The reasons for adopting the name “ leaf-curl ” for the virus disease which is manifested by symptoms of “ leaf-crinkle ” on certain varieties of cotton, and by “ mosaic ” on certain others, are discussed.

A brief review is given of the very few references in previous literature which are relevant to leaf-curl.

Up to the end of February 1931, 168 straightforward attempts had been made to transmit crinkle from Sakel cotton to Sakel by means of white-flies (Bemisia gossypiperda, Misra & Lamba), of which no fewer than 157 were successful. No transmission was obtained with any other insects.

A single white-fly can transmit the disease to a healthy plant, though infection is less regularly obtained when one or only a few white-flies are used.

There is a large amount of negative evidence which indicates that the virus is not transmitted through the seed of Sakel cotton. There is also no evidence that it can be transmitted through the soil.

In nearly 200 controlled experiments, the incubation period of the virus in the plant varied from 8 to 34 days, but over two-thirds of the recorded periods were between 11 and 19 days. Possible causes of the variation in the incubation period are discussed.

Little is known with certainty about the factors which influence the severity of the disease.

At least one case of complete recovery from the disease appears to have been observed. Partial recovery is not infrequent.

The present paper attempts to summarise the information collected by the Imperial Institute of Entomology on the swarming of migratorioides in Africa.

It is concluded that the outbreaks in West, Central and East Africa are all interrelated and probably originated in one or at most two permanent breeding-grounds.

The area most suspected is the lake district of the middle Niger, where conditions seem suitable for the formation of the swarming phase. Lake Chad is probably a secondary rather than a permanent breeding-ground.

It is indicated that the key to the problem of the cause of the original outbreak may be found in the study of recent variations in the water régime of the River Niger.

Should these suppositions be substantiated, we are well on the way towards a solution of the problem. The ultimate control of the locusts depends not on control during the swarming periods, but upon preventing the swarming phase from developing in the permanent breeding-grounds.

It is therefore important to check and augment the records of the early swarms in West Africa and more important still, to study the behaviour of the locust, its ecology, and the water régime in the suspected areas.

In conclusion the author wishes to acknowledge the constant help and advice of Mr. B. P. Uvarov. His thanks are also due to Mr. H. B. Johnston for his permission to make use of his paper in manuscript.

The pseudopupa and last larval instar of Epicauta erythrocephala, Pall., have remained undescribed up to the present, although the economic importance of the insect is very great, the beetle being an important pest of many cultivated plants and its larva a parasite of locust egg-pods. These stages are, however, figured in the work of I. Portchinsky, published in 1914, but in the figure of the pseudopupa the stigmata on the three thoracic segments are omitted.

During investigations made in early spring (1926–1927) in the environment of Old Bukhara, I found a great quantity of the pseudopupae and larvae of the last instar of E. erythrocephala in the soil. In the early spring of 1929 the same instars were reared in the insectary of the Agricultural Experimental Station at Shirabudin (Old Bukhara).

In a recent paper by the writer (Bull. Ent. Res., xxi, 1930, pp. 201–256) it was shown that the apparent fly density varied according to season. It has now been found that these seasonal variations in the fly density can be correlated with the evaporation rate.

The accompanying graph shows the mean monthly evaporation rate, and the mean monthly apparent fly density. The evaporation rate figures have been obtained from a Livingston atmometer at the Kikori Entomological Station. The fly figures have been taken from the North-East Kikori Round, because this fly-round is not subjected to large game movements and hence is considered to be the best for demonstrating the correlation between fly density and season.

The graph deals with a period of eighteen months, and it is clear that a relationship does exist between the two curves.

In June and July 1929, the fly density was at its maximum. Hence it is reasonable to postulate that, at this time, the evaporation rate was suited to the requirements of the fly community.

The following brief contribution summarises a part of the contents of an extensive Russian report on parasites of the egg-pods of some Turkestan Acridodea, studied by the writer while on the staff of the Middle-Asian Institute of Plant Protection (Tashkent, U.S.S.R.), in the years 1927–30.

The writer is specially indebted to Mr. V. I. Plotnikov, Director of the Institute, under whose supervision the work was done, and who kindly identified the Acridian hosts ; and for the identification of the parasites reared, to Messrs. A. A. Ogloblin, Santa-Anna (Scelionidae), S. J. Paramonov, Kiev (Bombyliidae), B. B. Rohdendorf, Leningrad (Tachinidae) and B. S. Kuzin, Moscow (Meloidae). The author's thanks are due also to Mr. B. P. Uvarov, for his kind assistance in the publication of this note.

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.

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.

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.

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.

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.