In a survey in 1976–79 in Botswana, more than 14000 adult ticks were collected from cattle and other domestic and wild animals and identified. Larvae and nymphs were also collected but not counted. Comparison with previous records indicates that some species, particularly Amblyomma hebraeum Koch and Boophilus decoloratus (Koch), are becoming more numerous and widespread, probably due to cattle movements and favourable climatic conditions. Haemaphysalis aciculifer Warb. was found for the first time in Botswana. The counts from complete collections of ticks from groups of three cattle are analysed, host-parasite lists are given and the results of a few acaricide resistance tests are recorded.

The flight performance of a laboratory population of Triatoma infestans (Klug) was tested on a flight balance. Bugs adopted a typical flight posture which is described. They were capable of steady flight and produced reasonable amounts of lift. Flight durations were generally short, but capacity for flight rose to a peak in the third week after adult eclosion with the longest recorded flight being one of 2 h 40 min by a male. Sexual differences were slight; males had a slightly higher mean wing-beat frequency (57·8 Hz against 55·6 Hz), and a few more females than males made longer flights. Differences were noted between short and long fliers; the latter producing significantly more lift and showing signs of a flight pattern divisible into rising, steady and falling phases. The short fliers showed only rising and falling phases. Lift and wing-beat frequency were correlated, but it is evident that lift also depends on other variables such as stroke-plane angle, body angle and wing-beat amplitude, which are discussed.

Coccinellids reported to be feeding on the diaspidid Chrysomphalus aonidum (L.) infesting coconut palms in Gujarat, India, were found to belong to an undescribed species. This is described here as Sukunahi-kona popei sp.n. and is compared with other species of the genus. A key to the species is given. This is the first record of the tribe Sukunahikoni in India.

A revised key is given to the Enicospilus antefurcalis (Szépl.) species-group, some species of which are parasites of Lepidoptera of economic importance, of the Afrotropical region. One Oriental species, E. laqueatus (End.), is recorded for the first time from Africa and two species, E. watshami sp. n. and E. polemus sp. n., are described.

Ten large suction traps were operated continuously, day and night, throughout the wet season of 1977 at four widely separated places within the area of the Onchocerciasis Control Programme in the Volta River Basin (OCP) in West Africa. At least ten species of Simulium s.l. were trapped and the daily catches were analysed qualitatively and quantitatively. In the total catch of 9189 flies there were 187 males and 9002 females; among the latter only six were gravid and only five contained a full blood-meal. Cyclical changes in numbers, with periodicities ranging from 10 to 20 days, were analysed in series of overlapping Gaussian distributions, each possibly reflecting the rise and fall of a distinct population. Similar patterns in the sequence of cycles were shown by S. adersi Pomeroy, S. ruficorne Macq., S. evillense Fain, Hallot & Bafort and other species at a particular trapping site. Patterns differed between catching sites, except in the general tendency for population maxima to increase during the season. In some species, notably S. adersi, populations decreased in late July and early August before increasing greatly in September (end of the rains) prior to the October onset of the dry season. Among the species caught, S. evillense was present at all four trapping sites and particularly abundant at two of them, although the species has never been recorded before in West Africa and its early stages remain undiscovered there despite special searches for them since the capture of adult flies. By contrast, only four specimens of S. hargreavesi Gibbins were trapped although this species is abundant in local breeding sites. Diel flight periodicity was recorded over a one-week period at the extreme end of the wet season and showed that most flies were caught in the daytime; S. ruficorne showed a greater tendency to a unimodal periodicity than other species. The behaviour of flies at the time of capture is discussed, including a consideration of the local wind speeds and the air speed of Simulium s.l.

Wild adults of Glossina morsitans morsitans Westw. and G. pallidipes Aust. were caught in a trap baited with carbon dioxide and acetone near Chimotsi Dam in the Zambezi Valley, Zimbabwe. The design of the trap was such that flies were induced to move into a sterilising chamber, where they were treated with a spray of the chemosterilant metepa, after which they were automatically released back into the environment. Exposure to a spray of 0·2 s duration produced between 94 and 100% sterility, with very low mortality. The sterilising unit, its action and performance are described.

