The sprays containing pyrethrum were outstanding in their high toxicity to the tick, and should be used where spraying measures are employed until a substance is discovered of the same order of toxicity.

Of the dusts, pyrethrum powder was again, outstanding in its activity. If it is to be used, tests should be done beforehand to make certain that the sample is a good one.

Other dusts were tested because pyrethrum powder is likely to deteriorate rather rapidly in the field. Certain derivatives of phenol and naphthalene were active as fumigants. Although these substances would evaporate quickly in contact with the general atmosphere, they might have some use as soil-fumigants in the floors of huts. Other derivatives acted purely as contact poisons and yet were just too volatile to be lasting in the general atmosphere. Alpha-naphthylamine and 3-methyl.6-ethyl.phenol are examples. Of these two, the latter is more toxic, and it is possible that the substitution of a higher alcohol for the methyl or ethyl group would decrease the volatility but not the toxicity.

Specimens of a Stenodiplosis were received early in 1942 from Mr. A. Moutia labelled “no. 73, ex inflorescence of Stenotaphrum dimidiatum, Mauritius (Reduit), xii.1940.” In a subsequent letter, dated 25th May, 1942, Mr. Moutia stated that the midges were reared in the laboratory from material collected in the fields. He also gave the information that the grass, S. dimidiatum, forms about 40–50 per cent. of the pastures in Mauritius and, though its main mode of reproduction is by its root stock and cuttings, the dispersion of its seeds may to some extent help in bringing a profuse and thick layer of growth.

It is known that, in solutions of some organic solvents such as pyridine, chloroform, ethylene dichloride and acetone, rotenone changes by oxidation to various derivatives, giving the solution a characteristic yellow colour (Jones & Haller, 1931). There is an accompanying loss in toxicity. Now that various intermediate solvents for rotenone in oils are being studied, it becomes of interest to know the stability of rotenone in these solutions.

The paper describes small and large scale methods of fumigation which have been worked out for six fumigants. The conditions under which complete control of body lice and their eggs may be obtained are set out, and the relative uses of the two methods and the various fumigants are described. Four of the materials tested, methyl formate, ethyl formate, ethylene dichloride and methyl-allyl chloride are comparatively safe and pleasant to handle, but they sometimes demand rather heavy dosages of fumigant or long exposures, especially at temperatures below 20°C. Chloropicrin and trichloracetonitrile on the other hand have strongly irritating properties, but their toxicity to lice is also much greater. The methods have the advantage that some are very safe and all are simple, demanding no elaborate technique or apparatus.

During a general survey of malaria in Transjordan, which was carried out in the summer and autumn of 1942, the Anopheline here discussed was found to be widely distributed and often common. It was first seen as an adult female, then considered to be Anopheles (Myzomyia) turkhudi, Liston, 1901, brought from Amman, Transjordan, in May 1942 by Capt. H. F. West, R.A.M.C. It is of value to describe the present material and compare it with such descriptions of the other members of the turkhudi group as are available to me at the moment, though it is considered that in no respect does it differ widely enough from A. (M.) hispaniola, Theobald, 1903, to be accorded more than varietal rank within that species.

A continuous method is described of separating adult Silvanus surinamensis from infested tea by means of an apparatus involving three behaviour stimuli, namely, light, heat and mechanical activation.

1. A detailed technique is described for the routine determination of the carbon dioxide output of samples of grain. The concentration of carbon dioxide produced in the intergranular air during incubation for 24 hours at 25°C. is known as the “carbon dioxide figure” of the sample.

2. Suggestions for relating the carbon dioxide figure to potentialities for future storage are given. A high carbon dioxide figure indicates that the grain is unsuitable for storage.

3. The carbon dioxide figure is largely a measure of insect infestation of the sample and a table is given by which the numbers of various species of insects common in grain may be estimated from the carbon dioxide figure.

4. Theoretical considerations affecting the carbon dioxide figure are discussed as far as available knowledge permits.

5. Data obtained in the laboratory during development of the method are presented, and show it to give a useful measure of the amount of infestation.

