The size and occurrence of the first brood of adults of Aeneolamia varia saccharina (Dist.) are examined in relation to the pattern of egg eclosion and rainfall. The proportion of eggs hatching within a month of oviposition in the laboratory (short-period eggs) decreased from over 90% in August to less than 20% in January, but the incubation periods of the remaining, long-period eggs were longest in those laid during October and November. The overall hatching distributions tended to be bimodal with most eggs hatching during the early months of the year under moist conditions at 26°C. Dry soil conditions delay eclosion, and eggs obtained from fields during the dry season and then incubated under moist conditions tended to hatch at the normally expected time of the first rains in May. The numbers of eggs expected to produce the first brood, computed from laboratory hatching data and estimates of the numbers and fecundities of froghoppers during the second, third and fourth broods, were less than the actual numbers sampled just before the first rains. There was a close relationship between the first rainfall of over one inch within 48 h and adult emergence 27 and 34 days later, and 85% of field egg populations in May had hatched and/or died by the week after the first rains. However some variation in the date of their occurrence accounted for non-synchrony of first broods over the region. The numbers of diapause eggs in fields sampled during the dry season failed to give a good predictive relationship with first brood adult populations, probably because of density dependent mortality of eggs or hatchling nymphs.

Singapora diversa sp.n. is described from specimens found breeding on Pterocarpus macrocarpus in Thailand, and a key is given to the four known species.

The carob gall midge, previously known as Eumarchalia gennadii (Marchal), is formally assigned to Asphondylia H. Loew, and Eumarchalia Del Guercio is synonymised with Asphondylia. Specimens of Asphondylia reared from pod galls on carob (Ceratonia siliqua) during biological research by G. M. Orphanides in Cyprus seem to be morphologically indistinguishable from specimens reared by him from galls on Capsicum annuum, Capparis spinosa, Urginea maritima, Asphodelus fistulosus, Solanum tuberosum, Hypericum crispum and Sinapis spp. Possible reasons for this unusually wide host range of the carob midge are discussed with particular reference to the occurrence of ambrosia fungi in galls of the genus Asphondylia. Gall midges reared from Verbascum sinuatum in Cyprus are morphologically distinct from A. gennadii and are identified as A. verbasci (Vallot). Characters separating these two species are illustrated and tabulated.

In Cyprus, the pods of the carob tree (Ceratonia siliqua) are infested by three races or sibling species of midges: the pepper, caper and squill midge (Asphondylia spp.). This classification has been made on the basis of secondary host-plant preferences. Tests in cages revealed that secondary host-plants which are attacked by these midges during spring, summer and autumn, taken together, are: pepper (Capsicum annuum), potato (Solanum tuberosum), caper (Capparis spinosa), garden rocket (Eruca sativa), mustard (Sinapis spp.), sea squill (Urginea maritima), asphodel (Asphodelus fistulosus), and St Johnswort (Hypericum crispum). The carob midge complex overwinters as young larvae in carob pods and may have a maximum of six or seven generations per year according to the location. The emergence pattern of the overwintering generation varied between locations. The adult sex ratio was 42 ♂ : 100 ♀ and the mean longevity under laboratory conditions was 55 h. Some major morphological characteristics of all developmental stages are also presented. The larval stage is divided into three instars. Sex identification has been determined at the pupal stage.

Counts of first-instar larvae showed that in a potato plot near Canberra, A.C.T., eggs of Phthorimaea operculella (Zell.) were more prevalent around the bases of plants than between the rows or 2 m outside the plot; the few eggs on the plants were on dead leaves. In small plots each of different plant species, with due allowance for predation, many eggs were laid around tobacco and potato, and few or none near tomato, maize, lettuce or pea. Older larvae were most numerous on tobacco plants, while adults were most numerous on potato plants. A series of laboratory experiments using different oviposition substrates showed that the factors favouring oviposition could be ranked, in descending order: coarse substrate, shade, and treatment of the substrate with juices of potato tubers or foliage; foliage of potato or tobacco was not preferred.

Two strains of Blattella germanica (L.) were developed from a laboratory colony that was resistant to diazinon, propoxur, pyrethrins, lindane and DDT due to selection with diazinon. One strain was reared for nine generations without selection; the other strain was selected with propoxur for 14 generations; selection of the parent strain with diazinon was continued. Resistance to all five insecticides was stable for nine generations in the unselected strain, indicating fixation of the recessive genetic factor for diazinon and propoxur resistance and the incompletely dominant factor(s) for pyrethrins, lindane and DDT resistance. Diazinon and propoxur were equally effective as selecting agents for increasing resistance to diazinon, propoxur and pyrethrins and maintaining resistance to lindane and DDT. Resistance to diazinon and propoxur is probably due to a single recessive factor which attained genetic fixation by selection with diazinon. Cross-resistance to pyrethrins, lindane and DDT, also fixed by diazinon selection, is not due to heterotic effects but may be the pleiotropic action of the diazinon-resistance gene or due to a separate genetic system. The practical implications of this research are discussed.

