A small belt of Glossina morsitans has been studied for four and a half consecutive years.

The community has been observed during the period of its prosperity when the population increased and attempted to colonise unsuitable country ; the outward spread of the fly was checked by insuperable natural barriers, and a period intervened when the fly advance had come to a standstill ; the tsetse were observed in their attempt to breed and establish themselves in an area that could only temporarily suffice their needs.

This optimum period was brought to a sudden close by the advent of unfavourable climatic conditions. The effort made by the community to establish a habitat in an unsuitable type of bush was frustrated by the almost complete extermination of its population. The country which had been colonised by the tsetse was depopulated, and once more was limited to a small population that had survived in the true and permanent habitats. A long period followed in which the tsetse were seen to make a slow but steady recovery. The investigation closes with recovery assured, but the community still too depleted in numbers to attempt further expansion for a considerable time.

Throughout this rise and fall in the fortunes of the fly community, the size of the tsetse population has been seen to fluctuate seasonally with the annual variations in the climate.

1. The conditions of temperature and humidity under which Xenopsylla cheopis is able to complete its metamorphosis are described.

2. The larvae and pre-pupae are easily killed by drying, but the pupae are not. The cocoon does not protect the larva from drying.

3. Development is much quicker at high than at low temperatures.

4. The rate of loss of water from the larva appears to be proportional to the saturation deficiency of the air, at any rate at 18°C., 22°C. and 29°C.—when the time which elapses between spinning the cocoon and the formation of the pupa is taken into account.

The writer is indebted to Dr. P. A. Buxton for reading and criticising the manuscript.

When studying the fauna of the soil it is obviously of the utmost importance to use such methods of collecting the animals as are thoroughly reliable and efficient, so that one can be reasonably sure of getting practically all the animals existing in a given material. It is not to be expected that one method will ensure successful collection of all the animals, because some react in one way towards the agents chiefly used, viz., strong light and heat, others react in another way. For instance, some animals, such as Tardigrades and Rhizopoda, encyst themselves when subjected to dryness and cannot be forced to move downwards away from the light and dryness as most arthropods do. As pointed out by the author (1928) all methods of mechanically separating the animals from the substratum by sieves, etc., are worthless unless applied to larger animals such as Oligochaeta, larger beetles and snails. For all smaller animals the only safe method is the automatic one based on their reactions towards light and dryness, which was devised by the late Professor A. Berlese in Florence in 1905.

This apparatus is so well known that it is not necessary to give a detailed description of it, nor need I dwell on the more or less similar apparatus constructed later, except Tullgren's, because the latter, constructed in 1917, has been used by several investigators. Tullgren substituted the funnel filled with water and heated by gas, which Berlese used for the purpose of drying the material containing the micro-arthropods to be collected, by an electric bulb suspended above the material in a cylindrical funnel at a distance of about 5 cm. above the material.

This is a third of a series of papers dealing with zoophagous gall midges of the world. The first, “ Gall Midges as Enemies of Aphids,” was published in 1929 (Bull. Ent. Res., xx, 1929, pp. 433–442) and the second, “ Gall Midges as Enemies of the Tingidae, Psyllidae, Aleyrodidae, and Coccidae,” appeared more recently (op. cit., xxi, 1930, pp. 319–329).

In this paper the species of gall midges whose larvae have been reported as preying on mites are dealt with, the first reference mentioned being in each case that of the original description or record. Practically all the literature available consists of specific descriptions and little is stated about the bionomics of the species with a few exceptions. It is a matter for regret that such scant attention has been paid to this aspect of biological control, especially in view of certain statements claiming that the larvae of various gall midges are of considerable importance in the natural control of red spider. It is with a view to stimulating further research in this direction that the present paper has been compiled.

It has been thought advisable to divide the paper somewhat arbitrarily into separate sections, dealing firstly with those species of gall midges preying on free-living mites and secondly with those species preying on gall-inhabiting mites. A further section deals with those Cecidomyids which may feed on mites. As an additional convenience, a list of plants on which the mites live is appended. The Cecidomyids which may be predacious on mites (see section 5) are not, however, included in this list.

(1) Aèdes vigilax migrates for long distances and together with Mucidus alternans disperses over considerable areas under favourable physiological conditions.

(2) Migrations are only undertaken when suitable winds make dispersal possible ; north-westerly winds distribute, under suitable atmospheric conditions, untold numbers of A. vigilax all along our foreshores.

(3) In summer the appearance in large numbers of both A. vigilax and Mucidus alternans heralds the approach of a storm.

(4) The presence of mosquitos found in wide areas in Queensland apparently devoid of water may be explained : (a) By the existence of breeding facilities in tree-cavities and similar breeding-places not visible to a casual observer ; (b) by the prevalence of suitable carrying winds by which mosquitos are blown for short or long distances from their native breeding-places ; (c) by extreme localisation of mosquitos breeding in small quantities of water mostly inaccessible to the casual observer.

