The effects of DDT on the behaviour and mortality of Anopheles gambiae Giles, A. funestus Giles, Mansonia uniformis (Theo.) and Culex pipiens fatigans Wied., entering experimental huts, have been studied with the assistance of gas-chromatographic techniques.

Sixty to 70% of A. gambiae and 70–80% of M. uniformis were deterred from entering verandah-trap huts treated indoors with a nominal dosage of 200 μg/cm2 of DDT active ingredient. Gas chromatographic techniques indicate that the chemical basis of the deterrency was a steadily diminishing outflow of DDT from the hut, either as a dust or vapour, and the build-up of deposit on the untreated overhanging eaves to 0·02 to 0·27 μg/cm2 seven months after treatment. A. funestus was less deterred than A. gambiae and M. uniformis, but the behaviour of C. p. fatigans was almost unaffected by the DDT deposit.

Overall mortalities were highest in A. funestus and M. uniformis, lower in A. gambiae and extremely low in C. p. fatigans.

There was a marked irritant effect of the DDT deposit on recently blood-fed A. gambiae, some 50–70% being driven out of the treated huts. This behaviour occurred to a lesser degree in A. funestus but was absent in M. uniformis and C. p. fatigans. The chemical basis of the irritant effect was indicated to the extent that surviving mosquitoes, that left the treated hut, showed 1·5 ng/insect of DDT. Mosquitoes that died, whether indoors or after leaving the hut, picked up amounts ranging from 7 to 20 ng/insect.

A pilot field study, involving periodic augmentative release of predatory larvae of a dragonfly, Crocothemis servilia (Drury), to suppress a mosquito, Aedes aegypti (Linnaeus), was conducted during the rainy season in Yangon (Rangoon). More than 90% of pre-adult A. aegypti occurred in domestic water-storage containers. Evaluations of larval and adult numbers of A. aegypti were made half-monthly three times before, and seven times after, treatment began. Four laboratory-reared, three-week-old C. servilia larvae were placed in each major source of A. aegypti larvae immediately after the third evaluation and then monthly for three successive months. Such treatment reduced the larval population of A. aegypti to a very low level in two to three weeks and suppressed it progressively until the trial ended; the adult population was greatly reduced after about six weeks and was progressively diminished thereafter until the trial ended. The trial's success was ascribed to: the virtual confinement of pre-adult stages of the target mosquito to containers accessible to control operators; the behaviour, growth rate, survival and ready availability of the chosen species of dragonfly; and the awareness and enthusiastic participation of local householders.

PCR-based techniques to investigate predator-prey trophic interactions are starting to be used more widely, but factors affecting DNA decay in predator guts are still poorly understood. Here, we investigated the effects of time since feeding, temperature and amplicon size on the detectability of prey DNA in the gut content of two closely related predator species. Cereal aphids, Sitobion avenae, were fed to the carabid beetles Pterostichus melanarius and Nebria brevicollis. Beetles were allowed to digest their meal at 12°C, 16°C and 20°C, and batches of beetles were subsequently frozen at time periods from 0–72 h after feeding. Aphid DNA was detected within beetles' gut contents using primers amplifying fragments of 85, 231, 317 and 383 bp. Prey DNA detection rates were significantly higher in N. brevicollis than in P. melanarius, indicating fundamental dissimilarities in prey digestion capacities. High temperatures (20°C) and large amplicons (383 bp) significantly decreased detection rates. The shortest amplicon gave the highest prey DNA detection success, whereas no differences were observed between the 231 bp and the 317 bp fragment. Our results indicate that factors such as ambient temperature, predator taxon and amplicon size should all be considered when interpreting data derived from PCR-based prey detection. Correction for such factors should make calculation of predation rates in the field more accurate and could help us to estimate when predation events occur in the field.

