A critical review is presented of the many and varied procedures for sampling adult mosquitoes. All sampling methods are subject to bias, but human-bait collections are probably the most reliable single method for detecting and monitoring populations of anthropophilic species. The estimation of realistic man-biting rates, however, remains difficult. The recent advances in computer technology have generated considerable interest in population modelling, with the aim of getting a better insight into the complexities of population dynamics, mosquito control and disease transmission. Although such approaches may be informative, it is stressed that models should be based on meaningful values of the critical parameters and that these are best obtained from field populations. The difficulties of interpreting mosquito collections in both attractant traps, such as animal-baited traps, carbon-dioxide-baited traps and light-traps, and in non-attractant ones, such as Malaise traps, sticky traps, ramp traps, rotary traps, suction traps and vehicle-mounted traps, are described. Suction traps probably provide the least biased catches of aerial populations of mosquitoes, but, if populations as a whole are to be considered, then resting adults also must be adequately sampled, and this may prove difficult. It is emphasised that different trapping techniques usually sample different components of a population, and that the choice of sampling methods depends much on the type and quality of information required. The limitations of using mark-recapture techniques to study adult dispersal and obtain absolute population estimates are discussed, together with the advantages and disadvantages of applying simple and more complex mathematical procedures for analysing recapture data.

Field and laboratory studies at Ibadan, Nigeria, showed that the young nymphs of Zonocerus variegatus (L.) normally reject cassava after biting it and die if they are confined on growing leaves. Later instars will eat cassava, especially when deprived of food for some time, but the adults progressively lose weight when restricted to feeding on growing cassava. On cut cassava, on the other hand, extensive feeding occurs and normal growth is maintained. The change from unpalatability to acceptability occurs within about an hour of cutting and is apparently associated with wilting. Cassava produces latex, but this was not distasteful to Zonocerus. The readiness to feed on growing cassava was associated with low levels of hydrogen cyanide production by the leaves; wilted leaves still produced hydrogen cyanide, but at a lower rate than turgid, growing leaves. In the area around Ibadan, Zonocerus regularly defoliates cassava in the latter part of the dry season, probably because a shortage of attractive foods forces the insect to eat cassava.

The female sex pheromones of Chilo suppressalis (Wlk.) were previously identified as (Z)-11-hexadecenal and (Z)-13-octadecenal. This paper describes field trials of the synthetic pheromones carried out in the Philippines, Korea and Iran during 1975 and 1976. These trials established that the two pheromones in their naturally occurring ratio are attractive to male C. suppressalis in the field. Both pheromones are necessary for efficient attraction, and ratios of the two pheromones close to the naturally occurring ratio are the most attractive. The rate of release of the pheromones was found to be critical in order to obtain an attractant source comparable with the virgin female moth. The bisulphite adducts of the pheromones showed some promise as a slow-release source of attractant material with a long field life.

Preliminary experiments were carried out to assess the potential use of the two natural pheromones and of two pheromone “mimics”. (Z)-9-tetradecenyl formate and (Z)-11-hexadecenyl formate, as mating disruptants. All four compounds were shown to interfere with pheromonal communication between the sexes

The genitalia and reproductive organs of a normal and of an abnormal type of cabbage root fly (Delia brassicae (Wied.)) are described. The abnormal type, possessing incomplete genitalia, was found in the Welles-bourne laboratory culture. The abnormal females were sexually attractive to males but were unable to copulate or lay eggs, whereas the abnormal males copulated but did not inseminate females. The age of females at oviposition and both larval and adult diets influenced the number of abnormal flies in subsequent generations.

Mature, singing adults of the bush crickets Platycleis intermedia (Serv.) and P. affinis Fieb. are normally separated in the field through differences in habitat preference. At some localities in southern France, nymphs and young adults of the two species occurred mixed together in herbaceous vegetation surrounding barley fields. Occasionally, there was acoustic interference between them, with modification of the song of P. intermedia. This was overcome by P. intermedia moving into the bushes and P. affinis into the barley. Cutting of the barley resulted in an invasion of the P. intermedia habitat by P. affinis so that there was further interspecific acoustic interference. Sheep grazing caused vegetation mosaics, which again created the conditions for acoustic interaction between the two species.

Of 11 chemosterilants tested on adult males of Ephestia kuehniella Zell., only tepa induced complete sterility. It also induced complete sterility in females of E. kuehniella. Hempa showed weak sterilising activity against adult males and had no sterility effect against the females, even at dose levels that induced high mortality. Cycloheximide induced slight sterility in the males. Carbaryl was inactive as a sterilising agent but induced some of the males to produce spermatophore sacs without mating. The latter effect was also induced in a few males by injection of tri-, penta- or hexamethylmelamines, which also induced significant infertility in eggs of untreated females mated with treated males. No structure-activity relationship existed in this group of compounds. Hemel also induced two mating aberrations: permanent copulation and sterile mating. A juvenile hormone analogue (a mixture of 3 hydrochlorinated farnesoates with activity about 1% of that of natural juvenile hormone) induced significant sterility in adult females of E. kuehniella when applied topically. It also caused 38–41% reduction in oviposition at 50–80 μg/adult. However, at 100 μg/adult, the analogue completely inhibited mating in the females. Injected doses of melatonin also caused significant reduction in oviposition. At 5·3 μg/adult, it induced most of the eggs laid to undergo incomplete development. The effects of these compounds are discussed. The sterility indices of tepa against adult male and female E. kuehniella were 19·5 and 9·2, respectively; that for hemel against males was 1·4.