The following notes are the result of investigations carried out at Barberton, in the Eastern Transvaal.

In response to the expressed desire of Mr. Arthur Gibson, Dominion Entomologist, to introduce European parasites to aid in controlling the Western Wheat-stem Sawfly, Cephus cinctus, a shipment of 15,000 wheat stubs containing parasitised Cephus pygmaeus was forwarded to Canada from the Farnham House Laboratory, Farnham Royal, Bucks, England, in the early spring of 1930. This stubble was received at the Dominion Parasite Laboratory, Belleville, Ontario, and was there held in cold storage until reshipped to Western Canada, where the parasite, Collyria calcitrator, was to be liberated.

Many of the Aëdes larvae commonly met with in Nigeria have been described by Ingram & Macfie, who have made extensive studies on the Gold Coast. Wesché described larvae of seven species of Aëdes that he studied in Lagos in 1910. In 1912 Edwards published keys to the then known larvae of the African Culicinae, but many of the species of Aëdes that are plentiful in this area are not included in Edwards' key. Therefore it was thought that an additional comparative study would be of value.

The larvae dealt with in this paper by no means represent all the species that can be found in this area. They merely include the commoner ones in the vicinities of Kano, Ibadan, and Lagos, and some additional specimens of species found in Nigeria, which were lent by Mr. F. W. Edwards, of the British Museum, and Dr. V. B. Wigglesworth, of the London School of Hygiene and Tropical Medicine.

Glypta leucotretae, sp. n.

♀♂ Dark red ; head and antennae (except as follows), pro- and mesosternum to a greater or less extent, hind legs entirely (except as follows), apical third or fourth of the 4th tergite, the succeeding tergites, and the ovipositor sheaths, black ; apical joint of the scape, the extreme base and extreme apex of the hind femora, the extreme bases of the hind tarsal joints, and the hind tibial spurs, reddened ; the four anterior legs (except as follows), and the palpi, more or less red testaceous ; the clypeus, mandibles (except the teeth), scape below (in one ♂ specimen), the coxae and trochanters of the four anterior legs, a large elongate spot occupying the basal half of the dorsal surface of the hind coxae, the pronotum, the propleurae narrowly along their upper margin, and the wing-insertions of the fore-wings (but not the tegulae), white ; the ventrites and the ovipositor very pale ; stigma and wing-veins uniformly opaque brown.

The present paper deals with a further nine species of Diaspinae which are new to science. I desire to express here my sincere thanks to Mr. E. E. Green for his invaluable assistance in working out my material.

The locust infestation in Nigeria, from December 1929 to April 1931, is studied in relation to the climate and the following preliminary conclusions are made.

1. Humidity, precipitation and wind are the relevant climatic elements. Temperature does not seem of importance.

2. It is considered that the area of dispersal is limited by the humidity factor. With very few exceptions swarms remain where the mean relative humidity (9 a.m., L.M.T.) is not more than 85 per cent. and not less than 40 per cent., while most swarms are found where the humidity is from 60 per cent. to 80 per cent.

3. This humidity belt is similar to the area covered by three main types of vegetation and the swarms move across the belt according to the humidity changes.

4. Movement along the belt is largely caused by the prevailing wind.

5. Breeding does not commence after the dry season until the humidity rises to 60 per cent. and the degree of wetness, calculated from the monthly rainfall, reaches 2. Breeding does not occur if the humidity is above 80 per cent.

6. Through the dry season the adults seem unable to live much more than 22 weeks, and if optimum breeding conditions are not reached within that period death may occur.

7. Breeding towards the end of the rainy season follows some 11 to 15 weeks after the locusts become adult, so long as the humidity is not more than 80 per cent., and high humidity may cause a diapause.

8. Suitable local conditions during the dry season may allow a third breeding season.

These conclusions may be utilised in the following ways :—

1. To delimit the total area likely to be infested.

2. To forecast when the different zones will be infested by flying swarms.

3. To forecast whether and when breeding is likely to occur in each locality.

4. To check whether unidentified swarms were of this species of locust.

5. To test the possibility of one suspected breeding ground having been infested from another.

Rhaconotus mahensis, sp. n.

♀♂. Black ; scape and all legs red testaceous ; ovipositor bright red ; flagellum red-brown, possibly rather darker at apex ; wings hyaline, the setae with a distinctly fulvous tinge, and the stigma hyaline (at least not darkened).