1. This report continues the account of the experimental field work carried out by the Tsetse Investigation in Northern Nigeria from May 1926 up to the end of 1929. G. morsitans and G. tachinoides are the tsetse concerned. The main object of this work was to attempt to control tsetse by the destruction of primary and secondary foci by the clearing of all fringing forest, the general woodland being left untouched. Two main experimental areas have been dealt with, the Sherifuri area described previously and the Matyoro experimental area.

2. Methods of clearing and dealing with re-growth are described in detail. Records show that re-growth although very rapid the first year, then slows down to such an extent that it may not be economical to re-slash more often than every third year. The effect of clearing on tsetse was controlled by collecting fly week by week from certain fixed foci. These flies were dissected and the following factors noted : the sex proportion in the catch, the rate of catching, the state of nutrition, the proportion of very young flies, the blood content of the gut with classification of the kinds of blood found, and the trypanosome infection.

With G. morsitans, clearing of fringing forest only up to 800 yards from the collecting centre had no apparent effect on the wet season extension but at four miles it was reduced to one-sixth of its old figure.

The Solomon Islands lie to the east of New Guinea and consist of an archipelago a thousand miles in length and about half this distance in breadth. They are divided politically into the Northern Solomons (formerly German but now administered under Mandate by Australia), and the British Solomon Islands Protectorate. This latter lies roughly between five and twelve degrees south of the equator and is believed to have been united both to New Guinea and Australia from at least the Triassic to the early Tertiary. As there is now a deep sea between the archipelago and the two land-masses, the former falls into the ancient section of the continental islands of Wallace.

The rainfall averages 150 inches, the maximum shade temperature has a mean of 90°F., and the relative atmospheric humidity averages 92 per cent.

The Group consists of six large islands ranging from 60 to 120 miles in length and many smaller ones, including the isolated Santa Cruz group to the east. The main islands are composed of both coralline and volcanic (chiefly diorite) rocks and hence exhibit a wide range of soil-types from coralline sands and red clay to alluvium. Evidence of former extensive elevation is provided in raised coral-beaches. The islands are generally covered with jungle and densely wooded to their summits which rise in places to over 8,000 feet. An exception to this is the central and western portions of the northern coast of Guadalcanal, which consist of grass plains and undulating downland.

Towards the end of 1931 a study of the eggs of Anopheles mosquitos was commenced, primarily with a view to establishing any characters in the egg which may prove useful in differentiating closely allied species, and in particular those suspected of being concerned in the transmission of malaria.

The eggs of ten species of Anopheles are described and figured below : mauritianus var. ziemanni, Grünb., implexus, Theo., pharoensis, Theo., theileri var. hancocki, Edw., christyi, N. & C., gambiae, Giles (costalis, Theo.), transvaalensis, Carter, funestus, Giles, marshalli, Theo., and moucheti, Evans. Of these the writer has had the opportunity of examining specimens of Anopheles gambiae and funestus from four different regions in Uganda, namely, Kampala (3,900 ft.), Jinja (3,800 ft.), Mbale (4,000 ft.) and Fort Portal (5,100 ft.), and no local variations were observed. The eggs of two species dealt with in this paper have been previously figured by workers in other parts of the world. Edwards (1921) reproduced a drawing by Patton of the eggs of Anopheles gambiae (costalis) from Arabia, and Theodor (1924) published a drawing of those of A. pharoensis from Palestine. Both illustrations show eggs which in general structure are very similar to those of the same species in Uganda ; the sculpture of the membrane is not figured. Individual variation within the eggs of a single adult was found to be constant in the case of A. marshalli, the three forms figured being represented in each of the three batches examined.

The study of Dipterous insects in Kenya Colony has been restricted, to a large extent, to the Culicidae and their relation to malaria, and to the Tabanidae and the genus Glossina in connection with trypanosomiasis, the non-bloodsucking Diptera having received but little consideration.

“ Blowflies ” or “ maggot-flies ” are by no means uncommon in the Colony, and evidences of myiasis in its various forms are numerous. Symes & Roberts (1932) cite instances of the larvae of Sarcophaga haemorrhoidalis and of Lucilia sericata in the exposed brain substance of a woman ; and of Chrysomyia bezziana in an ulcer on the foot. Cordylobia anthropophaga, parasitic in the skin of man and other animals, is common, and Auchmeromyia luteola (in reality a blood-sucker in its larval stage) is distributed from the coast to the southern boundary of Abyssinia. The “ sheep nasal fly ” is extremely abundant, and many other larvae of Oestrus species have been recorded from game in the Colony.