The larvae of ten species of Ixodid ticks are described, particular emphasis being placed on the setation of the capitulum and palps, and a key is provided to the larvae of 14 species from the eastern Cape Province of South Africa that are common, economically important or difficult to separate. Important characters are illustrated in 62 scanning electron micrographs.

Descriptions are given of the nymphs of five species of ticks from the eastern Cape Province of South Africa, namely Amblyomma marmoreum Koch, A. nuttalli Dönitz, Hyalomma marginatum rufipes Koch, Rhipicephalus evertsi Neumann and Ixodes pilosus Koch. Distinguishing characters are illustrated in 32 scanning electron micrographs.

Pomello and lemon seedlings kept for different time periods in various nutrient solutions were examined for their degree of infestation with Aceria sheldoni (Ewing), the citrus bud mite. Chemical analyses indicated that seedling leaves and buds had a higher nitrogen content in a potassium-free solution, and a lower nitrogen content in a nitrogen-free solution, when compared with their respective contents in a standard solution; in buds these differences were also shown by certain amino acids. Infested seedlings kept in a potassium-free solution had significantly more mites than those kept in a nitrogen-free solution, and the latter had significantly fewer mites than those kept in a standard solution. No increase in mite populations was noted on seedlings kept in high-nitrogen solutions. The relationship between the levels of potassium, nitrogen, magnesium and manganese and the mite population is discussed. No effect on mite reproduction was noted when sodium or calcium was used as a substitute for potassium.

The trend in the relative populations of Oryctes rhinoceros (L.) in two areas of the Gazelle Peninsula, New Britain, was studied by trapping adults searching for breeding sites. In a high rainfall area with 10-year-old palms and many possible breeding sites, there was a large initial population of beetles which declined over the next three years with the gradual disappearance of the breeding sites; weekly catches were higher when the undergrowth in the trapping area was slashed, and to some extent also at new moon; catches were depressed by heavy rain. The ♂/♂ sex ratio was 0·31; all females had mated and had mature eggs in the lower ends of the oviducts. These results were compared with those from a low rainfall area with 70-year-old palms and dispersed breeding sites. Catches were generally lower; they showed no long term trend and were not related to slashing or weekly rainfall, but were inversely related to the number of rainy days per week.

The performance of native and laboratory-bred Glossina morsitans morsitans Westw. was observed in Kariba, Rhodesia, the original natural habitat of the colonised Langford strain. After two years in captivity, the Langford strain was similar to the native strain in survival, dispersal, and rate of recovery in the field. No differences were detected in laboratory studies of the mating behaviour of the two strains. Native-strain males sterilised in the pupal stage with tepa were similar to untreated males in dispersal, survival, and rate of recovery. Also, both the released laboratory-bred flies and the released native strain flies compared favourably with the native population.

Larvicide tests were conducted on five species of mosquitoes, each of which had one or more DDT-resistant strains. The high potencies of DDT and, to a large degree, of DDD were completely lost by resistance. Other compounds were affected in different degrees according to the resistance mechanisms present, as indicated by resistance spectra and the effects of synergists. DDT-resistant strains of Culex pipiens fatigans Wied., Anopheles quadrimaculatus Say and A. stephensi List, showed highly specific resistance to DDT, probably dependent on a dehydrochlorination mechanism. DDT-resistance in Aedes aegypti (L.) and A. gambiae was also high, but there was definite evidence of cross-resistance to biodegradable DDT-analogues (about ×4 and ×10, respectively). This low-level, but definite, cross-resistance extended to a number of other compounds, notably pyrethroids, insect development inhibitors, amines, etc. The presence of synergistic action by piperonyl butoxide suggested that this depended on a microsomal oxidation system.

Isotopically labelled (14C) DDT and malathion were used to study pick-up and penetration of these insecticides by larvae of normal and resistant Ae. aegypti. Both the actual and the percentage penetration of DDT were greater in the resistant than in the normal strain. Whatever the reason for this, it disposes of the possibility of reduced pick-up and penetration as a factor in DDT-resistance. With malathion, the percentage penetration was always higher in the susceptible strain than in the resistant one, though in some cases the actual amount was less.

