These notes are the result of an examination of the literature and are concerned with geographical distribution. The Review of Applied Entomology, Series B, and the Tropical Diseases Bulletin were consulted and many papers were seen in the original; references to a selection of the more important of these is appended herewith. Of the ticks of the genus Ornithodoros occurring in the Old World about 40 names appear in published papers; of these about 20 seem to be valid species and five are well known and readily recognised: erraticus, lahorensis, moubata, savignyi and tholozani.

The chief aims of the survey and an important conclusion reached during some preliminary work are briefly stated. This latter was the recognition of two distinct nest types—the wet nest, exposed to rain, and the dry nest, sheltered from rain.

The methods used to examine materials and record results are described. They were closely similar to those described in a previous publication.

The insect fauna is listed under three headings: (a) ectoparasites of birds, which includes 12 species; (b) scavengers, including 66 species; and (c) predators, comprising 14 species. Figures are given for the frequency of occurrence and the abundance of the more important nidicole species, abundance being given as an arbitrary estimate. The importance of each as a pest is also briefly stated, and detailed records are given for uncommon or particularly interesting species.

The mite fauna is dealt with in a similar manner. It includes one ectoparasite, 10 scavengers and 11 predators.

The basic composition of nests and the temperature and humidity conditions within them are described briefly and the possible influence of these factors upon the nest fauna is discussed.

The species of the dry nest community are classified, according to their feeding habits, as ectoparasites of birds, scavengers and predators, and according to their status in the nest, as regular, occasional and incidental inhabitants. The distribution of the group of species which truly characterises this community is discussed.

The records and descriptions of Eriophyid mites hitherto described from tomato are discussed. A statistical examination was made of morphological measurements of the New Zealand tomato russet mite. The names of gall-mites occurring on tomato have been reduced to two: Acerialycopersici (Wolffenstein) 1879, the tomato erineum mite (causing the production of white, hairy patches on stems and leaf stalks); and Vasates lycopersici (Massee) 1937, the tomatorusset mite (causing stem and leaf bronzing). A key is given to the species of gall-mites occurring on solanaceous plants and several new combinations are recorded.

A description is given of a technique for breeding the parasite Spalangia drosophilae Ashm. (Spalangiidae). Various biological “constants” such as fecundity and longevity were studied at 70°, 75° and 83°F., and the variation in the figures for these is given. The oviposition rate, efficacy of single matings, sex ratio, percentage in diapause, developmental period of both male and female at the different temperatures are also give.

Laboratory spraying experiments were carried out with DDT, allethrin, the triethanolamine salt of 3:5 dinitrocresol (TDNOC) and HETP against eggs of different ages of Diataraxia oleracea (Lepidoptera) and with allethrin, HETP and TDNOC against eggs of different ages of Ephestia kühniella (Lepidoptera) and Dysdercus fasciatus (Hemiptera) under controlled temperature and humidity conditions.

Methods have been developed for breeding continuous supplies of Lygus vosseleri in the laboratory. Adults readily oviposit in cotton seedlings, but tend to damage the tissues by feeding, so that the eggs fail to hatch. Portions of developing sorghum heads were found more satisfactory; grains in the milk stage stay fresh long enough for eggs laid in them to hatch, if the ratio of adults to grains is kept low.

The method used was to expose sorghum grains to adult Lygus for 3–4 days, afterwards removing the grains to hatching cages to await emergence of nymphs. On emergence, nymphs were transferred to rearing cages and fed immature sorghum grains, changed every two days. Hatching and rearing cages consisted of muslintopped, celluloid cylinders fitting on to shallow tins containing moist vermiculite covered by plaster of paris in which small holes received the sorghum stems.

At insectary temperatures the incubation period averaged 8·4 and the nymphal life 16·7 days; adult females survived up to 57 days and production of nymphs per female per day ranged up to 2·95. The mortalty in the egg stage is not yet known:the growth of fungi on the sorghum grains during incubation causes losses. Mortality in the nymphal stages averaged 44 per cent. and occurred chiefly in the first stage, probably due to handling. Improvements to reduce losses are described.

Difficulties in maintaining continuous supplies of sorghum grains, caused by attacks of Atherigona on sorghum seedlings and of Contarinia on sorghum heads, can be overcome, respectively by the use of insecticides and by bagging the emerging heads.

Contarinia sorghicola was discovered in Uganda in 1951, the only previous African record being from the Sudan. The infestation started in September in early varieties of sorghum grown in observation plots and reached a peak onlate varieties and ratoons in early March, thereafter declining as parasitism, chiefly by Tetrastichus sp. and Aprostocetus sp., increased to reach 100 per cent. in April.