This work forms part of the programme of the Pest Infestation Laboratory. Thanks are due to Dr. Lucas for making an independent test of the method and for allowing us to use his data.

During the campaign in Abyssinia and British Somaliland, the writer was able to collect a few Simuliid flies during the course of mosquito surveys. All the specimens collected were submitted to the late E. G. Gibbins of Uganda, who kindly determined them, and at his suggestion I record the four species found, as it is believed that these constitute the first records of these species from the two territories.

When an insect parasite successfully attacks a host in the natural environment, the criterion of success being the development of the parasite progeny to maturity, the species attacked is described as a “natural host.” Parasites are used in biological control work with respect to their natural hosts. However, when the mass breeding of parasites for field distribution has to be carried out, the provision of natural hosts in sufficient quantity is in many cases difficult or impossible, unless they can be easily obtained in large numbers from the field. But some of these hosts have only a single generation a year. Others live in the larval stage in parts of growing plants which cannot be satisfactorily handled so as to produce mass infestations; on the other hand, attempts to rear such insects on detached fragments of plant tissue often result in heavy mortality. Other hosts which are very satisfactory for parasite propagation in some respects, become very susceptible to epidemics of disease when kept in large numbers in confinement. Even without these difficulties, the propagation in the laboratory of large numbers of natural hosts is often tedious and expensive.

The most suitable methods of disinfesting clothing and bedding depend upon circumstances, such as the extent and importance of the pest infestation, the numbers to be treated and the facilities available. This paper describes investigations of heat and cold for killing lice which were undertaken with an eye to very different situations, viz., the heat treatment of bedding in London air-raid shelters and the possible use of winter cold in Eastern Europe during post-war relief. Nevertheless, the problems have one thing in common; the inherent difficulty of heat transference through clothing and bedding.

A method of rearing large numbers of Aëdes aegypti for the biological assay of insecticides is described. The larval food found to be most satisfactory was a breadcrumb infusion. Blood is necessary for oviposition (human blood is best), but the main batches of insects destined for spraying are fed on water, sugar and raisins.

This work is being carried out under a grant from the Medical Research Council. The authors are grateful to Prof. P. A. Buxton and Dr. V. B. Wigglesworth for advice and encouragement.

The genus of Pyralid (Crambid) moths to which Diatraea lineolata belongs is one of considerable size, containing fifty-one described species from the New World (Box, 1931, 1935a), and together with the Old World genus Proceras which, according to Tarns (1942), should be regarded as distinct from Diatraea, includes a fairly large number of major pests of cultivated grass crops in both hemispheres, the most notorious being D. saccharalis (sugar-cane moth-borer).

(1) Three insects, Tribolium confusum, Ephestia kuehniella and Dermestes vulpinus, have been grown at several humidities and the following factors have been determined: length of larval period; water content of food and of the freshly formed pupae; wet and dry weight of pupae and wet and dry weight of food consumed during larval development. The “net utilisation” of the food has been calculated as the ratio of dry weight of food eaten per larva to dry weight of pupa.

(2) At lower humidities more food is eaten to produce a given unit of body weight. The length of the larval period increases and the weight of the pupae decreases.

(3) More food is eaten at low humidities, because part of the food is utilised as water. As a consequence of this, the larva grows more slowly and its final size is smaller. It is shown for Dermestes at 30 per cent. and Ephestia at 1 per cent. R.H. that less than 32·9 and 7·6 per cent. of the water in the pupae can be derived from water ingested with the food.

The lice that infect man may be one or more of the three species, Pediculus humanus capitis, P. h. corporis or Phthirus pubis, and this paper deals with treatments for the first and last of these.

Most of this paper is occupied with the description of a method for evaluating the influence ol temperature, recorded in the field, on the rate of development of the eggs of a grasshopper (Austroicetes cruciata). When the conventional methods of temperature summation were used, important errors were introduced because:—

(a) The temperature in the environment of the insect may be different from the temperature in the meteorological screen.

(b) The arithmetic mean of the maximum and minimum temperature may not be an adequate estimate of the true mean temperature for the day.

(c) The relationship between temperature and the rate of development of the organism over the range of temperature used, was not linear.

