In a search for the forest vector of yellow fever, catches of biting Diptera have been made by various methods in forest trees in Bwamba County, Uganda. The work here reported concerns Tabanids taken in catches made during the period 1944–45.

Three species of Tabanids have been taken in trees during these catches, and one of these, Chrysops centurionis, has proved to be mainly arboreal.

Observations on C. centurionis have shown that its main biting-activity begins just before sunset and reaches a peak during the hour after sunset. Thereafter the numbers taken diminish rapidly, but some activity continues throughout the night.

In the wet-season catches, this species was most prevalent in the forest canopy at heights of 50 to 60 feet above ground. In the dry season the most favourable level was lower, at 20 to 30 feet above ground.

It is suggested that monkeys are the natural hosts of C. centurionis, and that C. centurionis may be the vector of filarial infections among wild monkeys.

It is shown that there is a very close correspondence between the biting-behaviour of C. centurionis and that of the mosquito, A ëdes africanus.

Evidence of nocturnal activity has now been obtained in the case of one species of Tdbanus, three species of Haematopota and two species of Chrysops. It is suggested that there may be some connection between the remarkable eye colours of Tabanids and crepuscular or nocturnal activity.

Records of other Bwamba Tabanids are given.

The new genus Indomerus, described below, belongs to the group Calliptamini and is closely related to the group of genera characterised by a single tooth under the apical lobe of the cercus, but differs from all of them, except Paracaloptenus I. Bol. and Peripolus Mart., by the lobiform elytra. It differs from both Paracaloptenus and Peripolus by the broad, spade-shaped prosternal tubercle. From Peripolus the new genus differs also by the shape of the apical tooth of cercus, which in Indomerus is recurved backwards and covered by the upper lobe, while in Peripolus this tooth is lobiform like the upper lobe; from Paracaloptenus it differs by the excurved posterior margin of the pronotum which in Paracaloptenus is slightly incurved.

The different instars of Agriotes sputator larvae cannot be distinguished by measurements of total length or of various parts of the wireworm.

The number of teeth on the mesothoracic and abdominal spiracles increases with age, and an examination of 700 wireworms showed that the average numbers of teeth on the two thoracic or on all the abdominal spiracles fell into eight groups. These criteria were valid for populations collected at different times of the year.

The number of teeth on the thoracic spiracles of a larva in any particular group approximates to that on the abdominal spiracles of a larva in the next larger group.

The eight groups formed by counting either the thoracic or the abdominal spiracle teeth represent growth stages and not necessarily instars.

The larvae may sometimes moult without growth, a phenomenon probably caused by an inadequate supply of food. At such an ecdysis the number of spiracle teeth does not increase.

The larvae pupate after attaining an optimum size, and reach this size in seven or eight growth stages.

A quick method of determining the growth stage to which a larva belongs is given, whereby more than 80 per cent, of the larvae are placed in their correct growth stages by counting the teeth on one spiracle only ; for less than 1 per cent, of the larvae is it necessary to examine as many as five spiracles ; an accuracy of more than 97 per cent, can be maintained.

The possibility of determining the relationship of growth stage and age is discussed.

The division of the larvae into those which will pupate after seven, and those which will pupate after eight growth stages is apparent at a very early stage in the life history. One larva was found which appeared to be in its ninth growth stage.

The cause of this difference in growth stage number is unknown. It may be due to the size of the egg, to the time of the year at which hatching occurs, or to heredity.

The status of the species of Hypoderma that attack goats, and related species, is discussed. The Oriental species, H. crossi, and the Mediterranean species, H. aeratum, are shown to be distinct. H. aegagri is known in the larval stage only, but as this is identical with that of H. aeratum, the latter becomes its synonym.

Mosquitos were exposed for short contact periods to deposits on plaster blocks from aqueous suspensions of insecticides.

There is an inverse relation between the size of ground DDT crystals fractionated into size ranges by sedimentation and their effectiveness. Smaller particles are more effective than larger ones even when equivalent numbers are compared. Differences in effectiveness are attributed to differences in the amounts of insecticide picked up and retained by the insect.

There is no significant increase in kills of mosquitos exposed for the same contact period to dosages of 10–20 micron DDT crystals above 3 mg. per sq. ft. “Persistence” of deposits of these crystals, however, increases as the dosage increases.

Crystal length alone is not critical, for fine 60 micron DDT needles are slightly more effective than ground crystals in the 10–20 micron range. The shape and mass of crystals together influence pick-up and determine their effectiveness.

There is also an inverse relation between crystal size and effectiveness of methoxychlor and DDD. The effectiveness of Compound 497 and of the gamma isomer of benzene hexachloride is influenced much less by particle size than is that of DDT.

The inert ingredient of a wettable powder has a masking effect on the insecticide, and this is intensified as the proportion of diluent to insecticide increases.

The availability of the deposit from an aqueous suspension of DDT crystals depends largely on the nature of the surface to which it is applied.

