The highlands of Abyssinia are remarkably free from blood-sucking flies, if the Culicidæ, Stomoxys, and Hippoboscidæ are excepted.

The inheritance of white eye in Lucilia cuprina (Wied.) was investigated by means of a series of back-crosses repeated through ten generations. Since an approximate 1:1 ratio of white-eyed: red-eyed flies was observed throughout, it is concluded that white eye is due to a single recessive gene (w). Earlier work establishing that w is on an autosome is discussed.

A test for the existence of a linkage group containing genes for white eye and dieldrin-susceptibility was then made. The exposure of back-cross progeny to discriminating levels of insecticide, and the pattern of mortality observed with scalar concentrations of dieldrin, indicated that genes for white eye (w) and dieldrin-susceptibility (rdi) are on different chromosomes.

Pyrgomorphella arachidis, sp. n.

♂ (Type). Of medium size, slender, finely rugulose.

Antenna of 17 segments, shorter than head and pronotum together, thick, slightly flattened and scarcely broadened at the base. Fastigium of vertex long, parabolic, ratio of its length to the width between eyes, 1·8. On the lateral sides of head behind the eyes there is a series of callosities forming a longitudinal stripe, which continues on to the lateral lobe of pronotum.

Investigations undertaken by the writer involved the determining and sexing of a large number of fleas daily, and it became clear that this would be a laborious process unless an apparatus could be designed which would facilitate separation and examination of the insects by making the process as automatic as possible. The technique finally used, though designed primarily for handling fleas, could be adapted for use with other insects of comparable size where examination under magnification is necessary.

All the leaf-feeding sawflies on Larix in Britain belong to the Nematine Tenthredinidae. Up till a few years ago, the most notorious recorded in this country was Pristiphora erichsonii (Hartig), though local attack of P. wesmaeli (Tischbein) and P. laricis (Hartig) have also occured. These are also the chief Tenthredinid enemies of larch on the European continent, where the genus Anoplonyx has apparently never occured in sufficiently large numbers to cause economic damage. In Britain, where larch is not a native tree, the sawflies attacking its leaves are all restricted to it and so must have been introduced into the country.

Male.—General coloration fuscous, with the vertex of the head, pectus, underside of abdomen, anal region, legs and base of antennal shaft mouse-grey. Fore-wings, above, covered with mouse-grey scales, amongst which are scattered irregular patches of fuscous-black scales, these predominating but forming no definite pattern; beneath, covered more uniformly with fuscous-black scales, except in the region between the first anal vein and the inner margin, which is covered with narrow elongate oval mouse-grey scales. Hind-wings above and beneath covered with fuscous scales, the inner margin furnished with long fuscous hairs. Cilia of both wings fuscous-black.

The following mosquitos should be added to the list given in my earlier paper on this subject (Bull. Ent. Res. 28, 1937, pp. 405—407).

1. Anopheles elutus, Edwards.

The larvae are found in the same habitats as those of A. maculipennis, but seem to show a greater preference for waters near the sea-shore. A. elutus appears to be considerably rarer in Corfu than A. maculipennis, but sufficient data are not yet to hand to settle this question.

2. Anopheles plumbeus, Stephens.

Not common. I have obtained the larvae from the rot-holes of oak, elm and white poplar, but never so far from those of olive-trees. They favour deep holes containing plenty of rotting material.

3. Aëdes (Ochlerotatus) caspius, Pallas.

The larvae are sometimes present in fresh, but more frequently in slightly brackish waters. They are often gregarious with the larvae of O. detritus, Hal., but are much less abundant than the latter.

4. Aëdes (Ochlerotatus) pulchritarsis, Rondani.

The larvae live in rot-holes of oak, elm and white poplar, and are sometimes met with in considerable numbers in the same hole. They prefer holes in which the collected water has become thick and very dark amber in colour owing to the presence of decaying wood debris.

5. Orthopodomyia pulchripalpis, Rondani.

The larvae are found in the same habitats as those of O. pulchritarsis and are often gregarious with the latter. They are less plentiful, on the whole, than O. pulchritarsis and prefer somewhat clearer water.