Temperature tolerance was investigated in nine populations of Plutella xylostellaLinnaeus from tropical and temperate regions of Asia. At all rearing temperatures between 15 and 35°C, no clear differences were observed in female egg production or larval development between tropical and temperate populations. Thus, tropical populations did not show a high-temperature tolerance superior to that of the temperate populations. In all populations, the net reproductive rate (number of new females born per female) largely depended on the number of eggs laid per female, and egg production significantly decreased with increasing temperature (P < 0.001). Larval developmental rate also showed a significant positive correlation with temperature (P < 0.001). Per cent hatch of eggs and larval survival did not show a significant correlation with temperature: hatching was constant between 15 and 32.5°C, but considerably lower at 35°C. Larval survival was similar between 15 and 30°C, appreciably lower at 32.5°C and declined to 0% at 35°C. Based on these results, environmental conditions under which P. xylostella can maintain a high population density throughout the year in tropical and subtropical regions are discussed.

Life table studies of Mussidia nigrivenella Ragonot, a pest of maize in Benin, showed that host plant species had a significant effect on larval survival and developmental time. The maximum percentage of larvae surviving was recorded on jackbean, Canavalia ensiformis (36%) and lowest on maize (18%). Mean developmental time for larvae was longest on maize (19.8 days) and shortest on jackbean (17.2 days). The number of eggs laid was highest for females from larvae fed on jackbean (x– = 176), followed by velvetbean, Mucuna pruriens(x– = 143), and lowest for females where larvae had fed on maize (x–= 127). Longevity of ovipositing females was higher on jackbean (5.4 days) than of those from any other host plants. According to the growth index and life table statistics, jackbean was the most suitable host plant, followed by velvetbean, and maize, the least suitable. Thus, jackbeans should be recommended for use in mass rearing programmes of M.nigrivenella, e.g. as a host for parasitoids in future biological control programmes. Because of the high suitability of jack- and velvetbeans for M.nigrivenella, planting of these increasingly important cover crops should be timed in such a manner that the emergence of female moths from mature pods does not coincide with maize plants in a suitable developmental stage for oviposition and development of young M. nigrivenella larvae.

Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is an invasive citrus pest in southern California, which secretes honeydew and has the potential to spread a lethal bacterial disease, huanglongbing, of citrus. In urban citrus, Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), also an invasive pest, tends honeydew-producing hemipterans. We used field data to determine whether the mutualistic relationship between L. humile and six established species of honeydew producers may hinder or favor the establishment of D. citri and its biological control with Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae) in citrus via competition or mutualism for ants, respectively. In the field, L. humile and D. citri are engaged in a mutualistic relationship. Ants harvest solid honeydew secreted by psyllid nymphs and tended more than 55% of observed D. citri colonies. Linepithema humile displayed a preference hierarchy when tending honeydew producers infesting citrus. It responded equally or less intensively to D. citri than to other honeydew-producing species. Consequently, the mutualism between L. humile and D. citri was affected by the presence of other honeydew-producing species, and the percentage of D. citri colonies tended by L. humile. The number of ants per D. citri colony also decreased as the number of other honeydew producers increased. Diaphorina citri density was also affected by the presence of other honeydew producers. Both colony size and the number of D. citri nymphs counted per tree decreased as the number of other honeydew producers increased. Our results indicate that competition between honeydew producers for the mutualist ant L. humile may hinder the establishment of D. citri by possibly facilitating increased biological control.