The life-cycle was normally 19–25 days, but between December and April diapause larvae were found; these all produced adults in early August, following a period of high humidity.

Midges morphologically indistinguishable from C. sorghicola have been bred from Eleusine coracana and from wild Sorghum verticilliflorum in Uganda, and the midge may well be endemic wherever wild sorghums grow. Enquiries show that midge damage to sorghum occurs in Kenya, Tanganyika and Nyasaland, and it is likely that all the mainsorghum growing areas of Africa will prove to be infested.

The possible occurrence of resistance is discussed.

The small, hooked epidermal hairs on french beans (Phaseolus vulgaris) may have a profoundly detrimental effect on colonies of Aphis craccivora. The hairs are present on the petioles, stems and undersurfaces of the leaves but are absent on the uppersurfaces of the leaves. They are most dense and therefore most injurious to the Aphids on the growing shoots. The Aphids' legs become impaled on the hooks and the results of the subsequent bleeding, starvation and exhaustion are decreased longevity and reproductive rate, high larval mortality, increased time of larval development and decreased size; this last factor is associated with a reduced fecundity. On some varieties of beans the hairs are less dense than on others and on these varieties the action of the hairs in inhibiting predators may be more important than their effect on the Aphids.

The following Coccid was first recorded as a probable new species of Saissetia by Dr. W. J. Hall in Nutman and Sheffield (1949, p. 437), who suggested that it might be regarded as a possible vector, should a virus be the cause of Suddendeath disease of cloves. Although further research has shown that this disease is not caused by a virus, the species is of particular interest in its relationship with ants and this has been the subject of a special study by M. J. Way (in press).

The taxonomy of a complex of parasites associated with mealy-bugs on cacao in Trinidad is dealt with. The descriptions of nine species new to science are given and species not new have been treated in comparable detail. Fresh taxonomic or other data have been given for some related species.

The inclusion of an aberrant Thysanid species of biological importance necessitated a comparative study of characters that have been used within this group. In this connection, Thysanid parasites of Tachinidae attacking moth larvae in sugar-cane were considered and found separable into three closely related species, two of which are described as new.

Onions and related crops are attacked by the onion fly, D. antiqua (Mg.), and by the bean seed flies, D. cilicrura (Rond.), and D. trichodactyla (Rond.). The eggs, larvae and puparia of the three species are similar in form, and the only morphological difference so far observed is in the number of processes of the anterior spiracles of the larvae. In D. antiqua the anterior spiracles have 10–13 processes; in D. cilicrura and D. trichodactyla, the immature stages of which cannot yet be distinguished from each other, the anterior spiracles have 5–8 processes.

Onion flies and bean seed flies have different habits and consequently the circumstances of their attacks differ. The onion fly is a specific feeder and its attacks are likely to be serious in spring and early summer. The bean seed flies are general feeders and attack on onions in spring is unlikely because the preparation of the soil, which attracts the flies, is usually completed before they emerge from the over-wintering puparia. Bean seed fly attack on onions is likely to take place in August when onions for bunching are sown. The preparation of the seed bed attracts the flies of the third generation from the surrounding crops and the soil may become heavily infested with larvae which subsequently destroy the germinating seeds. In August and September it is unlikely that young crops will attract onion flies from the mature crops on which they are established.

An atomizer, with controlling hygrostat, has proved to be a very satisfactory humidifier for raising the humidity of a large breeding room without lowering its temperature.

Simple laboratory methods are described for assessing the potency and persistence of insecticides. Some of the newer synthetic insecticides have been tested by these methods against seven arthropod pests of medical importance.

Initial potency was judged by the mortality of insects exposed to standard films of oil solutions of the compounds, on filter papers. The approximate order of potency of the samples tested was:—

γBHC>dieldrin>aldrin=pyrethrins>chlordane=DDT= “Pyrolan” =allethrin> toxaphene.

Residual action was judged by the mortality of batches of bed bugs exposed to films of the insecticides, at intervals up to six months after preparation. The approximate order of persistence was:—

dieldrin=DDT=toxaphene>“Pyrolan”>γBHC=chlordane=aldrin>allethrin, pyrethrins.

Preliminary experiments are described of applications from aircraft of coarse sprays and coarse aerosols. The experiments were carried out over dense forest areas containing the tsetse fly G. palpalis.

At dosages of 0·2 lb. per acre of the p,p'isomer of DDT, or 0·032 lb. per acre of the γ isomer of BHC, both the sprays and the aerosols were relatively ineffective, and significant kills were obtained only with the aerosols.

The sprays were ineffective not only because they did not penetrate the canopy, but also because the nominal dosage was in any case too small to produce lethal deposits upon vegetation.

