The author desires to express his sincerest thanks to the authorities of the Zoological and Geological Survey of India and of the Asiatic Society of Bengal for allowing him to consult the necessary literature in their respective libraries, and to the members of the Lac Association Committee and Mrs. D. Norris, the Director of the Institute, for their generous help. He is also much indebted to Mr. W. B. R. Laidlaw, the Entomologist, for going through the manuscript, and to the artist, Mr. E. Heber, for the illustrations accompanying the paper.

The factors responsible for the biological control of insect pests fall into three main groups. The first group includes the micro-organisms (Protozoa, Bacteria, and Fungi) producing what is ordinarily called disease; the second comprises the entomophagous insects which lead, during part or all of their life-history (generally during the larval stage only) a parasitic existence, while the third contains a great assemblage of animals of various kinds which agree in being carnivorous in habit and are known as predators. It is difficult to formulate definitions of parasite and predator which are applicable to all cases. The most satisfactory general distinction is perhaps the one recently suggested by E. Rabaud (1928), who restricts the term “parasite” to species which remain permanently attached to a living host, and considers as predators all species which come into contact with the host organism only at feeding time. Each of these categories can be subdivided, according to the effect the parasite or predator exerts upon its host, into sublethal or benignant and lethal or malignant species. Few, if any, of the parasitic entomophagous insects are of the sublethal type, the species whose habits correspond most closely to the definition being perhaps the bee-louse (Braula coeca, Nitzsch), which, however, is rather a commensal than a parasite. A few parasitic insects, such as some of the dipterous parasites of Orthoptera and Dermaptera (Thrixion halidayanum, Rond., on Leptynia hispanica, Bol.— v. Pant el 1897; Rhacodineura antiqua, Meig. on Forficula auricularia, L.—v. Thompson 1928) do not actually kill their host before issuing, but it dies usually within a relatively short time. In the majority of cases the host is destroyed before the parasite has completed its larval development. Benignant predacious entomophaga are also uncommon among the Arthropods. Certain Chironomids, Simuliids and even Culicids suck the blood of caterpillars, adult dragonflies, moths and butterflies, and other insects, without necessarily killing them (v. Edwards 1923) ; but, in general, the entomophagous insect and Arachnid predators, being as large as or larger than their hosts, cause death, as do the vertebrate predators.

The Rutherglen bug is a well-known pest of fruit trees, vines and other crops in Australia, and has been recorded from every State in the Commonwealth, even Western Australia not being free from it.

The identity of this insect has been uncertain for some time past, although it has been assumed in economic literature that the species described by Bergroth in 1891 as Nystus vinitor is identical with the Rutherglen bug, since it is the only representative of the genus Nysius to have been described from Australia.

In 1927 Mr. R. Veitch, Chief Entomologist of the Department of Agriculture and Stock, Brisbane, sent a collection of Nysius spp. to the Imperial Bureau of Entomology for determination. They were handed over to Mr. W. E. China, of the British Museum, to whom I am indebted for the very considerable assistance given me in the preparation of this paper.

The collection, which consisted of a number of insects off different plants and from various localities, contained two distinct species, one of which agreed with Bergroth's very inadequate description of N. vinitor (I have not seen the type) ; the other turns out to be a new species, which I propose to name Nysius clevelandensis, since all the locality labels of this insect were marked Cleveland.

Caterpillars of the moth Holcocera pulverea, Meyr., along with those of Eublemma amabilis, Moore, do great damage to lac cultivation by feeding upon the living insects. Misra* and Imms & Chatterjee† have pointed out that H. pulverea may be found in even greater numbers than E. amabilis, though the predacious nature of the latter is more generally recognised. I have been able to confirm this observation with North Indian species of lac insects growing on Butea frondosa and Schleichera trijuga. However, in South India the wild species of lac, Lakshadia communis, at least in Mysore, is entirely free from the attack of H. pulverea, while Lakshadia mysorensis, the species commercially cultivated on Shorea talura, is never attacked by H. pulverea to the same extent that it is by Eublemma amabilis. With L. mysorensis this is partly due to H. pulverea being heavily parasitised. In the pupal stage this moth is attacked by the Chalcid, Eurytoma pallidiscapus, Cam. Imms & Chatterjee mention that only four examples of this parasite were reared by them during the entire course of their study, indicating its rare association with North Indian species of lac insects. In Mysore it is far from being scarce, which has enabled its life-history to be traced as a pupal parasite of H. pulverea. Fig. 1, a, shows a pupa of this moth from which a female, Eurytoma pallidiscapus, was reared on 14th November 1922.