In field studies on Glossina morsitans morsitans Westw. and G. pallidipes Aust. in Zimbabwe, various traps baited with attractive odour were used to study the behaviour of flies in each of several stages of response to traps, from the stage of being several metres from the trap to the stage of being retained in a cage on the trap. The numbers of flies that were caught by electrocution, or were observed, as they moved forwards through the stages of trapping were compared with the numbers caught or observed moving in a reverse direction. A variety of stimuli and modifications were investigated for their effects on these movements, leading to provisional recommendations for improving the speed and efficiency of trapping. The most important recommendations were: the outside of trap should be white, with black near the basal entrances, the entrances should be provided with tunnels projecting into trap, and the inside of trap should be made white at base and black at top. The top of the trap should be an open-ended tube around the cone of netting that leads to the retaining cage. Data for Stomoxyinae, non-biting Muscidae and Tabanidae are also presented.

Based on previous studies of the trap-orientated behaviour of Diptera, a variety of new traps was designed to maximise the speed and probability of capturing Glossina morsitans morsitans Westw. and G. pallidipes Aust. arriving near traps, and to minimise the probability of capturing other flies. In Zimbabwe, catches were made with these traps in the presence and absence of carbon dioxide and acetone as odour attractants, leading to the identification of a simple trap for which the probability of capturing Glossina spp. was up to twice as great as it was for a standard biconi-cal trap, and for which the probability of capturing other Diptera was very much less than it was for the biconical trap. The probability of capture by the simple trap was 100% for G. pallidipes, 51% for G. m. morsitans, 6% for Stomoxyinae and 1% for non-biting Muscidae. Half the tsetse that arrived near the simple trap were captured within 5 min of arrival. The number of tsetse that contacted simple targets designed to expose flies to insecticide amounted to 32–263% of the catches of a biconical trap. The use of traps and targets for tsetse control, and the procedures for trap improvement, are discussed.

Coccus celatus De Lotto is now established on coffee in Papua New Guinea where it is causing some concern. As a result of studying extensive collections of this species from the Sudan and Papua New Guinea, it is now possible to synonymise the name C. consimilis De Lotto with C. celatus. An account of the distribution and host range is given.

The recent attack by Pulvinaria iceryi (Sign.) on sugar-cane in Mauritius is discussed in the context of other attacks by sap-sucking Hemiptera in the Mascarenes. P. iceryi is compared with its allies P. elongata Newst., P. saccharia DeLotto, P. sorghicola De Lotto and P. tenuivalvata (Newst.). The name of P. longisqua De Lotto is sunk as a synonym of P. elongata and a key is presented for the five related species.

Variations in density of adults of Anopheles merus Dön. in Jimbo Village on the Kenya Coast were found to be correlated both with rainfall and with salinity at their breeding sites. Densities started to increase at the beginning of the rains when several breeding sites were formed. This was followed by a decline in numbers resulting mainly from the decrease in salinity in the semi-permanent breeding sites. A second rise occurred after the end of the rains, corresponding with an increase in salinity in the semi-permanent breeding sites due to evaporation. Peak density coincided with salinities of 30–50% sea water in the breeding sites. Laboratory breeding experiments showed that the larvae were usually capable of completing development in 0–100% sea water, with optimum development at 0, 40 and 60% sea water. Failure to complete development in 100% sea water at certain periods of the year indicated that there could be some seasonal variation in salt tolerance. The larvae were also found to complete development in alkaline saline water collected from an inland location around Lake Jipe in Kenya. The LC50s of sea water for first and fourth-instar larvae after exposure for 2 h were 135·0 and 930·0%, respectively. First-instar larvae were less to lerant of sodium chloride than of sea water of equivalent strength. The LC50 of sodium chloride for first-instar larvae was only 102·5%, sea water equivalent. In tests against first-instar larvae of other soluble chemical salts normally present in sea water, the highest LC50 (122·0g/litre) was of sodium sulphate and the lowest (10·5g/litre) of potassium carbonate.

