A new species of the genus Dicraeus was observed in numbers ovipositing on the heads of rain-fed millet in Upper Volta. In Senegal, it was reared in field trials from heads that had been exposed for one week following onset of flowering, the highest infestation being in heads that flowered during the first two weeks in October. In Nigeria, larval feeding lesions and withering were observed in seeds from individual inflorescences containing pupae. The species is described as D. pennisetivora sp. n. from the adults of both sexes, puparium and third-instar larva. A further three African species that are closely related to it are described from adult material alone, and the characters of the adult terminalia of two further closely related but already described species are given. The six species are keyed. There being no previous description of the larva of any species of this genus, the larva is likened to those of other chloropid genera. The generic diagnosis is modified. It is suggested that within this genus the structure of female terminalia determines the structure of male terminalia, in which case subgenera based upon characters of male terminalia are purely artificial.

Samples of female Glossina morsitans morsitans Westw. were collected in the Zambesi Valley in Zimbabwe-Rhodesia using an electric net and aged using the overian ageing technique. Similar age-structures were demonstrated in the four seasons studied, and the life-table constructed on the basis of the reproductively active members of the population indicates that females produce more than two female offspring in a lifetime. The tsetse population is considered to be regulated by the survival of the newly emerged teneral flies and non-teneral nullipars. The intrinsic rate of natural increase (rm) is calculated from the life-table as 0·01204 for the reproductively active sector of the population.

The vertical distribution of flying mosquitoes beside an area of dry-season irrigated rice-fields was investigated at Bansang in the Gambia. Suction traps were set up at seven levels (0·1, 0·25, 0·5, 1·0, 2·1, 3·9 and 7·9 m) over a dry open field. Vertical distribution profiles were of two types. In the first, mosquito density decreased progressively with height and 80% or more of the total were taken below 1 m. Mosquitoes token included Anopheles gambiae Giles s. l., A. pharoensis Theo., Culex antennatus (Becker), C. ethiopicus Edw., C. neavei Theo. and Mansonia spp. Although the largest catches of A. rufipes (Gough) were taken in the lowest traps, this species Showed a tendency to a bimodal vertical distribution profile during. the early part of the night. In the second type, in which mosquitoes were frequent at all heights, C. poicilipes (Theo.) was the sole example. For the more common species at least, flight altitude declined with increasing wind speed. For a few categories of mosquitoes, flight levels decreased as the night progressed, but the presence of moonlight, or its absence, had no demonstrable effect.

The sexual bahaviour of males of Glossina pallidipes Aust. from the kibwezi Forest Lambwe Valley in Kenya was investigated in the laboratory. Most observatations were on the Kibwezi strain. Three copulatory phases were recorginsed, marked by male courtship, female buzzing, and male jerking with ejaculation. Maturation of copulatory brhaviour occured in advance of ability to inseminate. All males copulated by day 10 and all copulating males inseminated by day 12. Insemination took place only if the jerking phase was present, but neither the occurence of this phase nor the ejection of a spermatophore proved that insemination had taken place. The degree of insemination showed no general relation to age in previously unmated males. The jerking phase was generally shorter in non-inseminating than in inseminating copulations, although duration of copulation showed no obvious relation to the frequency and degree of insemination. The duration of copulation decreased with increasing age of previously unmated males between 10 and 30 days old. Copulation duration was strain-specific while the jerking phase duration was not, suggesting that the length of the pretransmission period (courtship phase plus female buzzing phase) is strain-dependent. In Kibwezi Forest, sexually appetitive (head-down) behaviour among males caught off a moving vehicle was, in geenral, not present among teneral and old males. Head-up and head-down males had small and large amouns of abdominal fat-body, respectively, and both had little gut content. Head-down males had comparatively low activity at dawn and dusk and relatively high middaly activity. The findigs are discussed in relation to the laboratory rearing of G. pallidipes.

Sampling in Northumberland, England, and southern Scotland of pasture soils, the major larval habitat of Hydrotaea irritans (Fall.), showed larvel densities of between 0 and 30/m2; 15 different sites were examined, and all produced larvae. Larvae were found from September until June, larvael development continuing in the soil for about eight months. A study of the distribution within a single field that larvae were not confined to the wooded margins but occurred in significant numbers throughout the field. Higher numbers of larvae were present in the soil beneath cow pats than in the open field, but the proportion relative to the total population is small. Larvae prey was predominantly dipterous and coleopterous larvae. Pupation took place in the top 5 cm of pasture soil during May and lasted until late June. Emergence of adults took place from June until late July; males and females emerged over the same period

The third-stage larva of Oryctes monoceros (O1), a pest of coconut palms, collected in the Seychelles Islands is described and illustrated, and a key is provided to distinguish larvae of this species from those of O. boas (F.) and O. gigas Lap., all of which coexist in parts of Africa.

Moths migrating at Muguga, Kenya, were sampled at 24·5 m and 0·6 m above the ground by light-trap. The larger the species, the greater proportion of the sample it represented at the higher level. This effect was independent of family and morphological type. This result is important in considering the evolution of size with respect to orientation and migratory ambit and the role of downwind migration in population dynamics.

