Pin-hole borer damage to timber, caused by beetles of the families Scolytidae and Platypodidae, is associated chiefly with recently felled logs and occasionally with standing trees which are in an unhealthy condition. Information collected within recent years by the Forest Products Research Laboratory, Department of Scientific and Industrial Research, suggests that attack in standing trees may, however, be of more frequent occurrence than has been commonly supposed. In this connection, an interesting case of damage to English ash by the Platypodid beetle, Platypus cylindrus, F., is worthy of record.

In 1927, 1931 and 1935, the writer published three papers on the food-plants of Nigerian insects in this Bulletin (18, pt. 1 ; 22, pt. 2 ; and 26, pt. 2). The present paper contains additional data obtained between November, 1934, and March, 1936. On the advice of the Botanical Section, Nigerian Agricultural Department, certain changes have been made in the nomenclature of economic plants. In the previous papers the nomenclature employed in the Kew Bulletin entitled “ The Useful Plants of Nigeria ” was adopted. The following list shows the English or native name of the crop and the old and new scientific names.

Sheep scab has existed from early times. It was known to the ancient Greeks and Romans ; it was familiar to the Hebrews ; and writers on agriculture in the Middle Ages were acquainted with its ravages, and suggested means of preventing and curing it. Laws to control the disease were introduced in Britain at the beginning of the eleventh century, and subsequently other countries also adopted legislative measures against it. Regulations have been renewed and amended from time to time to conform with the progress made in the studies of the disease and its cause. The strictness with which they are applied vary in accordance with the economic importance of the sheep industry in any particular country, and their success as preventive measures is dependent upon their stringency and upon the co-operative support given to them by all sheep-owners.

1. The main food hosts of Glossina swynnertoni in a district of Tanganyika appear to be (a) one or more Bovids, perhaps kudu or roan, exhibiting a close blood relationship to ox or buffalo ; (b) giraffe ; (c) pig. There is evidence that monkey or baboon is also made use of and that zebra definitely is not.

2. With regard to G. palpalis on Maboko Island, crocodile and hippopotamus are important hosts. But they are far less important than we had supposed. The majority of flies appear to have fed on some animal not yet determined.

The species of Encyrtidae and Aphelinidae described as new or listed in this paper were among a lot of Coccid-inhabiting parasites received from the Entomological Branch, Department of Agriculture, New South Wales. This material was obtained in Kenya and Uganda during August to October 1935 by William B. Gurney, Entomologist, Department of Agriculture, N.S.W., mostly from Ceroplastes spp. Except for Scutellista sp., only species of Encyrtidae and Aphelinidae are reported upon in this paper. Mr. Gurney visited Kenya and Uganda for the purpose of finding and despatching living parasites of White Wax Scale (Ceroplastes spp.) in East Africa to establish in New South Wales for control of White Wax Scale of citrus trees and shrubs. While in Africa he arranged for Mr. H. Wilkinson, Entomologist, Kenya, and Messrs. H. Hargreaves and T. H. C. Taylor, Entomologists in Uganda, to continue to despatch further consignments of parasitised White Wax Scale after he had left.

1. Measurements of the spiracles and the tracheae of 5th instar hoppers and adults of Locusta and adults of Schistocerca have been made (see Tables I, II and IV). These measurements show that particles of dust which had passed a 300 B.S. Sieve (i.e., under 0·053 mm. in diameter) are small enough to enter all the spiracles and that the particles which had passed a 150 B.S. Sieve (i.e., under 0·104 mm. in diameter) could enter spiracles 1 to 4 and 10.

2. It has been proved by the presence of particles of dust in the respective spiracles, that spiracles 1 to 4 are inspiratory in function and spiracles 5 to 9 expiratory under all conditions, while the function of spiracle 10 is expiratory when the locust is flying and inspiratory when it is motionless.

3. The quantity of dust present in the tracheae increases with the length of exposure to the cloud of dust ; the quantity present after 10 seconds exposure is not regarded as sufficient to kill the locust.

4. The action of external poisons is thought to be by direct penetration of the integument or through the nerve endings or both.

5. The results given in this paper suggest that further work on the action of poison dusts should be concentrated on the investigation of direct penetration of the integument and of the nerve action, rather than poisoning through the respiratory system.

In 1935 during entomological investigations related to an outbreak of jungle yellow fever in Restrepo, Colombia, I captured a female Anopheline which shows morphological details justifying its description as belonging to a new species of a new subgenus. I also found specimens of a new species of Goeldia. These two species are described in the following pages.

The Seasonal Factor.

1. The period of stress due to extreme climatic conditions is far shorter in the forest than in the meadow-pan.

2. G. tachinoides is primarily dependent upon riverine vegetation or residual forest, and has only a very limited wet season spread. G. submorsitans is primarily an open woodland fly with great powers of dispersal which are annually checked by adverse climate that enforces a temporary dependence upon the riverine forests.

3. G. tachinoides abounds within the stream-bed or residual forest ; G. submorsitans abounds on the forest fringe.

4. The dispersal of both species is closely associated with evaporation and saturation deficiency. A mean monthly evaporation of 20–28 cc. and a saturation deficiency of 5 to 8 millibars results in maximal dispersal ; dispersal yields to concentration as the evaporative power of the air increases above these zones.

5. The extent of the annual dispersal is indirectly governed by the duration of the wet season—the longer the season the more extensive the dispersal.

6. The population of G. submorsitans steadily increases throughout the rains as the evaporation falls, and becomes maximal towards the end when the evaporation is in the optimum zone (20—25 cc.) ; density steadily falls throughout the dry season as evaporation rises, and becomes minimal at the end when evaporation is maximal. G. tachinoides is believed to behave similarly, but the optimum zone of evaporation is probably about 6 to 10 cc.

1. Details are given of the distribution of the eight species of tsetse occurring in the Tanganyika Territory (G. brevipalpis, G. longipennis, G. fuscipleuris, G. palpalis, G. morsitans, G. swynnertoni, G. pallidipes, and G. austeni).

2. The effect of past climatic changes on the present distribution of some of the species is discussed in a somewhat speculative manner.

3. The detailed information is summarised in a general description and map of the fly-belts of the Territory.

4. The effect of certain broad vegetation types and major topographical features on the distribution of species of tsetse in Tanganyika are discussed.

5. The effect of the major topographical features in limiting the distribution of the fly is always found to reside in some accompanying vegetative or climatic feature.

6. Possible and likely extensions of the fly-belts are briefly indicated ; if these should take place, but little of Tanganyika Territory would remain uninfested by tsetse-fly. The possibility of natural retreat of fly-belts is also discussed.

7. A few details are given of the habits and habitats of some of the lesser known species (G. longipennis, G. fuscipleuris and G. austeni).

It is a remarkable fact that out of the six commonly occurring species of the family Scarabaeidae (chafers, white grubs) in Britain, five are constantly reported as causing damage, either as grubs or as adults, to agricultural and forest crops. Thus, of the six species listed in Table I, only the last named, Anomala aenea, de Geer, which is very abundant locally on sand-dunes, finds agricultural conditions unsuitable to its existence.