when the sun shines all day after the first week of the season has passed. As the season draws to an end the activity period shortens until on the last day it is one hour or less. In general, rather more of the activity time occurs before noon than after.

The curve of numbers of beetles to be seen during the daily activity period is described for both phases. During the time of overlap of the phases, the curves are complicated by a certain amount of two-way traffic between grass sward and bracken (or hedges or trees). In addition, throughout Phase 2 a small proportion of individuals leaves the bracken flying high, straight and very fast, i.e., behaves abnormally; these individuals are termed “bee-liners” and will figure in a later paper.

For about the first week of the flight season all beetles disappear into the sward at the end of the day's activity. After that, a growing fraction of each day's active population spends the whole night in full view on the sward surface, bracken fringe, hedges and trees. All these “dormitories” begin to be used at the same time, i.e., about three days before Phase 2 starts. Passing the night on the sward surface ends with Phase 1. Roosting on hedges and trees ends simultaneously with activity there (first half of Phase 2). The bracken fringe alone is used right to the end of the season. Between sunset and sunrise, from 15 to 90 per cent, or more of resting beetles fall from bracken, hedges or trees to the ground. Reasons for this are given.

Beetles begin to feed when they stop spending the night below the sward surface. They feed after the day's activity is finished, and up to 8 p.m. at the latest. Their food is the herbage, bracken frondlets, leaves, blossoms, fruits, etc., on which they come to rest for the night.

Cage experiments confirmed that, in the absence of natural enemies, populations of Aphis fabae Scop., attended on bean plants (Vicia faba) by the ant, Lasius niger (L.), multiply more rapidly than otherwise similar but ant-free populations. The average difference in numbers recorded, was about one-third, the maximum being 70 per cent. No doubling or trebling of aphid numbers as claimed by an earlier worker was ever recorded.

When the Aphids are attended by ants, their excretion behaviour alters and the normal dispersal of the apterae from the young apical growth of bean plants is considerably delayed.

No significant differences were found between the numbers of nymphs produced by individual Aphids from ant-visited and ant-free plants, respectively, living on leaves of the same age; but the numbers were significantly affected by the age of the leaf or part of the plant on which the Aphids had developed or were then feeding.

It is suggested that ant-attended aphid populations multiply more rapidly because most of the Aphids feed for a much longer time on young plant tissue where, presumably, their food supply is more nutritious.

An experimental control project against Simulium damnosum Theo. in Northern Nigeria using DDT in diesel oil as a larvicide is described. A description, together with a map, is given of the project area, some 1,200 sq. miles in extent, with a population of 32,000 persons, and it is emphasised that this was selected to provide information on the feasibility of control in an area not isolated from other fly foci.

Methods used in applying the larvicide to the rivers, which had rocky beds with rapids and falls, and assessing the effects of treatment are discussed. Applications were made at prearranged treatment points, weekly, for a period of 12 weeks in the dry season of two successive years, 1956 and 1957, and the post-treatment density of adult fly was assessed and compared in a Table and in histograms, with that existing in the year prior to treatment.

In the first year, a mean dosage per application of 1·4 p.p.m. of p,p′DDT applied over 30 minutes (S.D. = 0·5 p.p.m.) at each of four treatment points resulted in the clearance of all breeding for a distance of 15–23 miles below these points, and a reduction of adult fly density in the area of 96 per cent. as compared with pre-treatment density. But reinfestation of cleared breeding grounds was found to be rapid, these becoming repopulated with immature stages within six months in spite of a mean wet-season fly density of only 0·35 flies per boy-hour.

In the second year, with application of 1 p.p.m. of p,p′DDT for 30 minutes, results were less successful than in the first, although three additional treatment points were used with the aim of controlling a greater distance than in the first year, adult density being only reduced by an estimated 82 per cent. of that before treatment in the first year. The reasons for this are discussed, and the lower degree of control is attributed to the partial failure of the insecticide to reach the breeding sites owing to the exceptionally low state of the rivers.

The fly-rounds used in assessing adult density and the pre-treatment breeding sites and the positions of the treatment points are shown on maps. Detailed data from the fly-rounds are given in an Appendix.

With the exception of slight mortality among fish, thought to be due to accidental impediments to tbfi free downstream flow of the larvicide, no toxic effects on other organisms were observed.

The cost of treatment is given, and the results are discussed briefly in relation to the existing knowledge on control of S. damnosum. It is suggested that control by the application of larvicides in non-isolated foci is a practicable possibility, but that annual treatment might be necessary because of rapid re-establishment in cleared areas. The effect of control, of the degree obtained in this work, on the incidence of human onchocerciasis cannot yet be determined.

Twelve species of termites occurring in the British Solomon Islands Protectorate are listed, and an illustrated key to their soldier castes is provided. An analysis of the 114 records has been made in order to indicate, in a general way, the relative abundance of the various species. Notes are given on distribution within the islands, on habitats and nests, and on the occurrence of termites on coconut palms and in buildings. Damage to buildings is discussed and suggestions made for control measures applicable to local conditions.

Anthrenus verbasci (L.) (Col., Dermestidae) is a pest of dried animal materials and is widely distributed in temperate regions.

The effects of temperature and relative humidity on development have been studied. It is shown that the periods of incubation and pupation decrease with increase of temperature, the former from 54 days at 15°C. to 12 days at 30°C., and the latter from 89 days at 10°C. to 9 days at 25°C. Humidity differences have little effect.