Alcestis ingens sp. n. is described from a series of adults collected in stands of hybrid cacao between Ilhéus and Itabuna, Brazil.

Dimorphopterus cornutus novaeguineae subsp.n. is described from Papua New Guinea. Adults and immatures were collected from dying rice and a lawn of carpet grass (Axonopus compressus). Members of the genus Dimorphopterus and allied genera are known as chinch bugs and damage Gramineae in the tropics and subtropics. The differences between this subspecies and D. cornutus cornutus Slater are illustrated and described in detail.

Two mark-release-recapture experiments with Anopheles culicifacies Giles were carried out immediately before and one month after a round of malathion spraying of houses (at 2 g/m2) in a village in north-western Sri Lanka. In the first experiment the measurement of bidirectional movement of females collected in two halves of the village showed that movement was somewhat affected by wind direction; the percentage of migrants moving partially upwind was greater (11·4) than that in the reverse direction (6·4). The best estimates of daily survival were 0·79 before spraying and 0·44 after spraying; population sizes were about 44 500 and 1300, respectively. The proportion of females resting in the collection huts rose after spraying. The results are discussed with reference to the evolution of insecticide resistance in populations under insecticidal pressure and those populations not selected by spraying.

A method for screening resistance of cowpea (Vigna unguiculata) to the legume pod-borer Maruca testulalis (Geyer) was developed. Several damage parameters were measured, including damage to stem, flowers, pods and seeds. Some of these parameters were assessed in more than one way. A decision was made at the end of the study as to which parameters were most appropriate for a field screening methodology. A plant resistance index, Ipr, was generated to aid in this decision. Based on this, it was concluded that flower, pod, and seed damage measurements provided the most important assessment of resistance to the borer. The larval population in the flowers showed marked differences in infestation levels between cultivars and is suggested as a means of comparing results in the future. Based on the methodology described, TVu 946 was the most resistant cowpea cultivar in every category of assessment. Five other cultivars were also selected for further evaluation as probable resistance donors: Kamboinse Local, TVu 1, VITA-5, TVx 3890–010F and VICAM-1/SP. The rationale behind the development of a field-screening methodology and some of its shortfalls are discussed.

Alate exules of Rhopalosiphum padi (L.) were flown in a flight chamber for three different flight times: 1 min, 5 min and 25 min. The rate of climb was recorded continuously during flight. Afterwards, the aphids were forced to land on either wheat or potato and settling behaviour was recorded. The settling response was strengthened with increasing flight time on both plants. The aphids spent more time walking and made more probes on potato than on wheat after 25 min of flight. The rate of climb was the same immediately before landing as immediately after a spontaneous re-take-off, except after a 25-min flight and landing on potato when the rate of climb was significantly higher after re-take-off. Comparison with Aphis fabae Scop. from other investigations showed that the change in settling response with flight time was similar for the two species. R. padi seemed less able to discriminate rapidly between host and non-host plants than A. fabae. It is concluded that its behaviour does not hinder R. padi from being a vector of stylet-borne potato viruses.

Field experiments in England with traps baited with allylisothiocyanate (ANCS) showed that females of Delia radicum (L.) were distributed more or less evenly through established brassica crops. Reducing the quantity of ANCS released from the traps either by diluting the concentrate with liquid paraffin or by presenting the concentrate in Wädenswil dispensers reduced the numbers of females caught. There was no indication that ANCS became repellent, even when released at a rate of 24 ml/trap per day. For maximum effectiveness, the ANCS dispenser had to be placed at the centre rather than at the edge of the trap. Attempts to make traps more effective by releasing the ANCS from several point sources around a trap, in the hope that this broader odour plume would ‘ attract ’ more flies, were unsuccessful. The ANCS-baited trap had an effective zone only 5 m in radius.