The Indian custom of placing metallic mercury with the grain in the storage container to prevent infestation by insects has been investigated. It is found to have a sound scientific basis as the presence of mercury prevents the reproduction of certain of these pests.

Experiments showed that the vapour of mercury was fully effective in preventing reproduction of the grain weevil (Calandra granaria), the saw-toothed grain beetle (Oryzaephilus surinamensis), the lesser grain borer (Rhizopertha dominica), and the Angoumois grain moth (Sitotroga cerealella).

Zinc and tin amalgams and calomel were less effective than metallic mercury.

The efficiency of a given weight of mercury is increased by subdivision, a process which increases its total surface area.

In order to determine the method of entry of a contact insecticide such as pyrethrum into the body of an insect, studies were undertaken which showed that:—

(a) The rapid penetration of the insecticide into the body cannot be effected through the cuticle.

(b) When a mosquito has been sprayed with a mixture of pyrethrum extract and oleic acid, the deposition of fat globules around the tracheal trunks is a characteristic feature; this suggests that rapid diffusion of the insecticide takes place through the tracheal wall.

(c) Experiments on flies with their spiracles closed indicate that the absorption of pyrethrum, either in the liquid and powdered states, was very slow. This fact indicates that normally pyrethrum enters the body through the spiracle.

In 1935, Dr. Anderson made a sleeping sickness survey of the Kudaru District of Zaria Emirate, Northern Nigeria, where he found a high incidence of the disease. In the extreme case of the small hamlet of Sambo, he recorded a 70 per cent, infection rate among the 43 inhabitants.

The writer followed up this survey with an entomological investigation in the late dry season, and paid particular attention to. this hamlet.

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.

Cow dung was found to be suitable for breeding M. domestica vicina.

The dependence of the duration of development on the temperature was investigated for all stages of development and could be suitably expressed by the formula of an equilateral hyperbola.

Adult longevity was studied under various conditions of temperature and humidity. The maximum length of life in captivity was found to be 106 days, the average being 20–30 days. As the temperature rises, longevity decreases. Above 20°C, life is longest at a relative humidity of 42–55 per cent., whereas below 20°C., a lower humidity (30–40 per cent. R.H.) is favourable.

Fertility was studied from the point of view of size of individual egg hatches and the frequency of oviposition.

The mean number of eggs deposited by a female fly per day of adult life does not depend on the duration of adult life and does not change considerably during life.

The following descriptions are based on material collected by Mr. H. E. Box in the Gold Coast, during his work on insect pests of the cocoa plantations, and submitted to me for identification by the Imperial Institute of Entomology. Owing to war-time difficulties in obtaining various scientific journals, it is not always possible to make certain that a species is undescribed, so that although Mr. Box has collected several others which may be new, they have not been described here for that reason. The species now dealt with, however, are of particular interest either from the point of view of new distribution or from remarkable structure or striking colouration. Type specimens are preserved in the British Museum.

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.

The sugar-cane scale, Aulacaspis tegalensis, Zehnt., has been known to exist in Mauritius since the year 1899, when de Charmoy recorded it for the first time in the Island.

The species was described by Zehntner in 1898 from Java on sugar-cane, since when little has been recorded of its geographical distribution. In 1921, Ferris recorded it from Formosa. In 1938, D. d'Emmerez de Charmoy, jr., called the attention of the planters of Reunion to the damage caused by this scale on sugarcane, and the author had suspected its presence there many years previously. In Java it was considered of minor importance by Zehntner in 1897. In 1911 Van Deventer drew attention to the damage it caused in Java, and in 1915 van der Goot recorded a serious infestation in the experimental cane fields of the Java Experimental Station. Apart from these records, it has not been reported from other sugar-cane growing countries.

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.

In November 1939, Mr. G. H. E. Hopkins, Senior Medical Entomologist in Kampala, reported to me that he, together with Mr. T. W. Chorley, had discovered Glossina nigrofusca, Newst., in Uganda. As G. nigrofusca is a rare West African species, this find was rather unexpected, and he asked me to check the identification. The exterior characters of the two specimens sent in were entirely those of G. fusca, but after dissecting the male genitalia of a West African G. nigrofusca, I could not but agree that the Uganda specimens were quite as like the latter species.

The giant mealybug, Drosicha stebbingi, Green, which occurs in Northern and Central India, was described for the first time in 1900. Observations on its life-history and control have been made by Stebbing (1899–1903) at Dehra Dun, Lefroy (1908) and Dutt (1925) at Pusa, Richards & Sharma (1934) at Cawnpore, and Misra & Rao (1938) at Benares. Savage (1914) investigated the respiratory system of the female. Hingston (1929) made observations in Central India. Beeson (1941) has briefly recapitulated its life-history and control. Though it has thus been the subject of investigation by a number of workers since 1900, the information so far collected is far from complete. No effective control has yet been devised, for the existing methods of combating it are directed towards preventing the fertilised females from descending the trees and entering the soil to oviposit, and this is after the damage has been done. Its habits, which have an important bearing on its control, have not yet been fully studied, and the present investigations were, therefore, undertaken in 1938. The results are presented in this paper.

A method for fumigation experiments has been worked out, and preliminary tests on 21 substances are reported. The dosage-mortality relationships of about 10 of these arc being worked out in some detail, while six have been chosen for practical tests. It is hoped to make reports on these two aspects later.

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.

The following is a description of a new mealy-bug occurring on cacao in the Gold Coast, which is reported by the collector, Mr. H. E. Box, to be one of the Coccid vectors (Ferrisia virgata being another) of the “swollen-shoot” virus disease of cacao.