Analysis of published data on catches of insects in light-traps with a variety of light sources and of different designs showed that all conformed to the previously proposed model describing the functioning of a light-trap: catch = constant × where W = trap illumination and I = background illumination. Light-trap catches in differing cloud conditions and in open and woodland situations also varied as predicted by the model. A table of correction factors for different amounts of cloud cover is provided. The results are discussed in relation to use of light-traps and interpretation of light-trap data.

An investigation was carried out into the use of water traps for sampling Glossina morsitans submorsitans Newst. and G. tachinoides Westw. in Yankari Game Reserve in sub-Sudan savanna in northern Nigeria. The traps consisted of coloured trays filled with water plus small quantities of formalin and detergent. Colour was thought to be the major factor attracting flies to the traps, white traps being most effective for G. m. submorsitans and black ones for G. tachinoides. Water traps were compared with biconical traps, and both methods showed similar changes in catches in different vegetation types over a year. Males and females of both species showed a marked expansion in distribution in the rains and a contraction to riverine woodland in the dry season, though females of G. m. submorsitans could be caught in the adverse deciduous woodland and open savanna all year round. Water traps are considered a very cheap and practicable sampling method for ecological studies on these species of Glossina, providing specimens well preserved upon capture for later morphometric and analytical studies.

In the laboratory, the trail pheromone methyl 4-methylpyrrole-2-carboxylate (M4MP2C) when added to bait particles acts as an attractant to leaf-cutting ants, increasing the pick-up of pheromone-impregnated bait compared with plain bait. However, field trials in Trinidad, Brazil and Paraguay were disappointing. Bait with and without pheromone was scattered in the foraging area, and the proportion of each taken to the nest by Atta sexdens rubropilosa Forel, A. cephalotes (L.) and Acromyrmex octospinosus (Reich) was assessed. In only one of the experiments (A. octospinosus foraging bait with 50 p.p.m. of M4MP2C) was increased pick-up detected. Four reasons for this are suggested: (1) small pheromone effects are difficult to measure as scattering bait produced a patchy distribution and heterogeneous replicates, whilst choice trials on plain and pheromone-impregnated bait placed close together were difficult to interpret, as the pheromone probably excited the ants, increasing pick-up of plain bait; (2) A. octospinosus workers, the subject of detailed studies, were less sensitive to M4MP2C in the field than in the laboratory; (3) as the pheromone only attracts, it does not produce a comparable increase in the number of pieces picked up, contact/pick-up ratios of sucroseimpregnated discs increasing from 2·26 at 5 pg pheromone to 16·39 at 50 ng; and (4) soyabean oil, citrus-pulp extract and orange juice were found to be attractive, and when pheromone was added, its effects were not additive. Early studies used sucrose-impregnated paper discs, and as these have no attractants of their own, the addition of M4MP2C had a more marked effect. It is concluded that M4MP2C is not a cost-effective addition to current leaf-cutting ant baits which possess food odours, a much cheaper source of attractiveness.

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.

Based on the results of field surveys carried out between May 1977 and June 1981, the distributions of Glossina morsitans submorsitans Newst., G. palpalis gambiensis Vanderplank and G. tachinoides Westw. in Mali are presented and compared with previously reported information. The distributions of both G. m. submorsitans and G. p. gambiensis were found to be greater than previously reported, whereas that of G. tachinoides was found to be less. The apparent northern limits of both G. m. submorsitans and G. p. gambiensis are at approximately 14°20′N but that of G. tachinoides is at only about 13°10′N. No specimens of G. longipalpis Wied., previously reported from Mali, were captured.

Behavioural responses of Triatoma infestans (Klug) to visual stimuli were analysed using a novel method involving remote monitoring of individual tethered bugs. T. infestans showed negative phototactic behaviour and a reduction in activity in response to a directional white light stimulus at an intensity of 1·2 /µW/cm2. A lower intensity of white light (0·6 µW/cm2) elicited a similar negative phototaxis but failed to induce a significant reduction in activity. The response to green light at 0·6 µW/cm2 was similar to that towards white light at 1·2 µW/cm2. Blue light did not induce any behavioural responses, whereas red light induced a significant reduction in activity at the lower intensity but did not affect phototaxis. Infrared radiation did not induce any significant behavioural effects, but there was an indication that T. infestans can detect near infrared radiation (750 nm). The activity response to the higher intensity white light appeared to be mediated primarily by the compound eyes. The dorsal ocelli, however, were involved in the directing of the phototactic response. T. infestans responded to moving objects by a marked reduction in activity. Slowly moving objects induced a following response, whereas more quickly moving objects did not.

