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.

(1) A complete review of the classification and status of the Siricid wood-wasps occurring in Britain is given in this paper.

(2) The biology of S. cyaneus, F., which has been studied at Tubney Wood, Oxford, during the past two years, is described, together with supplementary notes on S. gigas, L.

(3) A study of the forest relations of S. cyaneus at Tubney has shown that this species cannot be considered a primary enemy of healthy green trees. Trees which are favoured by Sirex are usually markedly unhealthy from one cause or another. At Tubney unsuitable soil conditions were the principal factors.

(4) Sirex and Tetropium gabrieli, Weise, the larch longicorn beetle, may occur almost simultaneously as indicators of pathological conditions in larch woods.

(5) In North Devon Fomes annosus, a root fungus, was the predisposing factor in the case of silver fir attacked by Sirex.

(6) Both S. cyaneus and S. gigas may occur in the same tree. This was found to be the case at South Molton, North Devon, in silver fir. S. gigas appears to prefer larger trees, and it is not present in the larch at Tubney Wood, which is in the pole stage.

(7) The primary object of the work was to acquire a knowledge of the parasites of Sirex, Rhyssa persuasoria, L., and Ibalia leucospoides, Hochenw. Both parasites were studied at Tubney, and have already been dealt with (Bull. Ent. Res. xix p. 67, 1928).

(8) It is considered probable that the results obtained in the above study will throw some light on the Sirex problem in New Zealand. Emphasis is therefore laid upon the importance of studying the silvicultural conditions in relation to Sirex attack.

39. Apanteles taeniaticornis, sp. n.

♀. Black; the four front legs (except their coxae), the basal third of the hind tibiae, red testaceous; hind femora red to red-black; basal ventrites and the lateral membranous margins of the 1st tergite pale reddish; palpi and hind tibial spurs white; the 9th to the 12th flagellar joints inclusive entirely cream-white; the apical half of the 8th, and the basal half of the 13th joint, rather pale; ovipositor red; stigma and wing veins dark brown; wings infumated.

The Tachinid fly parasite of Diatraea saccharalis, F. (sugar-cane moth borer), which forms the subject of the present paper, was described in 1916 by Dr. C. H. T. Townsend1 under the name Euzenilliopsis diatraeae. In 1924, Dr. J. M. Aldrich6 pointed out that Dr. Townsend's new genus was untenable and referred E. diatraeae to Lixophaga, Towns., of which Euzenilliopsis, Towns., is now considered a synonym. In certain of the earlier papers in which this fly is mentioned as a parasite of D. saccharalis, it is referred to as Tachinophyto (Hypostena) sp.

The moth, Hieroxestis subcervinella, Wlk., has recently become a pest of economic importance to the banana cultivators in the Canary Islands.

Notes on the genus Hieroxestis and on the synonymy and distribution of the moth are included, and descriptions of the various stages of the insect are given. Details regarding the external morphology and chaetotaxy of the full-grown larva are enumerated, and setal maps showing the distribution of the setae have been added.

The pupa is described in detail, and sex characters are noted.

The economic importance of the pest is considered in its relation to its host-plants, while its method of attack and resulting injuries caused are discussed.

The insect is considered as apodemic in the Canary Islands, and no parasitic natural enemies were encountered.

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.

In October of last year the Acting Game Warden of Uganda, Mr. G. Maitland Warne, forwarded to one of us some newspaper cuttings that he had received from Dr. E. Warren, Director of the Natal Museum. These cuttings, from the Natal Mercury of 1st, 25th and 30th August, set forth an interesting correspondence about the tsetse-fly problem in Zululand, and embodied practical suggestions for control of the fly on a large scale. Some time before, Mr. Cooper, of Cooper's Dip fame, had visited us at Entebbe and discussed the possibility of carrying out experiments on the effect of feeding tsetse on animals regularly dipped in arsenical solutions, the question having been raised in South Africa whether dipping might not prove to be a practical means of controlling fly. At the time of Mr. Cooper's visit it was not possible to undertake the investigations desired, but the arrival of Mr. Warren's communication found us in a better position.

Head antero-posteriorly short; occipital edge sharp; from in front broader than long; eyes moderate, bare; inner orbits a little convergent ventrally; genal space long; face wide; toruli high up, distinctly above the base line of eyes and only slightly below the mid point between the anterior ocellus and mouth-edge. Labrum conspicuous, simple, transverse; mandibles similar, pear-shaped, produced apically into a fine short incurved spine-like tooth. Maxillary palpi three-jointed; labial palpi two-jointed. Inner aspect of galea and opposed side of ligula densely and finely pilose (N.B.—The first maxillary joint has an extremely narrow ill-defined annular base which may represent an obsolete joint). Antennae ten-jointed; scape, pedicel, ring joint, 6 in funicle, and solid club. Scape simple, cylindrical, reaching to about level of anterior ocellus; pedicel short; 1st funicular longer than either the 2nd or the pedicel; funicle (distally) and club somewhat flatly expanded; sensoria numerous, very narrow, short and low, not produced distally. Thorax: mesoscutum separated from scutellum by the broadly meeting axillae, distinctly shorter (measured from its posterior edge to that of pronotum) than scutellum; the latter ending over the metanotum in a short truncate plate; mesopleura posteriorly truncate. Propodeon, smooth between the spiracles; on the middle third are three linear longitudinal thickenings of the integument, the latter pair lying in shallow furrows. Round the spiracles and on the pleura the surface is densely covered with short bristles. Wings: forewings with apical fringe and completely pilose, except on the linea calva. Neuration to about one half. Radius emitted before the costa, long, gently curving towards and subequal to the postmarginal; two bands-one across radius, the other apical. Legs: mid and hind legs elongate, subequal and half longer than fore legs. Hind tibiae widened, with two unequal spurs. Tarsal ungues of all legs markedly unequal, the posterior shorter and more abruptly curved apically than the anterior. Abdomen broad; 1st visible tergite (iii) about half longer than 2nd (iv), 3rd–7th gradually decreasing in length. The last three sternites densely set with short bristles. Ovipositor weakly chitinised.