Much of the aerosol was filtered out by the upper layers of the canopy. The meteorological conditions in the area were also unsuitable for the application of aerosols, and much of the insecticide did not reach the canopy, but was blown away from the treated area.

It is concluded that aircraft applications of insecticide against G. palpalis are wasteful of insecticide, and would be very costly if substantial reductions in fly population were to be obtained. If insecticides are to be of value in such areas, ground methods of applying them would be almost certainly more effective, and less costly.

An experimental attempt was made to produce a fly-free corridor through a belt of savannah woodland containing the tsetse fly G. swynnertoni.

An area two miles wide and four miles long was treated with a coarse spray of a 4·6 per cent, w/v solution of DDT in Shell Diesoline. The dosage per application was 0·5 gallons per acre, and seven applications were made, at intervals of approximately two weeks, so that the treatment covered two pupal periods.

The fly density had fallen to a very low level by the end of the experiment, and the area remained virtually free from flies for the subsequent two months. An examination of the data suggests, however, that the fly population was maintained largely by immigrant flies, and was certainly subject to wide variations, and it seems certain that the effect of the applications would have been considerably less upon a stable, self-supporting population.

The drop spectrum of the ground deposit had a mass median diameter of 0·35 mm., and the recovery of insecticide in the area was approximately 60 per cent. Leeward and under sides of obstacles did not receive a dose although in some cases dosages were obtained on apparently leeward sides, probably because of local reversals of wind direction.

The median lethal concentrations of some persistent insecticides as obtained by a filter-paper-impregnation technique for X. cheopis and P. humanus corporis are given. Their relative toxicity runs in the following order:—

Flea (adults): Gamma BHC > dieldrin > aldrin > chlordane > DDT > pyrethrins > allethrin > toxaphene.

Lice: Dieldrin > gamma BHC > aldrin > chlordane > pyrethrins > allethrin > DDT=toxaphene.

On flea larvae gamma BHC is 36 times as toxic as p,p'DDT.

On flea pupae gamma BHC and DDT powders and wettable suspensions are effective; further tests are required to determine their comparative toxicity.

On mud blocks (London soil) gamma BHC wettable suspension is only 3 times as toxic as DDT compared with 20 times on filter papers impregnated with oil solutions. This is probably due to the more rapid sorption of gamma BHC as well as the difference of surface and formulation.

In the field, at dosages of 2 gr. per m2 of 70 per cent. p,p′ DDT and i43 mg. of gamma BHC from wettable powders, BHC was superior to DDT as it gave a much better control of fleas (P. irritans) over the period of the experiment (24 weeks).

Field trials on body lice by dusting the clothes, while worn, with 40 gr. (per person) of dusts containing, respectively, 10 per cent. (70 per cent. p,p′) DDT dust and 0·4 per cent, gamma BHC, showed that BHC gave more satisfactory results than DDT.

The resistance of lice to DDT shown by Busvine in the local strain of Pediculus and the possibility of its occurrence among fleas may be one of the factors contributing to a better control by BHC.

It was found possible to develop artificially, by selection in the laboratory, a slight degree of resistance in X. cheopis.

Studies are reported on the extent and importance of competition amongst larval and pupal parasites of Oscinella frit.

In Ontario, 30–40 per cent. of frit larvae are parasitised by Hexacola in July–August and superparasitism is thus likely. Subsequent attack by Polyscelis may occur, but probably unsuccessfully.

Competition between the larval parasites and the pupal ecto-parasites Callitula and Spalangia is generally slight, because the former species is not abundant and the latter tends to select only healthy hosts.

Experiments are described to test the inter-relations of the three pupal parasites by exposing puparia of Drosophila melanogaster to two species simultaneously and in sequence.

When Callitula and Spalangia are allowed to oviposit simultaneously, the former is more successful when hosts are relatively few, but otherwise the two species are equally successful. When Callitula parasitises puparia recently exposed to Spalangia, equal numbers of the two parasites emerge, but in the reverse experiment Callitula is superior. Callitula is able to parasitise successfully a proportion of puparia already containing Spalangia whatever the age of the latter; mature Spalangia thus attacked are mostly killed.

Similar comparisons of Callitula and Spalangia with the endoparasitic Loxotropa show that Loxotropa is inferior to both the others, but that all three show marked avoidance of multiple parasitism.

In general, there is little interference between the various species in the parasite complex associated with the frit-fly.

The parasite complex associated with the frit-fly appears to be one that is very well balanced, there being little interference between the various species involved. Moreover, when, for any reason, one species does not attain its accustomed degree of parasitism, this is offset by an increase in the numbers of one or more of the other species.