It is noteworthy that the breeding-places of different mosquitos vary with the seasons and that mosquitos are influenced in the selection of their breeding-places by such differences as those of temperature, relative humidity, cloudiness and rain, or alkalinity and food supply, and a further study of the breeding-places of Aëdes (Finlaya) notoscriptus, Skuse, has revealed some interesting details worthy of record. In this respect the importance of continuous mosquito work becomes particularly apparent, because at times the results obtained seem almost to be of a contradictory nature; but these variations are due to the diverse conditions under which mosquitos are forced to live in a country which at one time is subject to excessive rains and at another in the throes of a great drought. These factors tend to give to certain mosquitos an economic significance, and therefore we must not be surprised to find a semi-domestic species like A. notoscriptus displaying at times a tendency to become domestic; this mosquito has already taken to breeding in water-tanks in Western Australia, and fears of its doing so in Brisbane, when its present breeding-places have been largely done away with, seem justified.

Though our knowledge of this remarkable insect remains far from complete, fresh material, procured through Dr. C. F. C. Beeson, has enabled me to throw more light on its envelopment and to correct some misinterpretations in my earlier article (Bull. Ent. Res., xvii, p. 55, July 1926).

The paper is an accouunt of a year's work on the bionomics of Glossina morsitans in the Koalib Hills, Nuba Mountains Province, Sudan, a small area which lies 200 to 300 miles north of any other locality where G. morsitans occurs.

The fly is restricted at all times of the year to the hills, where it was found to breed in rock-shade, and is always closely associated with the Nuba inhabitants and their animals, even frequenting villages and their environs. The cattle, goats and sheep are resistant to trypanosomiasis, but all have been proved to be carriers of the disease.

Wild fauna is scarce in and near the area, and the fly is probably entirely dependent for food on the Nubas and their animals.

An experiment in direct control in a small group of hills is described. It was found impossible to reduce the fly beyond a very low minimum, but the method would be of use as a routine control in small hills.

Experiment with fly lime indicated that the shiny appearance of the lime deterred the majority of flies from alighting upon it.

Marked flies remained in the bush for ten to fifteen days during the rains, but eventually returned to the hills. Given a constant food supply there seems no reason why many parts of the bush, otherwise suitable, should not harbour fly during the rains and early dry season.

The author is indebted to Major R. G. Archibald, C.M.G., D.S.O., M.D., Director of Wellcome Tropical Research Laboratories, and to Mr. H. H. King, Government Entomologist, for much assistance and advice, also to the Provincial and District Officials for help in many ways.

The biology of Rhyssa persuasoria, L., and of Ibalia leucospoides, Hochenw., has already been sketched in a preliminary paper published in this Bulletin (xix, pp. 67–77, pl. iii, 1928) in collaboration with Mr. R. N. Chrystal, of the Imperial Forestry Institute. The following observations were made by the writer chiefly at the Farnham House Laboratory, during the spring and summer of 1928, and are gathered together in view of his departure from England. The work of collecting and rearing supplies of Rhyssa and Ibalia for shipment to New Zealand, for the biological control of Sirex nodilio (juvencus), has been continued on a larger scale. The present notes were made incidentally during this work and are arranged under nearly the same headings as in the previous paper, to which they are supplementary. One error needs correcting. It was stated (on p. 75) that the larch (Larix europaea, D.C.) is indigenous, though actually planted in the Oxford locality mentioned. As a matter of fact, of course, larch, though Palaearctic, is not indigenous to Britain.

Until the end of 1926 it was not known that Pseudococcus gahani, Green, occurred in South Africa. That it had not been recognised before is perhaps due mainly to the fact that very frequently it is found in association with P. maritimus, Erhorn, and was thus regarded as a form of the latter species. It may be noted here that P. capensis, Brain (Ann. Ent. Soc. Amer., v, p. 182, 1912) is a synonym of P. maritimus, Erhorn, as previously recorded in “Farming in South Africa” (i, pt. 2, p. 64, May 1926).

The cultivation of the sunflower (Helianthus annuus) in Ukraine is of great importance, especially in the eastern part, which suffers much from drought. In this area the sunflower constitutes the largest single crop, even exceeding maize, owing to its greater capability for withstanding drought.

1. The only biting fly of common occurrence in Mauritius is Stomoxys nigra.

2. The method of transmission of surra by Stomoxys nigra is direct, i.e., it occurs when flies take a meal on a surra-infected animal, with trypanosomes in the peripheral blood, and immediately afterwards feed on a healthy animal.

3. Trypanosomes are found active in the proboscis of Stomoxys from one to ten minutes after a meal, when the temperature of the room is between 25 and 27° C.

4. No active form of trypanosomes can be found in the gut, Malphigian tubes or salivary glands of the fly 24 hours or longer after a meal on an infected animal.

5. For successful transmission the interval between the feeding on the infected and on the healthy animal must not be more than ten minutes.

6. Trypanosomes in the gut of Stomoxys are active from one minute to one hour after a meal on a surra-infected animal.

7. Trypanosomes are partially disintegrated, the cytoplasm becoming more granular and the flagellum disappearing, 24 hours after an infected meal.

8. No developmental forms of trypanosomes have been found in the salivary glands, gut or Malphigian tubes of Stomoxys nigra 24 hours or more after an infected meal.

9. When trypanosomes could not be found in the peripheral blood of a surrainfected animal, transmission could not be effected.

Prior to 1900–05 South Ankole was free from tsetse.

About 1906–07 Glossina morsitans crossed the Kagera northwards at three points: Kakitumba, Nyaruambu, and Kafunza (Tanganyika). Cattle in those areas were moved north on the advent of the fly, thus spreading it in small numbers, mainly northwards.

The epizootic recorded in Ngarama and Bukanga in 1910–11 was due to “direct” transmission following the introduction of infected cattle from the south.

The influx of man in 1914–15 through the Nyaruambu and Kafunza centres, chiefly the former, caused marked disturbances and rapid spread of the fly, principally along the line of communication to the north.

The sudden withdrawal of the human element resulted in marked diminution of fly density, and the advent of rinderpest in 1919 destroyed an important alternative food supply, thus giving further impetus to the reduction.

After a period of 27 years the tsetse had retired to those two points from which it had originally spread.

The Kakitumba centre had not suffered human invasion, as did the foregoing, and no great activity of Glossina has therefore been recorded.

The picture presented is that man himself has proved the greatest factor in that wide and rapid spread of Glossina which Ankole experienced during 1907–1917.