1. A sketch is given of the Malaria Control Organisation in Service areas in Mauritius with a summarised history of malaria work in the Island since the first epidemic in 1865.2. Keys to Mauritian Anophelines and their larvae with notes on their field recognition characters are followed by data on the distribution of adult Anophelines in the Colony and their relation to malaria intensity in different areas. A. melas appears to be absent from coastal swamps.3. The influence of a number of environmental factors is discussed. It is concluded that temperature is an important limiting factor generally in winter and perennially in the highlands (above 1,000 ft.), but that the flushing action of heavy rains and probably the precipitation of food supply by colloidal iron moving under high rainfall conditions (over 100 ins.) from ferrugineous lavas both play their part in the natural control of A. funestus and A. gambiae.The behaviour of A. gambiae with respect to temperature is expressed by an area enclosed by two symmetrical catenary curves, that illustrate well the adverse influence on development of low temperatures normally occurring in winter on the coast and all the year round in the residential uplands above 1,000 ft. The thermal death point of A. gambiae larvae is about 42°C. and that of A. funestus 40°C. and the lower limit of larval activity is 16·5°C. A. gambiae develops most rapidly at an estimated temperature of about 37°C.

A severe outbreak of the Spruce Sawfly (Diprion polytomum, Htg.) in Eastern Canada led to a request to Farnham House Laboratory to investigate, and if possible collect and export, the parasites of this insect in its native home in Europe.Work started in 1932 and it was found that D. polytomum was a comparatively rare insect in Europe, though widely distributed. It is heavily parasitized, 31 species of Hymenopterous and Dipterous parasites having been found up to the present. Nearly twenty-eight million parasitized cocoons and eggs of this and other species of Diprion have been collected and despatched from Europe, and work is still continuing.Previous to the present work only 13 species of parasites, a list of which is given, were recorded from this host.Of the 31 species now known, 15 are primary, 5 can be primary or secondary, and 9 secondary only; in 2 cases the status is not known.Descriptions of all the species are given and in the case of the obligatory and facultative primaries, the biology and immature stages are also described and notes added on their suitability for introduction into Canada. A key to the adult parasites is given, and a key to the larval stages of the primary and facultative primary parasites. Some practical notes are also given, including methods of accelerating the emergence of parasites in winter and methods of preparing parasite larvae for examination and identification.

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The first record of a Melolonthid (cockchafer) larva as a pest of sugar-cane in Tanganyika was in April 1941, when about 25 acres on the Arusha Chini (Moshi) estate of the Tanganyika Planting Company were found to be infested. Subsequently, the main swarming period of the adult beetle has been observed from the beginning of October to late November, and a minor period at the onset of the long rains in March. The identity of the pest was established in 1943 as Cochliotis melolonthoides (Gerst.), a native species fairly closely allied to the European cockchafer, Melolontha. Several other associated species of minor importance have since been identified. Field and laboratory studies have also been made by W. V. Harris, and his recommendations have enabled a certain measure of check to be kept on the intensity and spread of the damage. The writer succeeded Mr. Harris at Morogoro, and after nearly two years' study of this problem wishes to acknowledge the numerous and valuable data which have been freely drawn upon in preparing the present paper, which is an attempt to summarise the facts known about the cane beetles and the suggestions which have been made for their control. The present recommendations are made in the light of over ten years' study of methods of control of the sugar-cane beetle, Clemora smithi (An*.), in Mauritius and of two seasons' field observations on Cochliotis melolonthoides on the above-mentioned infested estate in Tanganyika. The method of chemical control by BHC-dust application in the furrow has since been tested over five years and whilst it has been shown to be essential to protect the virgin canes and to a certain extent the first ratoon, the problem of protecting the second and subsequent ratoons remains a matter for future investigation.Sugar-cane in various stages of development, both as plant cane and ratoons, begins to show serious signs of root infestation each year in July, and by September or October a seriously infested field will show patches of stunted plants with curled and yellowed leaves; the patches tend to follow the main irrigation furrows. The stools of cane can be lifted easily from the soil, their roots having been severed by the feeding of the larvae. In young plantations, the young shoots and roots are eaten and the larvae then hollow out the setts. In this way, fields which gave 45 to 80 tons per acre in virgin fields and 30 tons in ratoon cane may be reduced to single-figure yields. The infestation spreads but slowly and takes several years to attain its zenith in one field. The environmental resistance to the insect is then slowly built up in the form of insect parasites and predators, fungal and bacterial diseases and these, aided by vigorous cultural measures enable the land to be cultivated profitably once more until the beetle again builds up a population of damaging intensity. The present position is that several hundred acres are gradually being won back to cane cultivation with the beetle advancing slowly but steadily over the rest of the estate. Success i...