The geographical distribution in the African Continent of very few of the species of Ixodoidea has been fully determined. Rhipicephalus sanguineus (Latr.) and certain species of Boophilus are known to be widely distributed, while others, such as R. duttoni Neum., have been recorded from only one or two localities. The present study was primarily undertaken to determine the genera and species of ticks occurring in Nyasaland, but it is hoped it will contribute to the wider problems of the distribution in Africa of the several species.

The genus Pseudiastata was described by Coquillett (1908) for a single species from Maryland, P. nebulosa, which he placed in the family Geomyzidae. Melander (1913b) referred it to the Drosophilidae and he has been followed in this by subsequent workers. The convergent anterior frontal bristles are suggestive of Milichiidae, however, and the genus may run to that family in some keys.

While investigating the biological control of certain Hepialids, a very interesting Ichneumonid parasite, Alomya debellator (F.) was reared from the pupae of the Swift Moth, Hepialus lupulinus (L.).

The systematic position of this parasite has been thoroughly investigated and the members of the special sub-family, Metopiinae, to which it has been assigned, are characterised by the possession of only one trochanter on each foreleg. A. debellator is the sole representative of the tribe Alomyini.

After extensive collecting, and a thorough search of the literature, the conclusion has been reached that the distribution of this parasite is fairly local, but its range in Great Britain and certain other European countries is wide. As a result of the present study H. lupulinus has been definitely proved to be the host of A. debellator.

A fairly full account of the life-history of the parasite has been worked out, and amongst other things, a point of special interest is the arrest in development which occurs in the first-instar larva. Possible explanations of this phenomenon are discussed.

The morphological and anatomical structure of the larva have been fully investigated and described, and useful diagnostic characteristics both for the primary and mature larval stages, have been discovered.

The paper concludes with a discussion on the potential value of A. debellator as a factor in the control of H. lupulinus, and other allied species belonging to the genus Oncopera in Australia. It is maintained, on the evidence collected, that this parasite in some areas is probably the most important single factor of biological control. A note on the feeding habits of Hepialids, and a few remarks about the collecting of parasitised material are appended. Altogether some 7,000 specimens of H. lupulinus larvae and pupae many of which were parasitised by A. debellator were collected from the Willingham area of Cambridgeshire.

This paper deals with the aerial curtain method of spraying flying swarms of locusts with insecticide from aircraft.

Equations are developed for calculating the dosage deposited on locusts in single spraying runs under idealised conditions. Graphical methods of solving the equations are described together with a simple method for obtaining the summed effect when a number of spraying runs are carried out in a regular sequence to form an aerial curtain.

There is an optimum combination of spray droplet size distribution and spraying height according to the depth and density of the swarm, but good performance can be obtained with a single fixed droplet size distribution. A fine spray is recommended for the attack of flat-topped, shallow swarms, but a coarser spray is required to penetrate adequately into deeper and denser swarms.

The efficiency of application of the insecticide solution, calculated as the proportion of lethal doses actually applied to those potentially available, may be as high as 10 per cent., but varies rapidly with spray droplet size and swarm characteristics.

The numerical values given may need some modification in the light of further experimental and field data, especially in regard to locust airspeed in the swarm and the effect of droplet size on mortality.

Brenthia leptocosma is a Microlepidopteron which feeds upon the Boraginaceous bush, Cordia macrostachya. This plant, since its accidental introduction into Mauritius about 1900, has become a pest of considerable agricultural importance. Other food-plants are C. myxa, C. abyssinica and C. holstii, which are all unimportant trees. B. leptocosma has been recorded only from Mauritius. It is not likely to be indigenous for it is restricted to Cordia species, none of which are considered to be native to Mauritius.

The morphology and biology of the various stages are described.

The distribution of B. leptocosma is that of its food-plants: it is extremely numerous in all regions below about 1,500 feet, which is the upper limit for C. macrostachya. The abundance of the moth is due to the excessive growth of C. macrostachya. Owing to its mode of life, it is of no value as a controlling agent of C. macrostachya.

Larval and pupal parasites are recorded.

A paper by the present writer on an Ichneumonid parasite of Hepialus lupulinus (L.) under the name Alomya debellator (F.) appeared in the last issue of this journal (1950). It now transpires that this Ichneumonid is not A. debellator but Ichneumon suspiciosus Wesm. This error was pointed out, as soon as the paper was published, by Mr. J. F. Perkins of the British Museum, and agreed by Mr. G. J. Kerrich of the Commonwealth Institute of Entomology, both of whom, as specialists in the Ichneumonidae, recognised the illustration produced from a drawing prepared by Mr. A. J. E. Terzi as representing a species of Ichneumon, probably I. suspiciosus. The actual specimen illustrated has been traced, and its identification has been confirmed by Mr. Perkins as Ichneumon suspiciosus Wesm. It is certain, moreover, that all the parasite material involved was this species and not A. debellator.