1. In this paper five species of Simulium and 16 species of Austrosimulium are dealt with.

2. The new genus Austrosimulium differs mainly from the former in the number of joints in the antennae, which are ten instead of eleven; it seems to be restricted to the Indo-Australian region.

3. In many cases the species of Austrosimulium cannot be differentiated from each other in the adult stage, although they are perfectly different in their early stages and especially in the pupal stage.

4. Seven species of Austrosimulium occur in New Zealand: A. vexans, Mik, A. ungulatum, sp. n., A. australense, Schin., A. tillyardi, sp. n., A. longicorne, sp. n., A. multicorne, sp. n., A. laticorne, sp. n. Only the first two of these are distinguishable from the others in the adult stage; the remainder can only be differentiated in the pupal stage or the late larval stage.

5. Five out of these seven New Zealand species are known in their early stages.

6. In Australia (including Tasmania) five species of Simulium and nine of Austrosimulium are known to the writer, i.e.: S. aurantiacum, sp. n., S. fergusoni, sp. n., S. ornatipes, Skuse, S. umbratorum, sp. n., S. terebrans, sp. n., A. crassipes, sp. n., A. cornutum, sp. n., A. tasmaniense, sp. n., A. victoriae, Roub., A. furiosum, Skuse, A. bancrofti, Taylor, A. torrentium, sp. n., A. simile, sp. n., A. weindorferi, sp. n.

The two species A. victoriae, Roub., and A. furiosum, Skuse, have not been identified with certainty, so that further investigation may show that one or two of the new species are synonymous with them.

7. The early stages of one species of Simulium and five of Austrosimulium from Australia are here described.

This report contains a record of the trypanosome infections, food and breeding of G. morsitans and G. tachinoides obtained by examining the flies at various foci over a period of fourteen months.

It confirms the fact that the breeding of both species is practically confined to the dry season and follows a period of increased food supply. G. tachinoides is well fed through the rains, except in one month of flood, and starts breeding as soon as the rains cease, owing to its habit of feeding on reptiles. G. morsitans starts free breeding about six weeks later, as its increased food supply is due to the ungulates becoming more available.

G. morsitans does not feed on reptiles, but in times of hunger draws a proportion of its food from birds, the largest proportion recorded being 17 per cent, in one month at one focus. It draws the bulk of its food in this locality from small antelope, large game being scarce. G. tachinoides is much less specialised in its diet, and in the wet season nearly one-fifth of its food was drawn from a group of animals which included man, monkey and dog.

The infection of the flies with T. vivax and T. congolense bears a close relation to the amount of blood obtained from antelope, and consequently morsitans is in general nearly four times as heavily infected as tachinoides. Infections with T. brucei and T. gambiense are scarce in this locality. Trypanosome infection rises just before the main breeding season in morsitans in all localities and in tachinoides in places where the fly is largely a mammal feeder. The proportional infection in general falls in the season of most rapid breeding, owing to masking of the actual rise by the number of young flies examined. It rises rapidly when breeding ceases. The total infection is reduced when fly food is hard to obtain, in the time of long grass and flood, owing to T. vivax infections dying out when the flies are starved.

It is shown that in some cases T. grayi may be obtained by tachinoides when it feeds on Varanus, and a somewhat similar infection in the laboratory may be obtained by feeding the flies on toads.

It is shown that in some cases T. grayi may be obtained by tachinoides when it feeds on Varanus, and a somewhat similar infection in the laboratory may be obtained by feeding the flies on toads.

There is just an indication that postponement of grass burning may interfere with the free breeding of morsitans and in some cases that of tachinoides. This possibility is to be tested.

The experiment of excluding game and pig from one of the dry season foci of the flies by means of fencing will be carried out.

1. Shinyanga is divisible into:

(a) Thorn-bush country containing plenty of tsetse but no population (Pl. x, figs. 1 and 2). This now covers far more country than it did fifty years ago, owing, first, to depopulation caused by natives wars, secondly, to depopulation caused in the past fifteen years by (chiefly) the advance of tsetse; and its distribution has also changed greatly.

