The holotypes and allotypes of all species described as new in this paper are to be deposited in the British Museum and paratypes in the United States National Museum. All the species described in this paper are parasitic in scale-insects or mealybugs.

Some of the classifications presented in these papers on African Encyrtidae are tentative only, for in the case of closely related variable species it is impossible to make final identifications on the basis of a few museum samples. The exact degrees of relationship can be expressed only when the insects are known intimately throughout their entire range and a knowledge of the limits and degrees of variation obtained. Even with this knowledge it is not always possible to make final determinations with assurance.

1. The ecological study of Sirex and its parasites was begun in 1927 and continued while making large-scale collections of the parasites for shipment to New Zealand with the ultimate object of the control of Sirex noctilio, a species of woodwasp which has been established in the Dominion for many years.

2. A brief outline of the life-cycle of Sirex and the parasites is given. The difference in the method of attack by the parasites on the host is described, and some points of interest in connection with insect behaviour are discussed.

3. The methods of collection are described and particulars given about the number of parasites collected.

4. The inter-relationship of the host and parasites is discussed. It is shown that a single generation of Sirex can support three generations of Rhyssa and one generation of Ibalia, and that the effects of parasitism by Rhyssa are cumulative. The percentage of parasitism by Rhyssa cannot, therefore, be calculated on the results of any one year. Rhyssa is intrinsically superior to Ibalia and super-parasitism of Ibalia by Rhyssa is of very frequent occurrence. It is shown that the figures for parasitism by Ibalia obtained by the dissection of Sirex larvae collected from a number of logs, over a period including summer months, are liable to be very misleading.

In this paper I am redescribing and giving some interesting, new, biological information with regard to two species of Apanteles, of which one, A. compressiventris, has not previously been recorded in the Old World, and the other, A. plutellae, not previously recorded from the Western Palaearctic Region; and I believe that it is better to communicate this information at this time rather than to wait until the completion of the monograph upon which it is known that I am engaged, a matter yet of some years.

In 1932 on an expedition in Brazil, Dr. J. G. Myers, of the Imperial Institute of Entomology, while in search for suitable parasites for introduction into this and other colonies in the West Indian area, discovered the Tachinid fly Metagonistylum minense, Towns., known generally now as the Amazon fly, as an important parasite of Diatraea saccharalis, F., in the vicinity of Santarem on the Amazon, and as the result of his investigations there, formed the opinion that it would be a suitable parasite for introduction into British Guiana.

1. Serial examinations of the degree of infestation of thirty-five flocks during a nine-year period in Argyllshire, Perthshire, Selkirk and Northumberland, showed that tick incidence is greatest in spring and decreases markedly in early summer. Evidence is given of a similar periodicity in North Wales.

2. Evidence is given of the occurrence of a slight recrudescence of activity in autumn, and of the almost complete absence of activity in winter.

3. The spring curve of activity terminated in early May in Argyllshire, in the middle of May in Perthshire, and towards the end of May in the Borders and Northumberland.

4. The estimation of the relative annual infestation, e.g., in relation to the question of spread or increase of ticks, by single annual counts is shown to be quite unreliable.

5. No evidence was obtained of an increase in density of ticks in any area during the period of observation.

6. The seasonal periodicity in activity was found to bear no relation to the density of stocking of the ground by sheep.

7. The seasonal activity of ticks in Argyllshire, Perthshire, Selkirkshire and Northumberland, was found to be related to the air temperature, expressed as the weekly average of maximum temperatures. The limits of the air-temperature range corresponding to active tick infestation are 45°F. and 60°F. (average weekly maximum).

8. The curve of tick infestation during 1937 on a moor in North-east Scotland was found to differ markedly from the normal, and the possible explanations of the discrepancy are discussed.

This paper deals with seven Indian species and one African variety belonging to the subfamilies Spathiinae and Doryctinae. Four of the species are important parasites of the cotton stem weevil, Pempheres affinis, Fst., and are described as new in compliance with an urgent request for their names.

These keys and illustrations have been prepared in response to many requests. They concern only those species of Anopheles which have been recorded as occurring in West Africa south of the Sahara Desert as far as the equator. Much of the material has been derived from the recent Monograph by the late Dr. A. M. Evans on the Anophelines of the Ethiopian Region published by the British Museum in 1938. Personal acquaintance with the Anophelines of East and South Africa and examination of the specimens in the collection of the Department of Entomology of the London School of Hygiene and Tropical Medicine have assisted in the preparation of the keys.

The Chalcidoidea mentioned in this paper are mostly parasites of the cotton stem-weevil, Pempheres affinis, Fst., in South India. They were bred by Mr. P. N. Krishna Ayyar during the years 1935 to 1938 and were sent in various collections to the Imperial Institute of Entomology for study. Another species, parasite of the Coconut Hispid, Promecotheca papuana, Csiki (antiqua, Ws.), has been added here, its description having been required for biological studies.