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.

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.

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.

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 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.

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.

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.

Recent investigations on the control of cheese mites in New Zealand have necessitated detailed biological studies of the species concerned. Experiments have been carried out on the physical ecology of the species, Tyrophagus longior, Gerv., Tyrolichus casei, Oudm. [Tyroglyphus siro, auct.] and Tyroglyphus farinae, Degeer. A technique has been developed whereby, under controlled temperature and humidity conditions, individual developmental records may be readily obtained for all stages of the life-cycle. This technique is one that may be modified for similar studies on small insects, such as Thysanoptera, Collembola, etc.

1. Aphidius granarius is an internal parasite of Myzus kaltenbachi, where the latter is found infesting corn crops in South Wales.

2. The emergence of the adult parasite is described. Mating takes place within two hours of emergence, the females may be mated with more than one male.

3. A brief description of the morphology of the egg, larval, prepupal and pupal stages is given.

4. The rate of reproduction of the females of A. granarius is high, with female: male as 12·9: 10. Unmated females always produce males.

5. The adult parasite under normal conditions lives for 21–27 days and flies readily under favourable meteorological conditions. Within limited areas dissemination may be brought about most effectively by mature parasitised apterae.

6. The factors limiting the effectiveness of the parasite are briefly described. The degree of control at the end of May in the field may approximate to 90 per cent.

Anopheles gambiae var. melas was first described by Theobald (1903), and at the same time Dutton (1903) recorded the breeding of A. gambiae in seawater. These two observations were not correlated, but most later workers have believed, with Evans (1931), that the melanic pigmentation of the variety was a direct and temporary response to brackish environmental conditions. They have therefore made no effort to distinguish between the two forms.

All the specimens referred to below were collected by Mr. A. F. Posnette in Trinidad, British West Indies, during December 1943 or in January 1944, and were sent by him to the Imperial Institute of Entomology, London, for identification, because some of them, he thought, were of importance in the pollination of cacao flowers. The majority (46) had been found actually in cacao flowers, and all but one of these were referable to the two species, Forcipomyia quasi-ingrami, Macfie (38) and Lasiohelea nana, Macfie (7). It was these two species which Mr. Posnette believed to be “of great economic importance in Trinidad as pollinators of cacao.” The single exceptional specimen, which did not belong to either of these two species, was probably a small example of Lasiohelea stylifer, Lutz. With these insects were sent a few (8) other specimens from moss on the trunk of a cacao tree. They were, however, quite different species, namely, an Atrichopogon, a Stilobezzia, and a Dasyhelea. The following notes may facilitate the ready recognition and further study of these small insects.