(d) Development may proceed for less than 24 hours of each day.

♂♀. Derm black, with uniform dense grey scaling that has a coppery reflection.

Head separated from rostrum by a narrow bisinuate stria; frons depressed below the level of the eyes and separated from them by a deep incision on each side, obliquely striolate and with a deep median sulcus; eyes moderately convex, extended sharply backwards for about one-third of their length, the orbit not projecting on the hind margin. Rostrum very slightly longer than its basal width, widest at base, gradually narrowing for two-thirds its length and thence more rapidly; dorsum broadly depressed, with longitudinally confluent punctures and a fine median carina. Antennae piceous; scape slightly exceeding hind margin of eye; funicle with joint 1 nearly twice as long as 2,3–7 subequal, about as long as broad and slightly widening distally. Prothorax nearly twice as broad as long, unusually flat, being only gently convex transversely, widest at the strongly arcuate base, the angles of which project laterally, with the sides almost straight and rapidly converging anteriorly, the apical margin being deeply sinuate on each side behind the eyes; dorsum flat longitudinally in the middle, densely squamose, each scale covering a minute granule. Elytra ovate, broader in ♀, widely sinuate at base, which is marginate, with the lateral angles projecting outwards and forwards, and the sides sinuate behind the angles; the dorsal outline moderately convex, sloping at the base; the shallow striae containing close deep punctures, which show through the scaling though partly covered and disappear behind, where the striae become deeper; intervals almost flat, with minute inconspicuous recumbent setae. Legs piceous, with dense concolorous scaling and their lower edges with a fringe of stiff erect setae; front tibiae compressed, with the outer edge carinate and the external apical angle produced laterally, the spines on the apical margin much reduced; hind tibiae with the inner face flattened and sinuate on the apical half, the corbels bare and ascending the dorsal edge more than usual, with the upper end angulate. Venter squamose laterally, but clothed elsewhere with dense stiff suberect setae.

All the described species of Poëphila have come from West Africa. Jacoby, in describing Crepidodera zambiensis in 1899, considers that it should be placed in a separate genus, and I now place it in Poëphila. It is very close to his two species, P. costatipennis and fulvipes. These three species have the elytra blue. Including the new species now described, the genus contains five species.

The economic importance of Capnodis in Palestine is discussed; the various species and their hosts are enumerated.

The egg is described and its shell chemically analysed. It was found that potassium, calcium and magnesium are present as cations and chloride and carbonate as anions.

The effects of relative humidity upon the egg are discussed. It is pointed out that the egg is resistant to a low percentage, but succumbs to a high percentage of relative humidity. The rôle of the egg shell in this matter is important.

The effects of the temperature upon the eggs are discussed. Their development at various temperatures is calculated, and the Blunck formula applied. The mortality of the egg at high and low temperatures is shown in tables.

In Northern Nigeria many of the streams are choked with the Palm, Raphia sudanica, which affords excellent conditions for Glossina tachinoides. The mid-ribs of the palm fronds provide long, straight, light poles which are invaluable for roofing in a country where small straight timber is non-existent.

In areas where the palms grow to a good height, there is an important local pole-cutting industry which results in the cutters coming into close contact with tsetse. A high incidence of sleeping sickness is often associated with villages engaged in this trade. The usual solution of clearing the stream-banks of vegetation is obviously undesirable in these cases, and the following method of control has therefore been devised.

Drought is the only factor in the environment of the eggs of Austroicetes cruciata that is likely to cause a high mortality rate of the eggs in the field.

The eggs may be exposed to drought at various stages of their development. The probability of high mortality due to exposure to drought during the winter is considered to be negligible.

The probability of a high mortality rate due to drought when the nymphs are hatching is unimportant. From an analysis of the meteorological records for 50 years, it was estimated that high mortality rates from this cause may occur 12 times in a thousand years at Hawker and less frequently elsewhere in the grasshopper belt.

The eggs are exposed to the most severe hazards during the summer. An analysis of the meteorological records shows that severe mortality rates may have occurred as a result of drought in the summer from one to seven times during the 50 years 1891–1940, depending upon the district.