The problem of insect infestation of stored export food commodities in southern Nigeria is discussed, and a list of insects is given. At the ports there is considerable cross-infestation between commodities produced in northern and southern Nigeria awaiting shipment.

Old sacks used for the storage and transit of groundnuts are responsible for the spread of insects to palm kernel and cocoa marketing centres in the south. After bulk shipments of a portion of the groundnut crop, sacks are repaired and distributed for the shipment of palm kernels and some of them may be used by fanners and brokers as service bags for the marketing of cocoa and local food commodities. The importance of disinfestation before distribution is realised, and a small fumigation plant is in operation at port.

Ephestia cautella and Lasioderma serricorne are the major pests of stored cocoa beans. Both originate in farmers' and brokers' stores which are rarely cleaned, and in which small parcels of low-grade beans may be retained for mixing with a following crop to conform with an exportable grade. Ephestia cautella also infests palm kernels, and the early abundance of adult moths in cocoa stores up country during the marketing season is considered to be largely due to the storage of palm kernels in the vicinity. The development of Ephestia larvae can be completed on the outside of cocoa beans, only germinated or damaged beans being penetrated.

Insecticidal treatments against Heteronychus consimilis Kolbe, a serious pest of wheat in Kenya, killed large numbers of adults and markedly reduced the damagedone by them. Subsequent damage by larvae was prevented.

The most effective of the treatments tested were aldrin at 7.2 oz. per acre applied with the fertiliser, BHC in the form of Mergamma A applied as a seed dressing at 3¼ oz. per acre, and BHC in the form of Agrocide 7 applied as a seed dressing at 3¼ lb. per acre. The best treatments resulted in considerable increases in yield and gave promise of effective practical control on a large scale.

An account is given of a survey of the sandfly fauna of Iraq made in 1949 and 1950. Two new species, one of which has been previously misidentified, and two new varieties are described, and brief notes are given on all the 12 species of Phlebotomus and Sergentomyia taken in the survey. A description is given of a male of P. palestinensis taken in Baghdad, as it differs from the male described from Jericho. Keys to the Phlebotominae in Iraq and neighbouring territories are included, together with a Table showing their distribution.

Relationship between distribution of human dermal leishmaniasis and the species of Phlebotomus is shown on a map, supporting the belief that P. sergenti is the principal, if not the sole, vector of oriental sore in Iraq.

The distribution of Sergentomyia is given in another map indicating that, in contrast to Phlebotomus, the individual species of Sergentomyia are confined to one or other side of the boundary between the Saharo-Sindian and the Irano-Turanian zoogeographical regions.

The biology of N. hololeucus, T. globulus, G. psylloides, S. squamosum and E. hilleri has been studied to estimate their potentialities as pests of stored products.

They are widely distributed and feed on a very wide range of foodstuffs of both plant and animal origin.

Adult life is usually longer than the development period. Oviposition extends over most of the adult life. In warehouses all stages of development are present together.

At 70 per cent. R.H. the developmental period (egg laid to emergence of adult from its cocoon) comprises: 12 to 21 per cent. as the egg stage, 52 to 70 per cent. as larva, 12 to 16 per cent. as pupa and 6 to 19 per centg. as adult in cocoon.

The mean lengths of the various developmental stages, including the larval instars, have been found under several sets of physical conditions.

The tick, Ornithodoros moubata, was named by Murray in 1877 as Argas moubata; his specimens came from Angola (Portuguese West Africa), where twenty years earlier, Livingstone had noticed that such ticks were common in native huts; but Murray's description was “quite useless” (Nuttall & others, 1908) and it was Pocock (1900) who first published a recognizable description of the species and distinguished between 0. moubata and 0. savignyi (Audouin).

The properties of two DDT suspensions of a new type, “Supona”-D and “Supona”-DB are described. These suspensions contain about 50 per cent. DDT or 39 per cent. DDT+ 13 per cent. technical BHC respectively in their concentrated forms, the active material being suspended in a complex colloidal oil-water system.

Experiments were carried out with “Supona”-D and a DDT emulsion containing about 30 per cent. DDT dissolved in a mineral oil phase for the control of Glossina palpalis. Both products were applied in dilutions containing 5 per cent. DDT.

Laboratory experiments with leaves of Camellia thea and Begonia sp. showed that the initial toxicity and stability in tropical sunlight of residues of “Supona”-D were somewhat less than those of the DDT emulsion. The resistance to rain, however, was better with residues of “Supona”-D.

An investigation was made into means of increasing the effectiveness of the usual DDT-containing residual sprays with a kerosene base.

The common house-fly, Musca domestica, was used as biological material.

It was found that there exists a distinct relationship between crystal size and residual toxicity. Finely crystalline residues from DDT solutions in volatile solvents, such as xylene, proved to be considerably more toxic than coarsely crystalline residues from DDT solutions in less volatile solvents, such as kerosene. Addition of small quantities of coumarone resin to a DDT solution in kerosene was found to reduce the size of the DDT crystals and to increase the toxicity considerably.

A method is described for the extraction of arthropods from soil.

Eleven soil samples from pastures in the neighbourhood of Moshi, Tanganyika, and at Kawanda, Uganda, yielded collections representing a population of 54,565 arthropods per sq. metre in the top 6 ins. of soil or, if three samples are adjusted in conformity with biological indications, of 38,417 per sq. metre.

Nine soil samples from coffee and cassava plantations and from fallow ground gave collections representing a population of 24,423 arthropods per sq. metre in the top 12 ins. (in some cases 8 ins.) of soil.

Twenty-five soil samples from a pasture near Cambridge, examined in a strictly comparable manner, gave collections representing a population of 90,238 arthropods per sq. metre in the top 6 ins. of soil.

It appears that the arthropod population in the uppermost 6 ins. of East African pasture soil is much smaller than, and only about half as large as, that in an English pasture.

The causes and consequences of the smaller arthropod population of tropical soil are briefly discussed, and a connection is suggested between the meagre arthropod (and earthworm) population and the large amount of ligneolis material found in the soil samples examined, This connection may also bear on the paucity of humus in some tropical soils.

Sir Rickard Christophers (1947) working at 25°C. and a relative humidity of 80–90 per cent. found female Aëdes aegypti to be attracted by a warm dry surface at 40°C., and to be unaffected by a moist surface at room temperature. The writer (1948), working at 28°C. and 50–70 per cent. R.H. (usually near 50 per cent.) found the opposite: a warm dry surface at temperatures from 36°C. to 40°C. had no effect, while a moist surface at room temperature exerted a quite definite attraction. The purpose of the present experiments was to test the hypothesis that the difference between the results obtained in these two investigations was due to the difference in the ambient temperature and humidity.

Repetition of the relevant experiments at 25°C, 85–90 per cent. R.H., and 28°C, 50–55 per cent. R.H., gave results indicating that temperature and humidity difference operating at the time of the experiment could account for part but not all of the discrepancy. There are indications that the remainder may have been a result of the conditioning effect of temperature and humidity differences operating on the insect prior to the experiment.

The results emphasise the need for a full description of the climatic conditions under which behaviour work of the type discussed is performed.