Note.—In my paper referred to above I mentioned that Finlaya echinus, Edw., is commoner in Corfu than F. geniculatus, Oliv. This statement is due to an error of determination arising from the fact that in many of the Corfu larvae of F. geniculatus the bristles of the abdominal tufts are somewhat more developed than those described in some text-books.

The persistence, as assessed by biological and chemical methods, of field deposits on apples from two spray programmes, each of DDT, carbaryl or azinphos-methyl, was compared throughout eight weeks following the first application in an orchard in south-eastern England. Newly emerged larvae of the codling moth, Cydia pomonella (L.), were used to assess, in the laboratory, the biological activity of the deposits. The spray programmes studied were (1) two applications of conventional concentrations (i.e., 0·1 per cent, for DDT and for carbaryl, 0·04 per cent, for azinphos-methyl) three weeks apart and (2) three applications of half these concentrations at two-weekly intervals. DDT wettable powder, carbaryl and azinphos-methyl were compared in 1961, DDT emulsion, DDT wettable powder and carbaryl in 1963. Results of biological and chemical assessment of the deposits are presented graphically. Over-all, the performance of the three-application programmes was as satisfactory as that of the two-application programmes, although a smaller amount of chemical was used. The serious reduction in deposit caused by heavy rain shortly after the first application of DDT wettable powder and of carbaryl in 1961 is noted. In the absence of heavy rain, carbaryl was biologically the most persistent, but the best performances of the other chemicals were almost as good as that of carbaryl.

LD50 values of fresh deposits obtained by field spraying were shown to be similar to those obtained by laboratory dipping.

Comparison of the toxicity of fresh and weathered field deposits of similar magnitude indicated that the biologically available proportion of a DDT deposit from either formulation decreases as a result of weathering. This phenomenon was not found to occur with carbaryl and either not at all or to a much lesser extent with azinphos-methyl.

The deposits obtained in the comparison of the spray programmes were separated into their fresh and aged components, so that differences in the contribution to the final deposit provided by each application could be seen. With the very persistent DDT emulsion, only about half of the six-week deposits was composed of chemical from the final application, but, with the much less persistent carbaryl and azinphos methyl, the six-week deposits were almost entirely derived from the final application. By substitution in an equation to obtain the rates of decay of the deposits from the three-application programmes of all chemicals, it is shown that deposits from the second and third applications were, in all cases, more persistent than those from the first. Possible reasons for this difference are discussed.

The significance, in terms of field control, of the results for the larvicidal activity of the deposits from the different spray programmes is indicated. It is concluded that data on the LD90 of insecticidal deposits on apples, together with measurement of their persistence in the field, can be used to assess the probable field performance of codling-moth insecticides and to determine the most efficient means of employing them, although the deposit level that ensures 90 per cent, larval mortality in the field is higher than the LD90 determined in the laboratory.

Vast populations of Meligethes heteropus Gerstaecker have recently been found on millet in Nigeria. The damage they cause is described and the previously unknown male is described and figured. The validity of characters previously used in the diagnosis of Meligethes is discussed.

The two isomers demeton-O and demeton-S which occur as a mixture called demeton in the commercial insecticide Systox act on Aphis fabae Scop. as contact and systemic insecticides and as fumigants.

When applied as a contact insecticide or systemically via the roots from solution or from soil, demeton-S was about ten times as toxic to Aphis fabae on broad beans as demeton-O. Using demeton-S containing 32P it was shown that, when applied to the roots, radioactive material passed to all parts of the plants and that the concentration in the aerial parts was higher than in the roots. Leaf samples were more active than stem samples. By radioassay and by the cut tap-root technique it appeared that the lethal dose of demeton-S was equivalent to about 1·0 mg./kg. of fresh plant tissue. The lethal dose of demeton-O by the cut tap-root technique was 3·0 mg./kg. From solutions, the plants first absorbed demeton-S preferentially, then water preferentially. Demeton-S was more rapidly absorbed from sand than from soil.