♀♂. The integument is not coriaceous throughout, and is only sparsely clothed with setae (except on the flagellum and possibly the legs). Head smooth and highly shining, not coriaceous, impunctate, the vertex and occiput almost entirely devoid of setae ; antennae longer than head, thorax, and abdomen together ; flagellar joints in ♀ 29–33, in ♂ 26–28. Thorax : mesonotum dully shining, coriaceous ; the notauli well marked, joining slightly before reaching the posterior margin of the mesonotum ; propodeon with five longitudinal carinae, one in the middle and two on each side, these latter rather more closely placed to each other than to the median carina ; this median carina is discernible as such only in the basal half of the propodeon, thereafter becoming lost amongst the reticulate wrinkles with which the apical half of the propodeon abounds ; the lateral carinae, on the other hand, are discernible more or less throughout their length, particularly the inner pair which can generally be traced to the median apex of the propodeon where they join each other ; the integument of the basal half of the propodeon coriaceous on each side of the median carina as far as the first lateral carina, thereafter wrinkled as in the apical half.

One of the most remarkable features of the locust season during the summer and autumn of 1930 in the Sudan was the unexpected and widespread occurrence of Locusta migratorioides, R. & F. Swarms, which laid eggs over a large extent of the country, entered from the west and south-west during July and August. There is no evidence of any of these swarms having been produced within the Sudan, and the place of origin of all the early swarms was without doubt situated outside its boundaries. There is evidence that breeding continued later in the southern portions of the country, particularly in the upper reaches of the White Nile (N. Lat. 5°), and movements of swarms were reported during the winter, but no reliable observations were made on the nature or extent of these activities. Only one brood was produced in the northern and central Sudan (probably north of N. Lat. 11°), and by October all locusts bred in these parts had either migrated away in swarms or had scattered. Migration took place in the case of the gregarious phase produced by large bands of hoppers. Where, however, bands of hoppers had been broken up by poisoning, or in cases where the bands were very small, the adults did not migrate. The absence of further breeding in the northern Sudan must be connected with the absence of winter rains and suitable vegetation.

The writer was engaged on control measures against hopper bands of the Migratory Locust, Locusta migratorioides, R. & F., along the western (Nigerian) shore of Lake Chad from the middle of August to the end of October 1930.

Like Mauritius, many other cane-growing countries in the world are suffering severely from the ravages of Lamellicorn beetle grubs. In some of these countries, such as Australia, India, South America and the West Indian Islands, these insects are indigenous, whilst in others, such as Hawaii and Mauritius, some of them have been accidentally introduced.

Through intensive cultivation of sugar-cane, which in some places is the staple industry, these so-called white grubs have found an abundance of food and an adequate environment, so that they have become, even in their country of origin, a major pest of sugar-cane ; whilst in places where they have been introduced, the damage done, in some cases, is a serious menace to the sugar industry.

Heavy annual losses are being sustained in the Philippines, Queensland and Porto Rico ; at present the damage in Porto Rico is estimated to be 3 million dollars yearly.

In order to cope with such a state of affairs, all possible effort is nowadays being made in most of these countries to try to control the pests by rational and scientific methods. Though many important points have been solved by research workers engaged thereon, there still remain many unknown factors upon which enlightenment is required.

Aedophronus echinatus, sp. n. (Pl. xxi, fig. 2).

Derm black, with dense brown scaling, usually with an indefinite mottling of darker and paler scales ; the inflexed margins of the elytra fuscous.

Head not very convex, with the median stria extending to the vertex and the anterior transverse stria slightly curved ; the infra-ocular margin much narrower than the base of the scape and not projecting ; the setae short, stout and curved backwards ; the eyes comparatively large, highest much behind the middle, and with the hind margin devoid of scaling. Rostrum longer than the head (5·5 : 4), much shorter than its basal width (5·5 : 7·5), narrowed in front, straight at the sides, with a shallow impression on the apical half and with no median carina ; the marginal carina of the epistome obtuse but distinct. Prothorax transverse (3·5 : 6), strongly rounded at the sides, widest at the middle, subtruncate at the apex, which is only slightly narrower than the base ; the dorsum with an abbreviated median stria on the basal half and bearing on the disk short curved setae like those on the head, the lateral ones much longer, stout, straight and pointed (when unbroken), the longest being about as long as the scape.