The larval development is exceptional in that under constant physical conditions in the laboratory there is a rhythmical onset of the larval diapause, i.e., development is regulated into one or more cycles, each comprising a period of active growth followed by diapause. The length of this cycle under constant conditions is considerably less than a year. Larval development may extend over one or two cycles depending mainly upon the temperature. At low temperatures of 15°C., development extends over two cycles; at 20°C. and above, only one cycle is needed; at the intermediate temperature of 17·5°C., half the larvae require one and half require two cycles in which to complete their development.

When the larvae developed under constant physical conditions with malnutrition the rhythm of development was maintained, but the larvae tended to require an extra cycle for development compared with those fed on an adequate diet.

Under three sets of controlled alternating temperatures (ranging from 18 to 33°C.) the rhythm of development was similar to that which occurred in constant conditions at a temperature equal to the mean.

The number of larval moults increased both with temperature and the time spent as a larva. At the unfavourably high temperatures of 30 and 35°C., larvae moulted an excessive number of times; one larva at 30°C. moulted 19 times after the fully grown stage was reached; and, at 35°C., 30 per cent. R.H., 13 out of 20 larvae gradually decreased from about 5 mm. (the length when first put to 35°C.) to 2 mm., moulting a number of times in the process.

Under outdoor fluctuating conditions, the resting period in the cycle is extended, due to the winter temperatures prevailing for some time after the end of diapause. Active development commences again in the spring when the temperature rises, and in this way the cycle is synchronised with the seasons into an annual rhythm of development. The life-cycle under outdoor conditions may take one, two or more years to complete.

Field populations, developing both in attics of houses and under more outdoor conditions, pupated from January to May, the time of pupation being mainly dependent upon the ambient temperature prevailing after the termination of diapause.

Diapause is of value to A. verbasci because it induces a rhythm hi the life-cycle which synchronises with the rhythm of the seasons and ensures that the adults are present when the environment is favourable for their activity, i.e., during May and June when the maximum hours of sunshine favour flight and the preferred flowers are in bloom.

The mechanism by which the rhythmical onset of diapause is controlled has not been investigated.

An experiment on Geescroft field, Rothamsted, from 1951 to 1954, tested the direct and residual effects of BHC, DDT, aldrin and chlordane applied to control wireworms (Agriotes spp.) in wheat.

The treatments applied were BHC seed dressing at 2 oz./bushel of a dressing containing 20 per cent. γ isomer of BHC; BHC 3·5 per cent. dust, combine-drilled to give 3·8–4·0 oz. γ isomer per acre; DDT 5 per cent. dust, combine-drilled to give 7·5 lb./acre technical DDT; aldrin 1·78 per cent. dust, combine-drilled to give 3·56 lb./acre technical aldrin, and chlordane 5 per cent. dust, combine-drilled to give 5 lb./acre chlordane.

In the year of application, the first out of old grass, when wireworm attack was slight, the plots treated with BHC, aldrin and chlordane, combine-drilled, gave significantly greater yields than the control plots. In the following year, when wireworm attack was heavier, residual effects on yield were observed on plots initially treated with BHC, DDT, aldrin and chlordane, combine-drilled. In the third year, residual effects on yield were observed on the plots initially treated with BHC, aldrin and chlordane, combine-drilled.

No direct or residual effect of BHC seed dressing was observed.

The residual effects are closely associated with the effect of the treatments on the wireworm population.

The results are compared with those of previous experiments and the increases in yield from the various treatments are discussed briefly.

The larvae of Culicoides circumscriptus Kieff. are mostly negatively phototactic when extracted from mud and placed in water. Experiments show, however, that if kept without food over a period of time a large proportion becomes positively phototactic. The provision of food causes them to revert to a photonegative taxis which may be permanent as long as suitable food is given, or temporary if the food does not satisfy their nutritional requirements. On the other hand, the provision of a completely non-nutritive medium does not bring about such a reversion. The significance of this behaviour is discussed in the light of the habits of the larvae in the field.

Most of the experiments were carried out with batches of fourth-instar larvae, but in a few, third-instar larvae and fourth-instar larvae near to pupation were used. From the results it is suggested that the processes of ecdysis and pupation may bring about a reversal from photonegative to photopositive taxis independent of the need for food.

The significance of the behaviour of the larvae towards light stimuli is discussed in relation to their habits in the field. It is assumed that its function is to maintain the larvae on the surface of the mud while feeding and to drive them below when they have fed, and that some other type of tropism must initially drive them to the surface or keep them below according to their nutritional needs.

It is shown that the behaviour towards light stimuli of the larvae of C. maritimus Kieff. differs somewhat from that of C. circumscriptus and reasons are suggested for this.

A second series of experiments designed to throw some light on the food requirements of the larvae is described. In a discussion on the results of these it is shown that the larvae feed on material both on the surface of the mud and below the surface, and it is suggested that larvae which have fed on sub-surface food become positively phototactic when they require food from the surface and, having fed there, revert to photonegative behaviour. If, however, photopositive larvae have not previously had the opportunity to feed on sub-surface material they continue to act as completely starved larvae and remain photopositive in spite of their having fed on surface material.

The detailed constituents of the larval diet have not been worked out. The larvae appear to be detritus feeders, feeding mainly on vegetable matter and bacteria obtained on or below the surface of the mud, though green algae are not an important part of their diet. They are carnivorous on occasion but are normally not so when other food is readily available. They are selective in their choice of food and at least three factors, sapidity, texture and the size of particles, appear to influence this selection.