(b) Open grass-land, produced in the past from the thorn bush by the settlement in it of people in sufficient numbers to clear it and keep it clear through their cutting for firewood and building and the browsing of their stock (Pl. xi, fig. 2; Pl xv, fig. 1).

2. Except in one respect the position in the open country is ideal. There is complete segregation of tsetse and people, and a situation exists in consequence amounting, for practical purposes, to control of the tsetse. All the people are able to keep cattle and all the children to get milk, tsetse are excluded, sleeping-sickness is excluded, and, owing to the compactness of settlement, mammalian pests are excluded except from the margins, and the people generally are accessible for purposes of administration, medical treatment, education, and agricultural development.

3. The exception is this. The tree roots still survive in the open country and, whenever population thins for a time, shoot up into bushes and trees. Where these are adjacent to tsetse bush, the fly is carried into them, while they are still small, on persons passing to and fro, and cattle begin to die. The people then fall back, allowing new bush to spring up and the process to be repeated. In Shinyanga this retreat and the reconquest by fly has been for some time at the rate of a mile a year, and new “fronts” have been formed, so that the cattle-areas are now nearly surrounded.

4. The position is serious and urgent. If it had not been taken in hand the cattle areas were doomed, as were the present schemes of development, and the railway now planned on the strength of the presence of population might have led ultimately to a depopulated waste.

5. The remedy is in the hands of the people themselves. They have merely each year to combine to cut back the young shoots and the bush and the tsetse cannot advance. And persons must not allow the flies to travel on them into cleared areas.

6. But the retreat, and natural increase of stock, have caused congestion of the cattle in the areas still populated, with severe shortage of grazing, and deaths; and the destruction of grass has led to erosion and serious loss of soil (Pl. ix, figs. 1 and 2). The remedy is again easy. When the people come out each year to cut back the young shoots, they should take the opportunity to clear for some little distance into the bush and so get enough grazing. Also, any new agriculture likely to demand much ground, and so still further to reduce the grazing, should be located so far as possible in the fly-bush. All this was explained to the people, and they asked us to organise an effort on their part. This we did, in May and June 1924, when about ten thousand men went into camp under their respective Sultans and headmen and cleared in the most energetic manner many square miles of tsetse bush on a great part of the Shinyanga tsetse “front.” It only remains to organise this effort as a popular annual custom and to locate the clearings knowledgeably and in conformity with a thoughtout plan in order gradually to break up and destroy the fly-belt. The lessons as to management that were learned from this year's clearing are detailed on p. 331.

7. A small, typical, infested block of the fly-bush has been cut off by clearing and an experiment initiated: (a) in-inducing natives to settle in the barrier, so as to widen it automatically and keep it clear; (b) in clearing the block itself of fly; and (c) in testing the width of barrier which, combined with such precautions as may prove of use, will prevent the block from becoming reinfested from the main bush. The initial response to the inducements offered (p. 000) has been good.

8. The first step towards breaking up the fly-belt on a greater scale has been taken by clearing, to a width of 400 yards on either side, a road traversing a point (Samuye to Kizumbi) at which the fly-belt narrows to seven miles. It is planned to make (and greatly widen) further breaks and to attack in detail the blocks broken off, should it prove difficult otherwise to prevent reinfestation of country that may be cleared of fly by grass-burning, etc.

9. Felled bush continued to harbour fly for some time, at any rate if people and game continued to wander between it and the bush as yet unfelled. Complete destruction of the timber by twice piling and burning it made it uninhabitable by fly, but if time is of no account, the bush can lie till the twigs and small branches of it are warped downwards into a closer mass by the next rains and so are destroyed by the grass fires of the following year.

10. A direct prohibition, enforced by a patrolling guard here and there, reduced nearly to nothing the carrying of flies into cleared or cattle country by man. Game wandered in and out almost entirely at night. The stationing of a pair of fly-boys on a road with nets, combined ultimately with dark shelters alongside for the attraction of the flies, was most useful during an entire year in preventing the carrying in of flies by cars and wayfarers. The attachment of brown paper smeared with “rat varnish” to the hoods of cars and the backs of natives was useful in destroying flies frequenting a road.

