1. The history of the occurrence of Merodon equestris in various countries is related and a list of known food-plants given.

2. The immature stages of the fly are described in detail.

3. The biology of the fly is fully discussed and additions made to our knowledge regarding it.

4. Control measures are reviewed and additional information is given, particularly with reference to the use of a poison-bait spray against the adult flies.

5. Recommendations are made as to the most satisfactory combination of methods to use for the purpose of obtaining control of the fly under field conditions.

6. A list of literature cited is given.

(1) For the first time sodium fluosilicate has been tested as a poison against the hoppers of Locusta migratoria migratorioides. This poison was found to be as effective as sodium arsenite in baits when used at the same concentration, viz., 2·44%, but was slower in its action. When guinea-corn bran is used as the carrier it is necessary to add salt to the bait as an attractant; the reason for this is not known, fluosilicate baits containing sawdust, chopped hay and chaff from cereal crops respectively were effective without salt being added.

(2) From an examination of the results of experimental work on the relative toxicities of sodium fluosilicate and arsenical compounds to domesticated animals in various parts of the world, it is concluded that the former is less toxic to stock, but that the increased degree of safety acquired through the use of sodium fluosilicate is not so great as is popularly supposed. A definite advantage of baits containing fluosilicate is that they are repellent to many animals, whereas baits containing sodium arsenite are attractive to stock.

A summary is given of the results obtained from the collection of large numbers of the puparia of G. tachinoides and G. morsitans in the Gadau-Sherifuri area and the breeding of tsetse and parasites therefrom. Totals of 106,047 puparia of G. tachinoides and 17,346 of G. morsitans have been dealt with during the two breeding seasons of 1930–31. It is concluded that the Bombyliid, Thyridanthrax argentifrons, Aust., is in this area the only naturally occurring pupal parasite of Glossina of any importance. This fly has formed as much as 6 per cent. of total emergences from G. tachinoides puparia in the month of March, and 2 per cent. of total emergences from G. morsitans puparia for the month of April.

Blow-flies and house-flies (grouped in the Dipterous family MUSCIDAE in the older sense, including CALLIPHORIDAE) are outstandingly abundant throughout New Zealand. The influence of these insects upon the health of man and domestic animals is well known. Though this work deals with the MUSCIDAE as a whole under local conditions, its main object is to record investigations upon the blow-flies with special reference to the depredations of their maggots upon New Zealand sheep.

1. An analysis of rice-field and canal waters was made over a period of 1 year.

2. The incidence of Anopheles tarsimaculatus in these fields and canals was noted.

3. The chemical factors estimated were pH, carbon dioxide, organic nitrogen, dissolved oxygen, nitrites, nitrates, phosphates and ammonia nitrogen.

4. No correlation was found between the incidence of A. tarsimaculatus and the following factors: pH, carbon dioxide, organic nitrogen, dissolved oxygen, nitrites, nitrates and phosphates.

5. In nature the female A. tarsimaculatus seemed to prefer waters with a low ammonia nitrogen content, larvae being rarely found in water with a content greater than 0·04 parts per 100,000. In the laboratory the larvae of A. tarsimaculatus lived several days in waters with an ammonia nitrogen content as high as 0·12 parts per 100,000. Therefore it was concluded that ammonia nitrogen had some bearing upon the prevalence of this Anopheles, affecting the oviposition of the female rather than the growth of the larvae.

1. Primary fly-belts round Makongo consisted of three different vegetational communities: a Cynometra-Vitex association along the main length of the Makongo river, on a clay soil; a Ficus congensis association along the river close to the town, on a sandy soil; and Isoberlinia doka woodland on moist sandy soil north-west and south of Makongo.

2. Secondary fly-belts of less dense vegetation occur in the orchard bush savannah round Makongo, and these are not colonised until the commencement of the rainy season.

3. Glossina tachinoides and G. palpalis both occurred in the riverside communities, and G. palpalis alone in the Isoberlinia woodland.

4. Along the river G. palpalis outnumbered G. tachinoides by 3:1 in the dry season. At the commencement of the rains G. tachinoides increased more quickly than G. palpalis, bringing their numbers very nearly equal, but at the end of the rains there was a decrease in G. tachinoides which restored the original proportion.

5. G. morsitans had been found at Makongo formerly but was not met with at the time of this investigation, its absence being due to the disappearance of the larger antelope from the neighbourhood.