The biology of Aedes geniculatus (O1.) was studied in 1967–73 in Monks Wood National Nature Reserve, an oak-ash woodland, in southern England. Adult emergence from tree-holes occurred from May to September, and the sex ratio was approximately 1:1. Catches on man indicated that the maximum biting densities occurred in July and August and that females spend about two minutes obtaining a blood-meal. Significant positive correlations were found between their unfed weight and the weight of the blood-meal and also between female wing length and fecundity. The mean number of eggs per batch was 70. Studies with bamboo pots used as artificial oviposition sites in the field showed that the seasonal peak in oviposition spanned July and August, daily ovipositional activity was greatest in mid-afternoon and evening and ovipositing females preferred oviposition sites positioned within 4 m of the ground. A small proportion of eggs hatched during the summer in which they were laid, but most hatched in the following spring. Continuous or intermittent soaking failed to induce hatching until this time. In 'the laboratory, partially em'bryonated eggs required a minimum relative humidity of 88% to develop fully, but some embryonated eggs survived at 58%. Some eggs survived for 18–24 months in the field. The sampling of preadult stages dn tree-holes showed that larvae in the first two instars occurred almost throughout the year while third- and fourth-instar larvae were present in spring and summer. Pupae occurred only in the summer. It was concluded that A. geniculatus is univoltine in Monks Wood.

The life-history of Dactylopius austrinus De Lotto on the weed Opuntia aurantiaca, is described. The male moults four times and the female twice. The instars are illustrated. Fecundity is shown to be a function of female density on the plant and of host-plant condition. The sexes were produced in a ratio of about two males to one female.

In studies in southern England in 1967–77, the numbers of Lonchoptera lutea Panz. in cereal crops, such as winter wheat, fluctuated from year to year, depending on an adequate supply of food, provided by decaying litter, for the larvae and on sufficient rainfall to keep the soil surface moist during May and June. Much sunshine was unsuitable for larval growth. The larvae fed mainly on fungal spores and were able to breed in wheat litter in the laboratory. In years when many crop plants were attacked by shoot borers such as Delia coarctata (Fall.) and Oscinelta frit (L.), L. lutea was more numerous than when there were few. Although in most years more males than females appeared in emergence traps, more females than males were caught by sweeping and in light- and suction traps.

During ultra-low-volume aerial applications of endosulfan at 14 g/ha for control of Glossina morsitans morsitans Westw. and G. pallidipes Aust. in savanna woodland in Zimbabwe-Rhodesia, the effects on other organisms were monitored. The numbers and varieties of arthropods, mainly insects, were studied by catches in light-straps and open trays. Mortalities amongst exposed aquatic insects, fish, frogs, mice and stingless bees (Trigona spp.) were noted. No deleterious effect of the insecticide was demonstrated, Other than on fish (Tilapia spp.) in shallow water.

Female Glossina palpalis palpalis (R.-D.) produced larger puparia when they fed on live goats that were injected intravenously with 200 IU of sodium heparinate/day than when they fed on untreated goats or on heparinised goat blood in vitro. Heparin did not produce the same effects when guineapigs were the hosts. Puparia from flies that fed on untreated guineapigs were larger than those from flies that fed on untreated goats. Heparin had no effect on the life-span or fecundity of females that fed on goats or on the life-span of flies that fed on guineapigs. However, the fecundity of flies that fed on guineapigs injected with 500 IU heparin/kg was greater than that of flies fed on untreated guineapigs.

Two years of field trials in Nigeria with the synthetic pyrethroids permethrin, cypermethrin and decamethrin against Glossina palpalis (R.-D.) and G. tachinoides Westw. are described. Laboratory tests were also made against G. morsitans submorsitans Newst. The three pyrethroids were applied successfully from the ground at 0·5%, 0·3% and 0·075%, respectively, to fly resting sites on vegetation using pressurised knapsack sprayers, populations of both species being eradicated after a single application of one insecticide. Following residual spraying from a helicopter, only decamethrin at 30 g/ha achieved complete eradication. It was thought that, with permethrin wettable powder at 200 g/ha, by modifying the spraying equipment and, with cypermethrin, by increasing the dosage to over 150 g/ha, both could be successful in the future. A new ‘sideways’ spraying technique tested using the helicopter gave promising results. Comparatively little harm was done to non-target organisms in the environment after spraying with any of the three pyrethroids, and it is expected that they may gradually replace the chlorinated hydrocarbons in future routine anti-tsetse operations.

Field studies were conducted in Florida to investigate the behaviour of night-flying mosquitoes including Aedes sollicitans (Wlk.), Ae. taeniorhynchus (Wied.), Anopheles atropos D. & K., An. crucians Wied., Culex nigripalpus Theo., Culiseta melanura (Coq.), Deinocerites cancer Theo., Psorophora columbiae (D. & K.) and (Uranotaenia lowii Theo.) in relation to visually conspicuous objects. Adults of all species except Ae. sollicitans were taken in greater numbers in a large weathered plywood suction trap covered with black panels than in one without panels. However, both traps were attractive, as a transparent plastic suction trap covered with weathered plywood panels took larger numbers of all species except U. lowii than a transparent trap without panels. Buried suction traps furnished with visible risers (extensions) that made captures at 1·2 m elevations always captured proportionately larger numbers than buried traps with visible baffles that captured mosquitoes at ground level. A woodland species, C. nigripalpus, was captured in larger numbers toy traps furnisihed with visible risers and baffles than in traps furnished with transparent risers and baffles; however, collections of field species, e.g. Ae. taeniorhynchus, were smaller. The distribution of blood-fed and gravid females in collections from these traps provided some evidence that blood-seeking females are more responsive to visible objects than engorged or gravid females. These results are compatible with the hypotheses that (1) mosquitoes are attracted from a distance to visible objects, (2) in close proximity an avoidance action occurs and mosquitoes then pass over or around the visible object and (3) woodland species approach visible objects closely (<30 cm), whereas field species pass by at greater mean distances. Consequently, a larger percentage of visually attracted woodland mosquitoes than of visually attracted field species will be captured by suction traps. Depending upon trap design and specific behaviour, increasing the visibility of a suction trap can either increase or decrease trap collections