11. Mere cutting of tsetse bush is useless, for it springs again, so that it is futile to try to gain ground by this means faster than we can consolidate it. The following measures for the consolidation of clearing are being tested now in Shinyanga: The introduction of native settlement to keep the ground clear automatically; the special cutting down once or twice a year by each village of the new shoots for a few hundred yards round; the encouragement of the keeping of goats; the diversion of large scale agriculture by ploughing, which entails stumping, to the clearings it is wished to consolidate; the digging up of stumps by the natives for firewood; and the killing of trees by poisons and particular forms of ring-barking.

12. The annual postponement of the grass fires till October, and then lighting them on an organised plan, was advocated some years ago (Bull. Ent. Res. xi, 1921, p. 382), and was encouraged by circular in Tanganyika Territory in 1921, when also I carried out a successful experiment near Kilosa (Pl. xv, figs. 1, 2). Father Cirvegna took up the organisation of the measure over a small piece of fly-belt at Madibira, in the Iringa district, and there seems to be little doubt that he has cleared the area of fly by means of it in three burnings.

A large scale experiment by myself this year in the Nzega and Shinyanga subdistricts seemed to show: (a) that by means of native guards, each with an area, and some aid from the headmen, it is perfectly possible to preserve a great piece of country nearly unburned; (b) that the late grass fire, lighted on a broad front with a good wind and followed up by the burners, produces, when the grass growth is sufficient, a “drive” of the flies on the wing; these then become congregated in enormous numbers beyond the limits of the fire and in any appreciable patches of ground which escape it; (c) that in these places, by the prompt use of nets and bird-lime, it is possible nearly to exterminate the congregated flies. The fewer these congregations the more practicable is this measure, so that the destruction of the more extensive fire-excluding thickets by hand will be a useful preliminary measure; (d) that far more numerous breeding thickets and breeding logs are destroyed by such a fire than by an earlier or ill-organised fire, and that with the expenditure of some labour in the littering with dry grass of thickets and logs unlikely to be burned otherwise all may be burned, or many may be cleared by hand; (e) that a much larger percentage of dead pupae (52 per cent. in this case) may be found afterwards in breeding places thus burned through than in those that are not burned (9 per cent.).

13. Some of these indications merely confirm results previously obtained by me in Rhodesia and Tanganyika; others need to be confirmed by means of further experimentation. Meantime, combined with Cirvegna's result, they suggest that late organised grass burning is likely to be of value over the very considerable areas in Africa in which the grass and the dry season are long and organisation is possible. But even if this should definitely prove true, means of preventing reinfestation must be studied, for these may turn out to be a serious difficulty.

14. The relations of the fly and the game are not being ignored. They are being studied and will be the subject of special experimentation and, if necessary, of special localised measures fitted into our general scheme of control.

15. This scheme amounts to an attempt to destroy and control tsetse by means of agencies and resources already in existence and merely requiring to be diverted specially to that purpose and organised, and by enlisting the co-operation of the people themselves who are to be aided and protected. This is both the most practical way of dealing with the problem and the way that best accords with the sound policy of educating the natives to understand and attack their own problems and advance themselves through their own efforts.

In the form of the head this genus is allied to the Acidia-Pseudospheniscus group, but is distinguished by the very short antennae, by the bare third vein, by the dc. bristles being placed on the line of the a. sa., by the peculiar coloration of the head, and by the wing-pattern of the Aciura type. Only one as yet undescribed species from Abyssinia, Br. kovácsi, Bezzi.

♂♀. Integument red-brown, clothed with dense scaling, which may be either nearly uniform grey, or nearly uniform sandy, or again either of these more or less heavily mottled with dark brown; the pronotum with three very faint darker stripes.

In my recent revision of the mosquitos of the Australasian region the following species were mentioned as occurring in the Solomon Islands, the specimens having been for the most part collected by Dr. A. G. Carment:

Anopheles (Myzomyia) punctulatus, Dön.