Nocturnally active mosquitoes are attracted visually to large (1·5 × 2·4 m) unpainted plywood suction traps. Such traps, which discharge air horizontally in one direction only, were placed in an open field in Florida in various patterns to study the flight behaviour of mosquitoes. When four traps were placed 15 m apart in a column, the two end traps captured 83 or 53% more mosquitoes than the two inner traps, depending upon whether the air discharged from the traps was perpendicular to, or in line with, the trap column. When the traps were spaced 30 m apart, the end traps captured only 13% more than the inner traps, indicating that at this distance visual competition between traps was small. When 16 suction traps were spaced 15 m apart in a grid of four columns of four traps each, the traps at the four corners of the grid captured about 2·1 times, and traps between the corner traps along the edge of the grid 1·5 times, as many mosquitoes of most species as traps within the grid. Subsequently, four additional traps were placed 15 m beyond the corner traps, and these traps captured 3·3 times as many mosquitoes as traps inside the grid. Traps within the grid had four adjacent traps while traps at the edge, corner, and beyond the corner had three, two and one adjacent traps, respectively. The numbers captured by a trap at a particular location in the grid were inversely related to the number of adjacent traps, viz., suction-trap catches were decreased by about 33% as the number of adjacent traps were increased and thus each trap acted as a competing visual attractant on nearby traps. It was estimated that an isolated suction trap would capture approximately five times as many mosquitoes as a trap inside the grid. Assuming these differences between trap collections were caused by the distance at which mosquitoes respond to the traps and thus would be proportional to the visually unobstructed area about each trap, it was calculated that most adults responded visually to the traps from distances of approximately 15·5 to 19 m. Aedes vexans (Mg.) and Psorophora columbiae (D. & K.) were most responsive, followed by Culex nigripalpus Theo. and Culiseta melanura (Coq.) and then by Anopheles crucians Wied., P. ciliata (F.) and Uranotaenia lowii Theo. Only U. sapphirina (O.S.) and Culex quinquefasciatus Say appeared to possess visual ranges of 7.5 m or less. Visually conspicuous objects can serve as long-distance attractants. Low air velocities caused appreciable reductions in trap collections. At a distance of 15 m, the velocity of air discharged from the traps was only 0·6 m/s, but catches from a trap downstream of an adjacent trap were reduced by 17%. Catches from rows of traps downstream from one, two or three rows of traps were reduced by 15, 36, and 51%, respectively. Estimates of mosquito population densities in a natural environment will be affected by the differing visual attractiveness of objects of irregular distribution and sizes and their effect upon wind velocities.

A method for the routine quantitative estimation of mealybug populations on cacao trees is described and the results obtained from 24 successive monthly samples are tabulated.

The quantitative results obtained are of such variability that only gross differences in population density are shown as statistically significant.

From a series of analyses based on the survey data the following conclusions have been reached with regard to P. njalensis, the most important mealybug vector of swollen shoot virus :—

(a) The species is almost invariably attended in the field by Crematogasterine ants, the most important ant species building protective carton tents over the mealybug colonies.

(b) Crematogaster density is closely correlated with mealybug density and the ants construct their carton tents in relation to the numbers of mealybugs to be protected. Some of the arboreal Crematogasterine groups investigated are shown to be consistently associated with higher mealybug populations, and to have a more advanced tent building habit, than others.

(c) Tree to tree variation in mealybug density is shown to be largely dependent on the identity of the dominant ant group.

(d) No direct correlation is apparent between mealybug density and incidence of swollen shoot though populations in areas devastated by virus are usually smaller than in areas in which virus is actively spreading.

(e) The factors of importance in the natural control of P. njalensis populations have been discussed in some detail. It is clear that the species is maintained by ant protection at a density level considerably above that prevailing amongst closely related pseudococcid species which are not ant attended to the same extent. At this level of “ protected steady density ” balance is maintained partly by losses during crop harvesting, and partly by swollen shoot rendering the host plants unsuitable as feeding stations. It is concluded, however, that natural enemies must, in the last analysis, be responsible for maintaining balance.

(f) Since the protected density of P. njalensis is a direct result of ant associations it follows that factors tending to control the attendant ant species will have a delayed effect on mealybug density. In this respect it is believed that Oecophylla, which is strongly negatively correlated with Crematogaster spp., is of importance. Any attempts that may in the future be made to control the mealybugs by killing the ants will have to be designed as specific against the Crematogasterini and non-lethal to Oecophylla and the other large predatory ants common on cacao.