Wounds, ulcers and sores in natives and in animals are often infested with maggots. I have seen, on several occasions, maggots in the ears, and in sores under the eyes, of native children, and in leg-wounds of native labourers. Still more frequently have I observed maggots in wounds of animals ; they occur at the bases of distorted, and in the scars of broken, horns, in the lesions caused by tick-bites, in injured eyes, and in the soiled fleece of sheep. Animals on the point of death are often attended by myriads of sarcophagous flies, the vast numbers of Chrysomyia marginalis in particular presenting an extraordinary sight.

This paper consists of a preliminary report on investigations of the parasites of Coleophora laricella in Europe, with a view to their possible utilisation in Canada.

Systematic and biological notes on the more important species are given.

The most promising parasite, Angitia nana, has already been shipped to Canada. It is a solitary internal parasite of the case-bearer larva. Further investigations are necessary before it can be considered safe to introduce any other species.

I am very grateful to Dr. C. Ferrière, of the Imperial Institute of Entomology, for the time and trouble he has given to the work of identifying the parasite material. The late Mr. J. C. Robbins helped materially by kindly carrying on observations while I was absent through illness, and by collecting material in the field. Mr. R. J. Spittle has been of great assistance in the production of the finished drawings, several of them being mainly his own work. A number of the earlier field collections were made by Mr. H. S. Hanson.

1. Methods used in the production of pupae of G. morsitans, Westw., in the laboratory have been described.

2. Observations, based on the pupae produced in the laboratory, have been recorded on larviposition, pupation, pupal period and stages of pupal development.

3. The pupal period was found to vary with the temperature, from 23·1 days when kept constantly at 86°F., to 48·5 days at a varying temperature, the mean noon temperature during development being 70·0°F.

4. Examination of puparia collected from natural breeding-sites showed that there is a fairly heavy mortality in the pupal stages in nature, amounting in some cases to as much as 50%.

5. Parasitisation by the Hymenopterous parasite, Syntomosphyrum glossinae, was found to a very slight degree—0·2& only.

6. Heavier parasitisation by three species of Bombyliids—Thyridanthrax abruptus, T. lineus, and T. argentifrons—occurred.

7. The living, dead, and parasitised puparia could be distinguished by (a) immersion in methylated spirit of S.G. 0·820, when those sinking would be alive, and (b) subsequent immersion in petrol of those floating in methylated spirit, when those sinking would for the greater part be parasitised and those floating would be dead.

8. The degree of temperature lethal to pupae was found to depend on duration of exposure. Thus, whereas pupae survived exposure to 55–57°C. for 2 minutes, 45–50°C. was lethal when the exposure lasted half an hour, whilst even 40°C. was lethal when continued for 4 hours or more, and pupae failed to survive 13 days at 35°C.

One of the most important pests of rain-grown cotton in the Sudan is the genus Dysdercus (Pyrrhocoridae) of the Hemiptera Heteroptera. Upon the introduction of cotton into the southern provinces of the Sudan, these insects appeared in great numbers, and in certain districts threatened to render impossible the growing of the crop. In 1926 work was started on the bionomics and control of the cotton-stainers by Cowland & Ruttledge, who were working respectively in the Nuba Mountains and the Fung provinces. Later the crop in the Nuba Mountains proving to be the more important of the two, the study of these insects was confined to that region. Mr. Ruttledge followed Mr. Cowland as entomologist in the Nuba Mountains, and the writer followed Mr. Ruttledge in 1928. The results of the preliminary investigations of Cowland & Ruttledge formed a valuable base from which the writer continued the work.

Prefatory Note.

Having had the privilege of seeing something of Mr. Chorley's very fine work against Glossina palpalis, and having had four of his traps (of the types shown in Pl. xi, figs. 1, 2, 5) in experimental use myself, I would like to state that he has, in my opinion, done particularly excellent service in evolving several good types of trap for this tsetse-fly. They have not been properly tested yet against other species of tsetse. The choice of exactly suitable sites for the traps, as with all tsetse-traps, is a matter of considerable difficulty and demands expert knowledge, but if skilfully sited, the traps catch well. They represent the acme of cheapness. The mere tacking of a skirt on a Conical Hoop Trap (1912), a Hughen's trap (1919) or a Barrel Trap (Burnett 1918) makes a “ Chorley ” Trap for tsetse-fly. A mere sack or trouserleg kept open by a hoop and with a non-return cage on the top suffices ; and the trap collapses, like a lady's dress, into no space at all. It is simply, in some of its forms (as in Pl. xi, figs. 1, 2, 5), a very slight adaptation to tsetse of Richmond's Crinoline Trap for mosquitos, published in 1927 in the Government of India's Health Bulletin, No. 11 ; in its “ ventilator ” forms (e.g., fig. 3), it is an adaptation of the Wahl & du Plessis trap for blow-flies, published in 1923 in the Journal of the Department of Agriculture of South Africa—though even here the form most used has been cylindrical.