During the summers of 1927 and 1928, the rearing of the Braconid, Alysia manducator, Panz. (Bull. Ent. Res., xvii, pp. 219–229) for shipment to Australasia as a measure against the sheep-maggot, was continued on a large scale at the laboratory of the Imperial Bureau of Entomology, Farnham Royal, Bucks. In addition a study was made of the Anthomyiid, Hydrotaea dentipes, Fabr., as a possible natural enemy for the buffalo-fly, Lyperosia exigua, de Meij., which has become a serious pest of cattle and buffalos in Northern Australia. Owing to the cold and wet conditions prevailing in 1927, the results were very irregular; but certain general facts regarding the complex of necrophagous maggots, predacious maggots and their respective parasites, gathered during this work, seem worth recording.

While measuring the separate parts of the head in larvae of Anopheles maculi-pennis in the summer of 1926, I observed that in the later stages of the development in each phase the posterior part of the head is in the form of a collar, the length of which increases up to the next moult, whereas the anterior part of the head remains unchanged.

The identification of mosquito larvae, especially of the genus Anopheles, is now so common a practice in the Tropics that the need of a simpler method of mounting has been widely felt. Whereas in many instances a larva can be identified by examining it alive in a drop of water, in countries where many similar forms are met with mistakes are sometimes made. A great deal of identification work is doneby Health Inspectors who have not the practice necessary for determining species while they are alive, and in Malaya, where some species cannot be separated by an examination of the anterior clypeal hairs alone, a quick method of mounting so that occipital hairs and other structures can be seen is required.

In his recently published work, “A Classification of the Higher Groups and Genera of the Coccid Family Margarodidae” (U.S. Dept.Agr., Tech. Bull. no. 52, July 1928), Mr. H. Morrison has made some sweeping alterationsin the previously accepted status of tribes and genera, some of which may possibly be open to criticism. But his classification is so vastly superior to anything hitherto attempted that—if only for the sake of uniformity—it should be adopted until a still better complete classification has been propounded. So far as it affects the matter dealt with in the following paper the only novelty is the erection of a new subfamily, Coelostomidiinae, with several new tribes and genera, to accommodate the species hitherto included in Coelostomidia, together with several allied genera.

♂ ♀. Derm black, with dense mosaic-like sandy-brown scaling variegated with grey and blackish scales; the pronotum usually with an indefinite pale median stripe; a greenish grey patch on each side of the prosternum.

Amongst a number of larvae collected in the Yokeskei River, about twelve miles from Johannesburg, on 31.v.1928, two were found which appeared to be new. These subsequently pupated and finally hatched, one on 15.vi.1928 and the other on 18.vi. 1928. The adults were seen to be Anopheles argenteolobatus, Gough. Repeated collecting after this has failed to reveal further specimens. Larvae of the following mosquitos were found in the same pool: Anopheles squamosus, A. cinereus, A. rufipes, Culex salisburiensis, and C. theileri.

It is noteworthy that the breeding-places of different mosquitos vary with the seasons and that mosquitos are influenced in the selection of their breeding-places by such differences as those of temperature, relative humidity, cloudiness and rain, or alkalinity and food supply, and a further study of the breeding-places of Aëdes (Finlaya) notoscriptus, Skuse, has revealed some interesting details worthy of record. In this respect the importance of continuous mosquito work becomes particularly apparent, because at times the results obtained seem almost to be of a contradictory nature; but these variations are due to the diverse conditions under which mosquitos are forced to live in a country which at one time is subject to excessive rains and at another in the throes of a great drought. These factors tend to give to certain mosquitos an economic significance, and therefore we must not be surprised to find a semi-domestic species like A. notoscriptus displaying at times a tendency to become domestic; this mosquito has already taken to breeding in water-tanks in Western Australia, and fears of its doing so in Brisbane, when its present breeding-places have been largely done away with, seem justified.

The cultivation of the sunflower (Helianthus annuus) in Ukraine is of great importance, especially in the eastern part, which suffers much from drought. In this area the sunflower constitutes the largest single crop, even exceeding maize, owing to its greater capability for withstanding drought.

Prior to 1900–05 South Ankole was free from tsetse.

About 1906–07 Glossina morsitans crossed the Kagera northwards at three points: Kakitumba, Nyaruambu, and Kafunza (Tanganyika). Cattle in those areas were moved north on the advent of the fly, thus spreading it in small numbers, mainly northwards.

The epizootic recorded in Ngarama and Bukanga in 1910–11 was due to “direct” transmission following the introduction of infected cattle from the south.

The influx of man in 1914–15 through the Nyaruambu and Kafunza centres, chiefly the former, caused marked disturbances and rapid spread of the fly, principally along the line of communication to the north.

The sudden withdrawal of the human element resulted in marked diminution of fly density, and the advent of rinderpest in 1919 destroyed an important alternative food supply, thus giving further impetus to the reduction.

After a period of 27 years the tsetse had retired to those two points from which it had originally spread.

The Kakitumba centre had not suffered human invasion, as did the foregoing, and no great activity of Glossina has therefore been recorded.

The picture presented is that man himself has proved the greatest factor in that wide and rapid spread of Glossina which Ankole experienced during 1907–1917.