The taxonomy of the Oriental species of Helopeltis is revised and a review of the economic literature is given. An identification key is provided for the 14 recognized species, one of which, H. sulawesi, is described as new. A diagnosis and brief description is given for each species, as well as illustrations of useful taxonomic characters, information on distributions and host records, and a discussion of any known or suspected misidentifications. Lectotype designations are made for 13 nominal species and the following new synonymies are established: H. bradyi Waterhouse = H. ceylonensis De Silva, syn. n and H. romundei Waterhouse, syn. n;H. cinchonae Mann = H. brevicornis Poppius, syn. n.;H. clavifer (Walker) = H. australiae Kirkaldy, syn. n and H. niger Walker, syn. n;H. cuneata Distant = H. elegans Poppius, syn. n;H. fasciaticollis Poppius = H. pallidus Poppius, syn. n and H. pallidiceps Poppius, syn. n;H. theivora Waterhouse = H. oryx Distant, syn. n The somewhat obscure synonymy of H. theobromae Miller under H. theivora is confirmed. Two subgenera are recognized and diagnosed: Afropeltissubgen. n (type species Eucerocoris westwoodi White), including all African species of the genus, and Helopeltis sensu stricto, containing the Oriental and Australasian species.

The present world distribution of six species of Cryptolestes found in stored produce is delineated from the evidence of specimens collected from a small number of countries and from specimens collected from produce examined in ships at British ports.

It is concluded that C. ferrugineus (Steph.) is worldwide, being found in temperate and tropical areas and in humid and dry zones. The range of C. minutus (Ol.) is limited by low temperature and low humidity but it is more abundant than C. ferrugineus in the wet tropics. C. pusilloides (Steel & Howe) is at present confined to the southern hemisphere but may be spreading slowly. It seems unlikely that this species entered stored products handled by the shipping trade much before 1944. C. turcicus (Grouv.) has been identified from Europe, North and tropical Africa, Turkey, North America, Uruguay and Argentina, and C. spartii (Curt.) only from Europe, North Africa and Turkey. C. ugandae Steel & Howe is rare, being found only from Uganda, Nigeria and Ghana.

A methodology is presented to facilitate a declaration that an area is ‘pest-free’ following an eradication campaign against an insect pest. This involves probability models to assess null trapping results and also growth models to help verify, following a waiting period, that pests were not present when control was stopped. Two probability models are developed to calculate the probability of negative trapping results if in fact insects were present. If this probability is sufficiently low, then the hypothesis that insects are present is rejected. The models depend on knowledge of the efficiency and the area of attractiveness of the traps. To verify the results of the probability model, a waiting period is required to see if a rebound occurs. If an incipient but non-detectable population remains after control measures are discontinued, then a rebound should occur. Using a growth model, the rate of increase of an insect population is examined starting from one gravid female or one male and a female. An example is given for tsetse in which both means and confidence limits are calculated for a period of 24 reproductive periods after control is terminated. If no rebound is detected, then a declaration of eradication can be made.

The impact of predation by the generalist carabid beetle Pterostichus melanarius (Illiger) on populations of the field slug Deroceras reticulatum (Müller), and the effects of prey size on the predator–prey interaction, were measured under semi-field conditions. It was hypothesized that environmental heterogeneity would lead to very different patterns of comparative mortality than might be deduced from size choice experiments conducted in the laboratory. Results from outdoor mini-plots, emulating conditions in a field of wheat, demonstrated that P. melanarius significantly reduced numbers of slugs from all size classes, with no apparent preferences. This was in marked contrast to results from earlier laboratory studies, where this beetle fed preferentially on the smallest slugs. The slugs in the mini-plots ranged in size from 2–100 mg and the numbers in the mini-plot reflected the size frequency distribution in the field. Beetles in mini-plots containing high densities of slugs increased significantly in weight, in contrast to beetles in mini-plots with low slug density or no added slugs, which did not. Enzyme-linked immunosorbent assays (ELISA), using anti-slug monoclonal antibodies, showed that where there was a higher density of slugs there was more slug protein in the guts of the beetles. It was concluded that environmental heterogeneity probably provided a greater number and diversity of refugia for smaller than for larger slugs, counteracting laboratory-measured size preferences measured in arenas without refugia. These results have implications for a range of ecological studies involving inter- and intra-specific prey size choice, and emphasize the dangers of extrapolating from the laboratory to the field.

