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.

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.

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.

(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.

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.

Near O. flavicornis, Lac, but smaller, the 8th and 9th joints of the antennae more strongly transverse, the fore-parts less closely punctured. Head extremely finely, sparingly punctured. Antennae with 3-jointed club, the 8th and 9th joints twice as broad as long, the 10th short, oval. Thorax twice as broad as long, very finely, moderately closely punctured. Elytra a little broader than and about half as long again as the thorax, very finely, moderately closely, asperately punctured. Abdomen strongly narrowed from base to apex, finely and moderately closely punctured on the anterior segments. The whole insect covered with a short, stiff black pulescence, the fore-parts with an extremely fine, more or less transverse ground sculpture.

Rhyssa persuasoria and Ibalia leucospoides, both parasitic on Sirex cyaneus, have been studied at Oxford.

Rhyssa lays its eggs in the burrow of and near to the almost or quite full-fed host larva or the pupa, by piercing the solid wood with itsovipositor. Feeding is entirely ectoparasitic and takes only a few weeks, during which the host larva may burrow a little further. The winter is passed by Rhyssa as a resting larva. Pupation takes place in the spring, and the whole life-cycle normally occupies one year.

Ibalia oviposits in the young larva just before ormore rarely just after hatching, utilising the oviposition-bores of the Sirex for this purpose. The first-stage larva is elongate, with sickle-shaped mandibles, and larval feeding seems wholly endoparasitic. Sirex larvae parasitised by Ibalia confine their boring largely to the outer portions of the trunk, and usually make their final cell just under and approximately parallel to the surface. The life-cycle of Ibalia requires at least two years.

Owing to the very different instars which they attack, there seems no risk of superparasitism of Ibalia by Rhyssa or vice versa, and it is therefore suggested that both species be introduced into New Zealand as a measure against Sirex juvencus, which is there very destructive to plantations of Pinus radiata.

The following paper is intended only as a preliminary revision of this large and exceedingly important group of parasites, and it is the outcome of some six months' work on a small portion of the large mass of material awaiting identification in the collections of the British Museum and of the Imperial Bureau of Entomology. The writer not only has had access to all the types which he required to see that had been deposited in the British Museum, but also was so fortunate as to have been able to arrange with the authorities of both the United States National Museum and the National Hungarian Museum for exchanges of cotypes where sufficiently long series were available, and consequently has been able to examine and include in his key all, or the large majority of, the species that have been described from the Indo-Australian region by Continental and American writers. It should be placed on record that, in addition, the National Hungarian Museum, when not in a position to exchange cotypes, was so good as to forward to the writer on loan the types themselves. With all this extremely kind co-operation, therefore, it has been possible to make this paper tolerably complete; and for purposes of comparison it has been thought desirable to include in the key numerous Palaearctic and Ethiopian species, the types and cotypes of which are to be found in the British Museum.