Chromolaena odorata is a tropical American species of the Compositae that has become a serious problem in plantations in the tropics of Asia and Africa. The history of attempts to control it using the arctiid moth Pareuchaetes pseudoinsulata Rego Barros (misidentified in previous literature as Ammalo insulata (Wlk.)) is summarised. The taxonomy and distributions of the five species in Pareuchaetes are presented, together with keys based on genitalic characters, three new synonyms and one new combination. Information on the biogeography and ecology of the Pareuchaetes species is used to assess their potential as biological control agents.

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.

Extracts from cultures of Pseudomonas aeruginosa, Bacillus subtilis, Proteus mirabilis and Enterobacter cloacae in samples of fleeces from sheep were incorporated into nutrient agar and exposed to females of Lucilia cuprina (Wied.) in cages. The blowflies often laid eggs in response to the odours emanating from the cultures of all bacteria. Pseudomonas aeruginosa and E. cloacae did not appear to utilise fleece components in the production of oviposition stimulants, whereas B. subtilis did, utilising compounds such as palmitic acid, and Proteus mirabilis degraded wool fibres to produce sulphurous compounds. The results are discussed in relation to the role of L. cuprina in cutaneous myiasis of sheep.

Bracon ?hancocki (Wlkn.) is a larval ectoparasite of Cydia ptychora (Meyr.), a major pest of cowpea at Ile-Ife, Nigeria. Parasitism occurred in the field all the year round, varying from 0 to 65·9% and with the highest incidence from September to February. In the laboratory, the fecundity of the parasite was low, averaging about six eggs per female. The life-cycle was completed in ten days. Mating occurred soon after emergence, and the preoviposition period lasted about 2–3 days. Unmated females rarely laid eggs, and their life-span averaged six days as compared to 14 days for mated females. The female:male ratio was 2:1. The parasite rarely attacked previously paralysed hosts, and the preferred hosts were the older, larger larvae. A description of the egg and larvae is given.

Ollarianus balli (Van D.), a leafhopper vector of disease-associated mycoplasma-like organisms, was found to be rare in Jamaica. Its distribution and frequency were governed primarily by the distribution and density of its specific field host, the wild legume Rhynchosia minima on which it completes its life-cycle. Under suitable temperature conditions, O. balli was easily reared in captivity on R. minima and pigeon pea (Cajanus cajan), although the latter is not a natural host. It oviposited into the hypodermal tissues covering veins of sterns, petioles and the abaxial surfaces of older leaves. Eggs hatched 10–15 days after oviposition and there were five nymphal instars. Instar 1 was distinct from instars 2–5 which, except for size, were similar in appearance. The first adults matured some three weeks after the final moult. There appeared to be little difference in the average life-span of males and females of O. balli.

Pre-treatment of females of Lucilia cuprina (Wied.) with the synergist piperonyl butoxide increased the resistance factors of an organophosphorus-resistant strain Q to four organophosphates in comparison to the susceptible strain LS. However, pre-treatment with S,S,S-tributylphosphorothrithioate (TBPT) reduced the resistance factors of Q to three organophosphorus insecticides. As TBPT is an esterase inhibitor, it is suggested that esterases contribute to resistance in the Q strain. Resistance to diazinon in the Q strain is due to a single, partially-dominant gene on chromosome 4. By the use of the backcross and discriminating dose technique, resistance to parathion, fenitrothion, chlorfenvinphos and fenitro-oxon (dimethyl 3-methyl-4-nitrophenyl phosphate) (the latter two were synergised by piperonyl butoxide to obtain a genetically discriminating dose) was also shown to be controlled by a single, partially-dominant gene on chromosome 4. It is concluded that this gene confers resistance to organophosphorus compounds in L. cuprina, probably by providing an esterase with enhanced ability to degrade organophosphates.

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.

Data from surveys in 1951, 1972, 1973 and 1978–79 showed that tick numbers are generally low on the miniature breed of cattle in the Yemen Arab Republic and tick-borne diseases have not been recognised as a serious problem. This breed should be investigated for properties of resistance to tick bite. Each tick species commonly infesting livestock has been recorded as transmitting viruses (and some also rickettsiae) causing human illness in Africa and/or Eurasia. Between 1300 and 2000 m in altitude, Amblyomma variegatum (F.) is more abundant on camels than on cattle and Boophilus annulatus (Say) infests cattle. Below 1500 m, B. kohlsi Hoogst. & Kaiser is more abundant on goats than on sheep. Haemaphysails sulcata C. & F. infests sheep in certain highland areas. Hyalomma dromedarii Koch is the most prevalent and abundant tick of livestock. H. anatolicum excavatum Koch is next in abundance on camels. The numbers of H. anatolicum anatolicum Koch vary greatly in collections from different years. Few examples of H. erythraeum Tonelli-Rondelli were taken. H. impeltatum Schultze & Schlottke and H. marginatum rufipes Koch are widely distributed; the former is most abundant in coastal lowlands, the latter in humid habitats. H. arabica Pegram, Hoogst. & Wassef is recorded from goats, and also sheep, in southern hills. Immature examples of Hyalomma spp. are especially abundant on camels and hares. Rhipicephalus evertsi evertsi Neum. is common in the highlands, as is R. simus Koch below 2000 m. Species of the R. sanguineus (Latr.) group occur on some livestock.