The purpose of this paper is to direct attention to the possibilites of sodium fluoride as an insecticide. Recent investigations of this salt as a stomach poison, which I have undertaken with cutworms and locusts, as well as its few but successful previously known uses as an insecticide against fowl-lice, Mallophaga on mammals, cockroaches, and earwings, indicates that sodium fluoride may, in a number of cases, replace the use of arsenical poisons. During the past decade the use of arsencial insecticides has increased rapidly. We are at present threatened with higher prices and possibly with a shortage of arsenic, a situation accentuated by the present cotton-boll weevil programme of the United States of America, which involves the use of tremendous quantities of arsenicals. Any cheap stomach poison effective against insects and promising as a substitute for arsenicals should therefore be of considerable interest to the entomologist and to the farmer, especially if it carries the additional advantage of being considerably less poisonous to man, stock and birds. Sodium fluoride meets these requirements.

Owing to a misunderstanding, certain species dealt with in the first half of this paper were mentioned as new, although they had already been described in another publication. The correct references to the original descriptions are given below, together with a few other emendations.

p. 97. Carpophthoromyia angusticeps, Bezzi, Bull. Mus. d'Hist. Nat. Paris, xxix, p. 525, 1923.

p. 103. Pardalaspis asparagi, Bezzi. This species was erroneously erected on a very small female specimen of Ceratitis capitata, W.

p. 103. Pardalaspis roubaudi, Bezzi, Bull. Mus. d'Hist. Nat. Paris, xxix, p. 527, 1923.

p. 104. Pardalaspis bipustulata, Bezzi, Bull. Mus. d'Hist. Nat. Paris, xxix, p. 528, 1923.

p. 104. Pardalaspis cyanescens, Bezzi, Bull. Mus. d'Hist. Nat. Paris, xxix, p. 529, 1923.

p. 104. For Haplolopha read Hoplolopha.

p. 111. Hoplandromyia, Bezzi, Bull. Mus. d'Hist. Nat. Paris, xxix, p. 577, 1923.

p. 115. Hermannloewia mutila, Bezzi, Bull. Mus. d'Hist. Nat. Paris, xxix, p. 580, 1923.

p. 115. Zacerata, Coquillett, Proc. Ent. Soc. Washington, xxvi, p. 64, 1924.

1. A short account of gall formation is given.

2. The stylets of Eriosoma lanigerum penetrate to within three or four cells of the cambium. Penetration is mainly intracellular, but the stylets cannot pass through the masses of sclerenchyma.

3. When a mass of sclerenchyma is encountered the stylets bend round it; if they cannot bend round it, they are usually withdrawn.

4. So far as can be seen at present, immunity cannot be explained by mechanical considerations.

5. There is strong evidence for supposing that resistance above ground is directly proportional to the percentage of sclerenchyma round the circumference of the stem.

6. The above statement must be qualified, if necessary, by a consideration of the extent to which the masses of sclerenchyma are broken up, i.e. the number of spaces that are available for the penetration of the stylets.

7. The middle lamella can be dissolved by the saliva of the Aphid; so that the check formed by a mass of sclerenchyma can eventually be overcome.

8. Variations in the character of the sclerenchyma and its position are shown to be of possible importance. There would also seem to be some connexion between the size of the Aphid and the size of the openings between the masses of sclerenchyma.

9. The relations of the stylets and stylet track to the cells of the stock are briefly summarised.

In September 1923 I was asked by Dr. C. M. Wenyon to undertake the breeding of the tick, Ornithodorus moubata, female specimens of which were sent to the Wellcome Bureau by Dr. Kelesberger from the Belgian Congo. This gave me an opportunity of carrying out a series of experimental investigations on the biology of the tick which were continued till August 1924. The results obtained from the subject of this paper

Male and female. Head mainly clothed with black flat scales, with a narrow white border to the eyes broadening laterally, sometimes a central white patch; some upright forked black scales behind. Proboscis black, as long as the front femora in the female, a little shorter in the male. Palpi black; exceeding the proboscis by the length of the apical segment in the male, not quite a quarter as long as the proboscis in the female. Antennae dark brown, pale-banded in the male; the border of the cup of the torus thickly clothed with small flat white scales, especially on the inner side.