Adult females of Panolis flammea (Denis & Schiffermüller) in the laboratory laid more eggs on some provenances of lodgepole pine (Pinus contorta) than on others, even when offered no choice. Their preoviposition period was inversely related to the suitability of the host for larval growth and development. The shorter the preoviposition period the greater the number of eggs that were laid. Delayed mating resulted in reduced fecundity and reduced egg fertility. Female moths lived longest on those hosts on which they oviposited most. Oviposition preferences were correlated with the ratio of the two monoterpenes α- and β-pinene within the host-plants. The effects of provenance, delayed mating and adult mortality were demonstrated through a simulation model; the effect of delayed mating was particularly marked when adult survival was poor. Egg production in the field in Scotland varied from 30 to 123 eggs per female, but this variation could largely be explained by spring temperature. It was concluded that this relationship was due to the influence of temperature on mating and egg laying. The relationship between temperature and egg production forms a basis for predicting damaging levels of Panolis flammea from either pupal or adult numbers. The effects of provenance and delayed mating demonstrate that the frequency of P. flammea outbreaks in the UK may be reduced by the planting of less preferred lodgepole pine provenances and by mating-disruption methods.

In eastern Africa between 1951 and 1955 and in south-western Morocco in 1960, orientations and densities of flying locusts in migrating swarms of Schistocerca gregaria Forsk. were recorded photographically, with supplementary visual observations. The densities ranged from 0·0006 to 1·23 locusts/m3 (mean spacing between nearest locusts 12 and 1 m, respectively) with a median value of 0·024 locusts/m3; in 50% of the samples mean spacing was 2–4 m, suggesting a preferred distance of that order. The orientations were affected by gregarious reactions to neighbouring fliers, and to locusts in a mass. In the swarms there was a preponderance of streaming groups in which locusts headed in the same general direction; in about half of these groups the angular deviation about the mean orientation was only ±20°. In comparatively dense swarms the orientations of the lower fliers in the interiors of swarms were diverse and random in relation to wind and to the swarm track. But at the leading, the trailing and the lateral edges they were predominantly into the swarm, as the result of observed changes of headings back towards the swarm in locusts flying out beyond the main mass. The orientations of locusts photographed at about 100 m and 200–400 m above the ground were found to be predominantly in the direction of the swarm track, i.e., with wind; it is suggested that they arose from compensatory optomotor responses to retinal velocities of substrate patterns, and are consistent with Kennedy's hypothesis of optomotor orientation to wind. Among lower-flying locusts such responses appeared to become important in diffuse formations and in strong winds. Thus flight on consistently into-wind courses was repeatedly seen in low-flying diffuse formations of sexually mature locusts migrating in light winds. In stronger winds the orientations of lower fliers in all types of swarms suggested responses to unacceptable retinal velocities, which interfered with the into-the-swarm orientations on the swarm edges; the continued cohesion of swarms may thus require a wind profile in which they are not evoked below a certain level. In persistent strong wind in excess of locusts' air speeds, flight activity was reduced, and swarms exhibited low into-wind flight by locusts in small numbers. It is suggested that the characteristic downwind tracks of discrete immature swarms are set primarily by the downwind orientations of their higherflying members. In sexually mature swarms the downwind displacements are probably performed mainly by the denser and the higher-rising swarms, while the into-wind flights of low diffuse formations would slow down movement, and could result in limited displacement up-wind.