Flight activity characteristics of Chortoicetes terminifera (Wlk.) were recorded in adults suspended on a simple flight balance in a wind tunnel. Ninety-one per cent, of flights by post-teneral (>5-day-old) insects lasted less than 60 s, and only 11% of adults flew for a full 20-min test period at 30°C. The flight capacity ranged from a few or many short flights to continuous flights. Females flew for a greater proportion of the time than males. Flight activity increased with food-deprivation, and only fully hardened (>9-day-old) insects flew continuously throughout a 45-min test period at 26–41°C. Gravid females also made long flights. The frequencies of flight durations by laboratory-reared insects were strikingly similar to the day flight of milling field populations in eastern Australia. Flight performance observations indicated that lift declines with time in flight, wing-beat frequency initially being 33·2 Hz in males and 30·0 Hz in females. The results are discussed in relation to field studies.

Studies were carried out in Nigeria on oviposition and the deadhearts caused by Diopsis macrophthalma Dalm. on ten rice varieties. The varieties were divided into three groups according to the numbers of eggs recorded on them. Strong positive correlations existed between (a) the numbers of eggs and tillers, (b) the numbers of eggs and deadhearts, and (c) the numbers of deadhearts and tillers. Some varieties compensated for damage by the production of new tillers. In the variety Suakoko 8, most of the eggs were confined to the leaf blades in young plants and to the leaf sheaths as the plants grew older. Peak oviposition occurred 30–40 days after transplanting. Some implications of the results for a pest management programme are discussed.

Adults of a field strain of Blattella germanica (L.) resistant to dieldrin and bendiocarb were used to evaluate two insecticide bait formulations, 50% boric acid plus 50% porridge oats and 0·25% iodofenphos gel in comparison with gel alone and culture food. All cockroaches from the boric acid plus oats treatment died in less than 20 days, whereas some that fed on iodofenphos gel, culture food or gel blank survived for 30 days. Both insecticides caused females to drop their oothecae prematurely, and fewer eggs from the boric acid plus oats treatments hatched. More cockroaches exposed to boric acid plus oats bait died outside the harbourages than those from the iodofenphos gel treatments. Boric acid plus oats or iodofenphos gel offered together with culture food were eaten throughout the treatments. With iodofenphos gel alone, no bait was eaten after four days, but mortality continued for 21 days. The minimum amount of insecticide bait required to kill all 100 cockroaches was about 1340 mg iodofenphos gel, and 100·0 mg boric acid plus oats. After exposure for 24 h, all cockroaches died within nine days after exposure to boric acid plus oats, whereas with iodofenphos gel some survived after 21 days. Two further applications of gel bait in the iodofenphos experiments on days 13 and 17 failed to increase mortality although some bait was eaten. B. germanica was killed more quickly by both insecticide baits when deprived of drinking water.

Exposure of pregnant females of Glossina morsitans morsitans Westw. to a standard dose of 14·8 ng/fly of endosulfan confirmed that they acquire a higher level of tolerance of this insecticide than young unmated females. The development of tolerance was rapid, from threefold 48 h after larviposition, to eightfold midway through the pregnancy cycle at 4–5 days, and reaching 10- to 14-fold 24–28 h before the next larviposition. The acquisition of substantial tolerance preceded the periods of major growth of the larva in utero and of the developing oocyte, and it is suggested that the development of tolerance is associated with the diversion of insecticide by partitioning into lipid components of the milk as they are synthesised. The level of tolerance attained at equivalent stages of the pregnancy cycle appeared to be largely independent of the age of the fly between the second and fifth cycles, but that reached in the first cycle was lower. Some females survived repeated exposure to endosulfan in successive cycles. The offspring of treated females showed no apparent effects until shortly after adult eclosion, when substantial but variable delayed mortality occurred. However, surviving females and their offspring continued to reproduce normally. It is concluded that tolerance of the insecticide in pregnant flies accounts adequately for the observed survival following non-residual applications of endosulfan, and strategies for preventing this survival, and achieving eradication, are discussed.

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.