♂. Pale greyish stramineous. Antennae clothed with short hairs, and with indefinite brownish rings. Face smooth. Fastigium of vertex cylindrical, sulcate above, with the apex rounded, and slightly inflated, viewed in profile almost truncate. Pronotum callosely rugulose; its discovery feebly saddle-shaped, with the median carina scarcely perceptible near the hind margin, which is roundly truncate; the two transverse sulci deep, the anterior one feebly bisinuate, the posterior one broadly arched; anterior margin rounded; lateral lobes sloping, somewhat longer than broad, with the anterior angle obtuse, the posterior one very obtuse and rounded, and the hind margin strongly sinuate, with a deep humeral sinus. Elytra nearly twice as long as the abdomen, with the veinlets whitish green. Prosternum armed with two not long, pointed, somewhat divergent spines. Mesosternal lobes small, rounded; metasternal lobes forming together an equilateral triangle with the angles broadly rounded. Front and middle femora armed with 0–3 small black spinules on the inner lower margin (hind legs missing in the type). Cerci (fig. 1, C) round, feebly incurved, with the apex attenuate, distinctly incurved, pointed. Subgenital plate (fig. 1, A, B) very long and narrow, slightly recurved; the lower surface almost flat, with an incomplete median ridge and two more distinct sublateral ridges running throughout the plate to the bases of the styli; the latter short, cylindrical; hind margin of the plate acutely and deeply excised between the styli.

About two months ago there was begun, under the auspices of the University of California Citrus Experiment Station, the task of monographing, as adequately as possible, the Citrus Coccidae of the world. Obviously, the scope of such an undertaking is such that an enormous amount of laborious work is required in the compilation and synthesis of scattered and partially “buried” scraps of recorded data. Even this collated information will not meet the requirements of our problem. This is particularly the case as regards geographical distribution, alternate and preferred hosts, and proper correlation of the data of distribution and damage with that of the geographical distribution and economic status of Citrus itself.

Cotton-stainers, Dysdercus spp., are most important factors affecting the growing of cotton in the West Indies and elsewhere, on account of the fact that they convey certain bacteria and the spores of various internal boll fungi which cause staining and rotting of the cotton lint.

♀. Eyes bare. Proboscis long, the stylets strongly chitinised for blood-sucking. Antennae with scanty, short hairs; the last five segments elongated. Without thoracic pits. Wings with both microtrichia and (a few) macrotrichia; a single radial cell; and the fourth vein petiolate. Legs with femora and fifth tarsal segments unarmed; tarsal segments sub-cylindrical. Claws small, equal. Empodium well developed. Spermathecae two. Male not known.

In connection with the development of cotton growing within the Empire, it has been found necessary to circulate many small batches of experimental cotton seed; and as a number of these batches pass through this country, it has been deemed advisable to disinfect them against pink bollworm (Platyedra gossypiella, Snd.) and other insect pests.

Length of body (one male), 2·3 mm.; length of wing, 1·6mm.; greatest breadth of wing, 0·5 to 0·6 mm. A large, dark brown species resembling C. nigripennis, C.I. & M.

This genus was founded to contain the single species— filicum of Maskell, which had been referred by that author to the genus Lecanopsis.

Young bolls may be shed owing to the mechanical action of stainer puncturing, apart from the introduction of any specific internal boll disease. One puncture is sufficient to obtain this effect.

Unless the carpel wall is pierced, no injury to the boll from insect attack results, and it is highly probable that the piercing of the carpel wall is essential for the introduction of internal boll disease.

Internal proliferation does not take place unless the carpel wall is pierced, and is not an essential factor in the shedding of young bolls, but rather an indication of injury from an external source.

Puncturing by stainers of the buds and flowers, before the flower petals have fallen off, may cause the shedding of the boll and the introduction of internal boll disease.

The surest superficial diagnosis of stainer injury to bolls, as compared with other insect injuries, is the finding of a bead of moisture exuding from the single minute orifice, in the case of a fresh puncture, and of a minute canal in the centre of the corked area of an injury some days old. The regularity of the rim of the corked area is a strong indication of stainer injury, the periphery of the corked area produced by the nibbling of young Lepidopterous larvae being irregular, owing to the action of the mandibles.

Visitors to Egypt during the spring tourist season frequently complain of the great abundance of fleas in this country. These insects are at this period a source of endless annoyance to all save those few fortunate individuals who, for some unknown reason, have no attraction for them.