Nilaparvata lugens Stål, the Brown Planthopper (BPH), is a major pest in rice. The lycosid Pardosa pseudoannulata (Bösenberg & Strand) and the linyphiid Atypena formosana (Oi) are the early dominant predators in irrigated rice. Later, predatory bugs, including the mirid Cyrtorhinus lividipennis Reuter, become dominant. In unsprayed rice, BPH numbers normally remain low. While P. pseudoannulata is known to be a key natural enemy of BPH, the contribution to BPH reduction by the smaller A. formosana is less well known. Due to the size difference, A. formosana may also be an intraguild prey of P. pseudoannulata. To investigate predation on BPH by the two spider species alone, together and in combination with C. lividipennis, two cage experiments were conducted, the first with adult spiders, the second with immature/unmated spiders. In the latter, spiders were introduced with a delay to allow a better establishment of C. lividipennis. In both experiments, BPH numbers were lowest in treatments with more than one predator species present. Intermediate BPH reduction was obtained with P. pseudoannulata followed by A. formosana and C. lividipennis. While P. pseudoannulata can prey upon large nymphs and adult BPH, A. formosana favour early instar BPH, leading to a more even control across instars in treatments with both spider species. Pardosa pseudoannulata numbers increased more with A. formosana or A. formosana and C. lividipennis present. In contrast, P. pseudoannulata reduced A. formosana and C. lividipennis numbers. The presence of C. lividipennis apparently lessened intraguild predation on A. formosana and may be an intraguild prey of A. formosana. Competition for prey may have added to the antagonistic interactions found. From a biological control perspective, the presence of both spiders in early rice is an advantage for the biological control of BPH in rice. In early rice, results show that A. formosana is an important predator of BPH and, like C. lividipennis, can complement control by P. pseudoannulata and serve as intraguild prey for the latter species.

Both Sitobion avenae (Fabricius) and Rhopalosiphum padi (Linnaeus) are the most important pests of wheat in China and usually coexist on the late period of wheat growth. Pirimicarb was introduced into China for wheat aphid control in early 1990s, and differential susceptibilities of Sitobion avenae (Fabricius) and Rhopalosiphum padi (Linnaeus) to pirimicarb have been observed. A bioassay exhibited that Rhopalosiphum padi possessed significantly higher susceptibility to pirimicarb than Sitobion avenae. The addition of synergists DEF, an esterase inhibitor, PBO, a cytochrome P450 monooxygenase inhibitor, and DEM, a glutathione S-transferase inhibitor, resulted in apparent reductions in the differential susceptibilities, suggesting the involvement of the above three detoxification enzymes in the differential susceptibility to pirimicarb between Sitobion avenae and Rhopalosiphum padi. A biochemical analysis showed that the activities of carboxylesterases and glutathione S-transferases were significantly higher in Sitobion avenae than in Rhopalosiphum padi, consistent with the results of synergism. Acetylcholinesterase is the target enzyme of pirimicarb and the sensitivity of acetylcholinesterase to pirimicarb was significantly higher in Rhopalosiphum padi than in Sitobion avenae. The combined results suggest that multiple mechanisms are likely to be responsible for differential susceptibilities to pirimicarb between Sitobion avenae and Rhopalosiphum padi. The results obtained from this study should be helpful in the rational applications of insecticides.

Regression analyses of a long series of light-trap catches at Narrabri, Australia, were used to describe the seasonal dynamics of Helicoverpa armigera (Hübner). The size of the second generation was significantly related to the size of the first generation, to winter rainfall, which had a positive effect, and to spring rainfall which had a negative effect. These variables accounted for up to 96% of the variation in size of the second generation from year to year. Rainfall and crop hosts were also important for the size of the third generation. The area and tonnage of many potential host crops were significantly correlated with winter rain. When winter rain was omitted from the analysis, the sizes of both the second and third generations could be expressed as a function of the size of the previous generation and of the areas planted to lucerne, sorghum and maize. Lucerne and maize always had positive coefficients and sorghum a negative one. We extended our analysis to catches of H. punctigera (Wallengren), which declines in abundance after the second generation. Winter rain had a positive effect on the sizes of the second and third generations, and rain in spring or early summer had a negative effect. Only the area grown to lucerne had a positive effect on abundance. Forecasts of pest levels from a few months to a few weeks in advance are discussed, along with the improved understanding of the seasonal dynamics of both species and the significance of crops in the management of insecticide resistance for H. armigera.