Colour.—Head irregularly punctate above, yellowish green, the tylus apically and the disc of vertex tinged with brownish yellow; eyes dark grey, ocelli each surrounded on inner side with narrow red rim; head below and rostrum yellow, rostral commissure and apex brownish black. Antennae dark brown, the first segment pale below, shading to black towards the apex of each segment; extreme base of second and third segments and a broad sub-basal annulation on the fourth segment, pale yellow; apex of fourth segment brown. Pronotum dull yellowish green, becoming deeper posteriorly, regularly covered (except for the calli) with small but deep fuscous punctures, which are more dense along the inside of the reflexed lateral margins; extreme humeral angles brown. Propleura yellowish green, punctate, only the outer punctures fuscous. Scutellum dull yellowish green, deeper towards apex, regularly covered with feebly infuscate deep punctures; extreme apex yellow, impunctate. Meso- and meta-pleura yellow, tinged with green towards the basal lateral angles of the pleura, which are rugosely punctate; sterna impunctate, sparsely covered with short erect pale hairs. Hemielytra more or less regularly punctate in series between the veins, dark brown shading to dull blood-red towards apex of corium; veins (including costal and apical margins of corium) yellow, more or less suffused on the disc of elytra with olive-brown; membrane black, the veins olivebrown. Legs yellow, apices of tarsi and claws brown. Abdomen yellow, sparsely covered with short pale obscure hairs.

In 1921, when engaged on work on the small moth-borers of sugar-cane (Diatraea spp.), the writer devised the method and apparatus for the rearing of the egg-parasites (Trichogramma minutum, Riley, and Prophanurus alecto, Cwfd.) of these insects which is described hereafter. It was proposed at the time to investigate further this method of control of small moth-borers, but owing to the change in the writer's position it has not been possible since to do any extensive work in this direction. As the rearing of Trichogramma by this method has been practised since 1921 on a small scale on the two estates on which it was initiated, and has now been adopted in a modified form on two other sugar estates in the Colony, it has been considered desirable to give an account of the method and a description of the appliances used in the rearing of these egg-parasites.

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.

During the latter half of the year 1926, the writer collected parasites from rodents and insectivores in Nigeria. From 1st August to 20th October collections were made in the wet forest near Lagos; 26th October to 2nd November and 10th to 20th November in the guinea grass savannah near Ibadan and Oyo; 3rd to 7th November in the heavy rain forest at Ife; and 28th November to 11th December about Kano on the border of the desert. The animals were usually captured in traps, but a few were shot. They were always placed at once in tight cloth bags or wire cages in order that their ectoparasites might not escape. A general account of the character of the country where collections were made has been given elsewhere (Pearse, Science Monthly, xxv, 1927, pp. 228–239). My thanks are due to the late Major Ingoldby, of the British Museum, and Dr. Karl Jordan, of the Tring Museum. The former identified all the mammals and the latter helped with the identification of several of the fleas.

Many parasitic Hymenoptera are already known to live on lac-insects, and they are of importance either as noxious insects by destroying the Coccid (Tachardia lacca (Kerr)), or as useful insects when parasiting the predators of lac. As a result of the studies of Cameron, Imms, Misra and Mahdihassan, something is already known about them, but the systematic position and the identity of many of the species are still uncertain.

The following descriptions and notes are based upon material received from H. Bennett Johnston, Assistant Government Entomologist, Wad Medani, Sudan, Africa.

(1) The salivary glands of Glossina contain a powerful anticoagulin, which delays the clotting of blood of mammals, birds, reptiles and batrachians. It was found that when the salivary glands are removed from the living fly, it can still draw blood normally and may live long, but sooner or later large clots form in the narrow anterior portions of the alimentary tract, so that the fly can no longer feed and dies of starvation. The purpose of the anticoagulin is to prevent such clotting and blood coagulation in the crop.

(2) The proventriculus and first third of the mesenteron are themselves inert in relation to coagulation of blood, but as removed from the normal fly they contain the anticoagulin which is derived from the salivary secretion.

(3) The hinder part of the mesenteron contains a powerful coagulin, the purpose of which is to neutralise the anticoagulin and cause a rapid clotting, in order to retain the fluid meal in the proper region while draining and assimilation take place, probably also to save strain on the sphincter mesenteri and prevent the occasional loss of food through the anus.

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.

The genus Cicadulina was erected in 1926 (Bull. Ent. Res., xvii, p. 43) to hold C. zeae, a new species injurious to maize in Kenya Colony. Thanks to the kindness of Mr. T. J. Naudé, I have since been able to examine specimens of Balchitha mbila, Naudé, which has been recorded as transmitting the virus of streak disease of maize in Natal. This species is undoubtedly congeneric with C. zeae and differs from typical Balclutha species in the shape of the head and pronotum, and in the venation of the tegmina. It should, therefore, be known in future as Cicadulina mbila, Naudé.

During 1926 and subsequently in September 1927, two species of gall-mites were found on lilac, shoots of which were obtained from private gardens at East Mailing and Sevenoaks, Kent.

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.

The following Aphids were collected by Professor Guido Paoli, of Chiavari in Italian Somaliland and in Eritrea.