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.

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 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.

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.

(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.

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 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.

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.

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.