Field trials were undertaken in Victoria and New South Wales, Australia, to discover whether synthetic sex pheromone, cis-8-dodecenyl acetate, could be used to control the oriental fruit moth, Cydia molesta (Busck), in peach orchards by the disruption technique. When pheromone was released at rates exceeding 5 mg/ha h from polyethylene capillary tubes males were generally unable to locate synthetic pheromone sources or live virgin females. By maintaining a constant rate of release per unit area it was possible to reduce the number of dispensers from one per 50 m2 to one per 400 m2. There was no significant difference in disruption when pheromone was released from tree crowns at 3·5 m or lower down at 1·5 m. Shoot and fruit damage from trials in commercial orchards suggested that pheromone treatments were as effective as a full seasonal schedule of insecticide applications in reducing damage.

The development of an outbreak of the woodwasp, Sirex noctilio F., in a 30-year-old population of Pinus radiata in Tasmania was traced by growth ring analysis of killed trees. The outbreak probably developed from small foci; it reached its peak when the trees were 18–19 years old and then declined rapidly. Attack per tree was directly related to the density of emergents from trees killed in the previous season and the intensity of oviposition drilling was modified by the rainfall during the emergence season; the frequency of treble oviposition drills was directly related to summer rainfall. Survival of insects within trees declined with the years; this was related to the greater vigour and resistance of the surviving trees, but was apparently modified by spring rainfall. Resinosis and polyphenols associated with growth rings in stems living in 1964 indicated an increase in the proportion of trees resisting attack during the outbreak. The growth patterns of attacked and unattacked trees, and the obvious susceptibility of the weaker understorey trees, are discussed and due attention to site quality and plantation management are recommended to reduce Sirex attack in future.

The dispersion and density of brood galleries of the wood-boring ambrosia beetle, Xyleborus fornicatus Eichh., in the tea plant depends on the type of branch (primary, secondary and tertiary) and not on the total available length of branch nor on branch thickness. Within the different branch types, branch lengths and the numbers of galleries contained in them are directly related. Significantly more galleries are formed in the primary branches than in the secondaries, which themselves carry more than the tertiaries. For precise estimation of Xyleborus population density, a stratified sampling system, representing the different branch classes, will be required.

Six trials with an unpurified suspension of Heliothis armigera nuclear polyhedrosis virus (NPV) against Heliothis armigera (Hb.) larvae on sorghum (five trials) and on cotton (one trial) during 1971–73 are described. Commercial preparations of H. zea NPV and of Bacillus thuringiensis were included in two of the trials. H. armigera NPV was as successful as a standard insecticide in preventing losses of sorghum in one trial. Lowering the rate of NPV reduced the control of H. armigera larvae. There was no difference in control achieved by spraying in the morning or in the evening. Spraying every second or every third row (relying on natural spread of the virus) reduced control. Low concentrations of molasses (0·6%) made control by 100 larval equivalents (L.E.) per hectare as good as that by 200 L.E. per hectare without molasses. Neither the commercial H. zea NPV nor the Bacillus preparation was as effective as the local virus. The local virus was reasonably effective against H. armigera on cotton at very high rates and with molasses. It was not as damaging as carbaryl to populations of egg parasites and predators, but the predators did not control damaging populations of aphid and Jassid on the virus-sprayed plots.

Faecal pellet production by Tetranychus cinnabarinus (Boisd.) was recorded at different temperatures (19, 24, 30, 35°C) and relative humidities (0% to 100%); at all temperatures pellet production was greater under dry than under wet conditions. A feeding index based on faecal pellet production and the proportion of adults surviving each day showed that the optimal conditions for the mite were 24°C and 38% r.h. Pellet production increased under continuous light and, under any particular set of conditions, was closely correlated with the numbers of eggs laid. It is concluded that faecal pellet production can be used as a measure of feeding within a given set of conditions provided it is supplemented and checked by other data.

Night-time observations on adults of Heliothis armigera (Hb.), and data from light-trap and hand net catches in irrigated and dryland crops, showed that both sexes flew and fed and females oviposited between 20.00 and 23.00 h. From then until 02.00 h both sexes were inactive, but. from 02.00 to 04.00 h the males flew above the crop in a ‘purposeful’ manner, while the females were stationary and releasing pheromone. During this period of high male and low female activity, copulation in cages, assembly of males to females in cages and copulating pairs on crop plants were all observed. Inseminated female H. armigera were collected in crops which were at a stage suitable for oviposition, while traps away from crops or near mature crops collected mainly virgin females. It is suggested that susceptible crops attract H. armigera adults and that, once within the crop, inseminated females are ‘trapped’ by suitable physiological cues from the plants. Identification of such cues could assist in the breeding of crop varieties resistant to H. armigera attack.