Both isomers were translocated from older to younger leaves of broad beans usually in sufficient quantities to kill Aphids but the results were more consistent with demeton-S. The quantity translocated downwards was small. A low light intensity before and after treatment reduced the quantity of demeton-S translocated. There was also a reduction in the quantity translocated when the plants were only shaded before treatment. One day of shading was sufficient to cause the maximum reduction.

Solutions of the two isomers gave off toxic vapours and plants treated via the roots gave off toxic vapours from the foliage.

The species commonly known in the West Indies as the pepper flower-bud moth has been shown not to be Gnorimoschema gudmannella (Wlsm.), as hitherto supposed, but an undescribed species, for which the name Gnorimoschema capsica is proposed. The species is described and differentiated from G. gudmannella and other species in the Grnorimoschemini.

Theresia (Procris) ampelophaga, Bayle, a moth of the family Anthroceridae (Zygaenidae) is one of the most important pests of the vine in various countries, but the existing accounts of its bionomics are very contradictory and not free from inaccuracies.

There are in the Sudan three species of migratory locusts : Anacridium moestum melanorhodon, Walk., or the tree locust, Locusta migratoria, L., and Schistocerca gregaria, Forsk., sometimes termed the desert locust. Of these the last-named is the plague locust of the country—the other two species being relatively unimportant—and is the species referred to as the “ locust ” throughout this paper.

From 1899 till 1917 swarms of locusts occurred annually, but then followed a period of ten years during which the Sudan suffered no damage from this pest. In 1927 and again in the succeeding year the locust reappeared as a plague, and there is little doubt but that it is to be expected year by year over an extended period and until the cycle either naturally terminates or is artificially brought to an end. The swarms of fliers appear from May onwards and oviposit in July and August when and where in the arid regions sufficient rain has fallen, the resulting generation of adults emigrating in October. A certain amount of breeding takes place during the winter on the Red Sea littoral, where winter rains occur, but this district is relatively small and easily dealt with ; the main problem is how to prevent breeding during the summer rainy season throughout the vast areas of the central and northern Sudan.

Attempts were made to find alternative, less persistent, toxicants to aldrin for use in baits against Anoplolepis longipes (Jerd.) in the Seychelles. More than twenty toxicants were tested (some in more than one formulation) for effectiveness as poisons and for repellency to ants at the concentrations used in baits. None was as effective as aldrin, but certain formulations of pirimiphos-ethyl, pirimiphos-methyl and mecarbam were promising because they gave good kill of ants in the laboratory and were of relatively low repellency and therefore acceptable in bait formulations.

A breeding-place of Glossina pallidipes Aust., in evergreen shrubs of Craibia sp. on the Kiangine river, Makueni, Kenya, was studied by means of hand-searching for puparia in conjunction with records of rainfall and temperature. A fly-patrol was also operated. The country away from the river was thorn-scrub, with Acacia and Commiphora trees predominating.

Three sites, each of 200 sq. yards, divided into 50 squares, were marked out, and two of them were searched monthly and the third quarterly.

Site “ A ” was searched nearly every month between April 1949 and June 1952, and full puparia were nearly always found. Numbers varied very widely; and it was noted that few could be found in rainy seasons during the months of November to January and April to May, though 1950 was an abnormal year. A consistently large increase in numbers was observed in February, the hottest and driest month, and a rather less marked increase towards the end of the long dry season in September and October. Large numbers of full puparia also tended to coincide with times of low average minimum temperature.

The numbers of flies caught on the fly-patrol did not appear to bear any close relation to the numbers of full puparia discovered.

Testing for efficiency of searching by means of marked puparia showed that about 40 per cent. of puparia were recovered, so that results must be taken as relative.

Recent developments of physiology have emphasised the importance of membranes, and in entomology, studies on the permeability of membranes would offer the necessary basis for investigations on the physiological action of insecticides, particularly those applied externally, as well as on the many aspects of insect physiology.