6. Smaller game animals, small mammals and reptiles afforded an adequate food supply for tsetse in the fly-belts, and also passing herds of cattle, as well as natives from the village and travellers.

7. The distribution of G. palpalis within the fly-belts was markedly influenced by the proximity of a cattle road along which herds of cattle passed almost daily, and by village water-holes.

8. During the dry season the primary foci were always found to be the places of greatest relative humidity, and the fly does not tend to move out of these until the general atmospheric humidity has reached a certain fairly high degree.

9. In clearing the fly-belts the removal of all primary foci within a quarter of a mile of the town and of thick bush within 100 yards of water-holes was undertaken. The work lasted from the beginning of February to the end of March 1931.

10. The effect of clearing the Isoberlinia doka woodland was to banish G. palpalis completely, and it never returned to these clearings.

11. On clearing the riverside Ficus congensis fly-belt, G. tachinoides was practically eliminated for the first three months, but reappeared in the clearings in June when there was a general increase and up-stream migration of this fly. G. palpalis remained in this clearing in fluctuating numbers up to June, when observations were suspended.

12. 565 marked tsetse were liberated in the fly-belts immediately previous to clearing. Of G. palpalis 12·7% were recaptured in the clearings and 11% outside the clearings. Of G. tachinoides 5·5% were recaptured in the clearings and 6·8% outside.

1. Ecological studies on aphides attacking potatoes were commenced in 1928 with a view to elucidating certain problems of entomological interest and also the role of these insects as vectors of disease. The species include, Myzus persicae, Sulz., Macrosiphum gei, Koch, and Myzus pseudosolani, Theo.

2. The present study is confined mainly to the infestation of aphides on potatoes at a selected centre which is described.

3. Solitary apterous viviparous females were in a majority on potatoes during the period of initial infestation in early June. Their presence is explained by (1) the overwintering of aphides on weeds and field plants, (2) the first few alatae depositing single nymphs and then migrating, (3) infection from infested seed.

4. The maximum infestation was reached during mid-July, when 86 per cent. of the leaves were infested and there was an average of 2·8 aphides to a leaf. The infestation was below that of the previous three years. Macrosiphum gei bred up rapidly, at first on the flower-heads, and was the predominant species, its decline in numbers being equally rapid. Myzus persicae increased more slowly and did not reach such numbers, but the maximum was maintained longer and the disappearance of the species was delayed. Myzus pseudosolani was only taken in August and then in small numbers.

5. An estimate of the intensity of the aphis population is attempted, and in the present moderate infestation of 2·8 aphides to a leaf it was of the order of 2,000,000 aphides to an acre of potatoes.

6. A technique was established to ascertain the movement of aphides within the crop. Weekly records on observational leaves revealed that 100 per cent. of the aphides moved their site and at least 84 per cent. of each species moved from leaf to leaf within the weekly period. Daily records during the period of maximum infestation showed that 84 per cent. of Macrosiphum gei and 73 per cent. of Myzus persicae changed site within 24 hours, and of these at least 50 per cent. moved from the leaves upon which they had been observed.

7. It was noted that no attempt was made to maintain large local colonies, for the movement of both adults and nymphs was frequent, and observed colonies soon dispersed. The extended infestation of Myzus persicae is discussed with reference to its establishment on field plants, other than potatoes, during the autumn and winter.

While on a recent visit to Victoria and South Australia, I made an attempt to collect long series of Calliphoras belonging to the subgenera Neopollenia and Proekon; a special visit was made for this purpose to Seaford and to Western Port, Victoria, the type localities of C. hilli, Patton, and C. rufipes, Macquart, respectively. The collections made represent at least seven species of Neopollenia and two of Proekon.

In the autumn of 1931 I received for determination from Dr. R. B. Jackson a small number of Culicine larvae collected in Hong Kong. These included two specimens of a Uranotaenia with very remarkable antennae, which seem well worth describing as a further example of the striking and unexpected deviations of structure which occur in various members of this genus. As the specimens sent were whole larvae and not skins, the identity of the species is somewhat uncertain, but an adult of U. testacea, Theo., was obtained by Dr. Jackson at the same time as the larvae, and it is most probable that the larvae belong to that species. Incidentally, U. testacea has not been recorded from Hong Kong before.

A procedure is described which makes it possible to differentiate nuUiparous from multiparous A. elutus and hence newly hatched from old mosquitos.