Deforestation has been linked to a rise in malaria prevalence. In this paper, we studied longitudinally 20 spots, including forested and deforested portions of a temporary river in a malarigenous frontier zone. Larval habitat parameters influencing distribution of Anopheles darlingi (Diptera: Culicidae) larvae were studied. We observed that larvae were clustered in forested-deforested transitions. For the first time in the literature, it was verified that parameters determining larval distribution varied from deforested to forested areas. The proximity to human dwellings was also a significant factor determining distribution, but larvae was most importantly associated with a previously undescribed parameter, the presence of small obstructions to river flow, such as tree trunks within the river channel, which caused pooling of water during the dry season (‘microdams’). In deforested areas, the most important factor determining distribution of larvae was shade (reduced luminance). Larvae were absent in the entire studied area during the wet season and present in most sites during the dry season. During the wet-dry transition, larvae were found sooner in areas with microdams, than in other areas, suggesting that flow obstruction prolongs the breeding season of An. darlingi. Adult mosquito densities and malaria incidence were higher during the dry season. Our data correlate well with the published literature, including the distribution of malaria cases near the forest fringes, and has permitted the creation of a model of An. darlingi breeding, where preference for sites with reduced luminance, human presence and microdams would interact to determine larval distribution.

For the first 150 years following their introduction, eucalypts planted in the California landscape were free of both insect pests and diseases. In the last 15 years, numerous herbivorous insect species have been introduced accidentally into the State and have caused significant damage to the trees. Several of these species, e.g. Phoracantha semipunctata (Fabricius), Phoracantha recurva Newman (Coleoptera: Cerambycidae) and Gonipterus scutellatus Gyllenhal (Coleoptera: Curculionidae), have also been introduced into other parts of the world where eucalypts are grown, whereas others, e.g. Glycaspsis brimblecombei Moore (Hemiptera: Spondyliaspidae) and Eucalyptolyma maideni Froggatt (Hemiptera: Spondyliaspidae), are currently restricted to California and Australia. Research programmes have provided management solutions to individual pest problems, but as more pest species are introduced, these solutions must be integrated across broad geographic, horticultural, and economic scales, in a systems approach.

A convenient and accurate measure of size is necessary for studies on the physiology of tsetse flies (Glossina). Residual dry weight (i.e., dry weight minus fat) is adequate as regards the larva, pupa and teneral fly, but cannot be used for flies that have taken their first blood-meals. A linear measurement provides an index of size that remains constant throughout the life of the fly, but the use of the length of the middle part of the fourth longitudinal vein in the wing has certain disadvantages, and a measure of surface was thought preferable. That finally adopted was a function of the dorsal thoracic surface; details of it are given and a close correlation was demonstrated between it and residual dry weight for females of G. morsitans Westw. bred in the laboratory from puparia maintained at 28°C.

The relation between this measure and the weight of the newly emerged fly is affected by the temperature at which the pupal stage is passed; above approximately 25°C. the surface area of flies of any given residual dry weight decreases quite sharply, so that puparia of a given weight produce smaller but relatively heavier flies at 30 than at 25°C. This holds good also for G. pallidipes Aust. and G. swynnertoni Aust. The dependence of surface area on the temperature at which development has taken place unavoidably complicates the use of this measurement in work on transpiration; it also limits the application of the theory that stresses acting on the pregnant fly may be gauged from the size of flies two months later, and suggests that where the mean temperature of pupal sites is likely to exceed 26°C, any inference should be based on puparial rather than adult size.