In 1927 the writer published a paper entitled “ Notes on the food-plants and habits of some Southern Nigerian Insects,” compiled from observations made between 1922 and 1925 ; the present paper contains additional data obtained since 1925.

During work on mosquitos in Uganda a certain number of hitherto undescribed larvae have been found ; advantage has also been taken of the opportunity to redescribe from fresh material some species of which the published descriptions are (in the light of our increased knowledge of mosquito larvae) found to be inadequate.

Unless otherwise stated all larvae are from the neighbourhood of Kampala. All descriptions are of fourth-stage larvae, and in every case identification of larvae has been made by comparison with the cast skins of isolated specimens from which adults have been bred. The nomenclature used for the head-setae is that proposed by Edwards & Given ; measurements of the head are always maxima. As the setae of the thorax and abdomen do not appear usually to be of much value for purposes of specific identification descriptions of them have in most cases been omitted.

For determination of adults and other assistance the writer is greatly indebted to Mr. F. W. Edwards, of the British Museum.

Adult insects belonging to the genus Hypoderma, all species of which in their larval stages are parasitic in Ungulates, fall naturally into two groups. In the first of these, represented by Hypoderma bovis, De G., H. lineatum, Vill., and H. diana, Br., the body is conspicuously hairy, and the dorsum of the main portion of the thorax (scutum) is marked with a series of shining black, raised stripes or longitudinal wheals. In the second group, to which belong H. silenus, Br., H. crossi, Patton, H. corinnae, Crivelli, and doubtless also H. aegagri, Br., the hairy covering of the body is sparser and less noticeable, and the dorsum of the thorax is devoid of the markings just mentioned. The species to be described below forms an addition to the second group.

In order to investigate the possible means of controlling introduced plant pests, the course that has been considered advisable to follow has been that of a general biological survey of the particular species under its native conditions and, so far as is possible, a comparison between this and a similar survey in the country to which it has become introduced. Such a survey should include the following aspects :—

Germination of seed : Normal percentage germination, germination of fresh and old seed, dormancy, “ hard ” seed, effect of varying external conditions or previous treatment upon germination of hard seed (if present). Seed reserves in soil ; continuous or discontinuous germination.

Establishment of seedlings : Effect of grass, leaf debris, bare soil, etc. ; root development ; causes of mortality.

Flowering : Periods of flowering, number of flowers ; mode of pollination.

Seeds and dispersal : Number of seeds, manner of dispersal, mortality before germination.

Relation to plant communities.

Relation to climate and soil types.

Geographical distribution.

Relation to insects : Insects found on the plant at different seasons ; nature and extent of damage to vegetative parts, flowers and fruits.

It is a matter of general agreement that atmospheric humidity is often of great importance in limiting the times or places at which insects are abundant. But though one may collect facts which suggest that a particular degree of dryness or dampness favours some stage of an insect, it is not easy to devise experiments which will give unassailable facts. Some of us feel that the precise study of water relations and water balance may lead to greatly increased knowledge of the living insect, and therefore to results of economic value ; and it is certain that a fuller understanding of these matters is delayed because few know the methods appropriate for measuring and controlling humidity.

The purpose of the present paper is to make known a number of practical methods, which might be of service to a worker even in a remote country. As this is my objective, I shall include material which is already well known to physicists, and as our concern is with the conditions in the places where insects are actually living, I have given particular attention to unorthodox devices which can be used in small spaces and which are portable; among the great variety of methods, I have endeavoured to show what is good and bad in each.

Puri has divided the Indian Anopheline larvae into two divisions and four groups according to the character of the pleural hairs. The following is a study of the larvae of some South African Anophelines on the same lines.

The sandflies of the two largest Italian foci of visceral leishmaniasis, Naples and Catania, were studied.

The following species were found : P. papatasii, P. perniciosus, P. sergenti, P. vesuvianus, sp. n., P. parroti var. italicus var. n.

P. papatasii and P. perniciosus are the commonest sandflies in the areas examined.

Out of 1,547 ♀♀ dissected none showed a natural infection with Leishmania.

P. papatasii was infected with Italian strains of L. infantum by feeding on cultures through membranes. The infection rate was low, but in contrast to Indian strains of L. donovani in the same sandfly, the infection once established did not die out.