The oviposition behaviour of Simulium decorum Wlk., S. vittatum Zett., S. verecundum Stone & Jamnback and S. vernum Macq. is described, with emphasis on the approach by the females to the egglaying sites, the substrates selected and the behaviour of the flies while laying. The eggs and egg-masses of these four species and S. longistylatum Shewell are described; the eggs can be distinguished on the basis of size, and a key is provided to aid their identification. Eggs of S. vittatum completed embryonic development and hatched more quickly than those of S. verecundum of the same age at both 15 and 24°C. The hatch rate of the eggs of both species exceeded 90% when the eggs were present in single-layered masses. The position of an egg Within a multi-layered mass had an important effect on its ability to complete development; significantly lower proportions of eggs of both S. verecundum and S. vittatum in the lowermost layers of large egg-masses hatched, compared with the hatch of those in the top layer. The location of an egg within an egg-mass must be considered a major factor of mortality in the egg stage. The eggs of neither S. verecundum nor S. vittatum were resistant to drying; mortality due to desiccation was related to both the duration of the drying period and the stage of embryonic development when they were subjected to drying.

The rate of development and the egg-production of the Dermestid beetle, Trogoderma parabile Beal, at 30°C. and 60 to 70 per cent. R.H. and the effect upon larval development of the volume of food, the temperature and the relative humidity have been determined.

In 15 to 450 cc. of wheatfeed at 30°C. and 60 to 70 per cent. E.H., active adults are formed from eggs in a mean of 39 days (egg 6, larva 26, pupa 5 and pre-emergence 2). Males develop slightly more rapidly than females. On average, a female adult lives 8 days and 53 of her offspring reach maturity. The weekly rate of increase of a population of stable age distribution (A) is × l·7.

At temperatures between 17·5 and 37·5°C. (and at 70 per cent. R.H.) and at humidities between near 0 and 90 per cent. R.H. (and 30°C.) larvae can grow to a large size; but in 0·7 to 25 cc. of food some of these large larvae enter a facultative diapause, as a result of restricted space. Disturbance of the food increases the proportion of diapause larvae. The diapause larvae feed and moult intermittently. At 30°C. and 60–70 per cent. R.H., a period of seven weeks after hatching has been adopted arbitrarily to distinguish diapause and non-diapause larvae. Only a limited success was obtained in breaking the diapause, which is less readily broken than that of T. granarium Everts.

Rhodnius prolixus Stȧl was successfully reared for three generations on a diet of defibrinated pig blood fed through Parafilm or silicone-rubber membranes. Reproduction in terms of the number and sizes of eggs produced was superior to, while survival from egg to adult was equal to that reported for, insects fed on live hosts. The technique appears equally applicable to the rearing of Panstrongylus megistus (Burm.), Triatoma infestans (Klug) and T. brasiliensis Neiva. The inadequacy of cow blood as a diet for R. prolixus was manifested in a decrease in adult size after two generations and in a reduction of egg weight from 30 to around 16 mg per female per week. This was accompanied by a corresponding reduction in egg hatch from 90 to about 50%.

A general survey of the species of Anopheles in Zaria Province, Northern Nigeria, carried out between June 1957 and December 1958, was designed primarily to ascertain the bionomics of actual and potential vectors of malaria there. The studies, which were centred upon the four principal domestic Anophelines, A. gambiae Giles, A. funestus Giles, A. nili (Theo.) and A. wellcomei Theo., were carried out by making regular floor-sheet collections and entranceand exit-trap catches in native huts, together with biting catches inside and outside huts. Data on other Anophelines and Culicines, taken at the same time, were also recorded.

The studies show that in this region, where malaria is holoendemic, all four species are endophagous to a greater or lesser extent although both A. gambiae and A. nili prefer to feed outside if a host is available. Only two species have been incriminated as vectors, A. gambiae, which had a sporozoite rate of between 4 and 7 per cent., and A. funestus with between 3 and 8 per cent., according to the season.

Collections by floor-sheets and by catches at human bait showed that A. gambiae, A funestus and A. nili were predominantly wet-season species, although in one village area studied A. funestus also occurred in fairly high numbers throughout the dry season. A. wellcomei, on the other hand, was shown to be a predominantly dry-season species.

By using traps and making collections with human bait, the entrance, exit and biting times of A. gambiae, A. funestus and A. nili were ascertained. The largest numbers of A. gambiae and A. funestus entered huts between 9.0 and 11.0 p.m. and left between 3.0 and 5.0 a.m., the maximum biting activity for A. gambiae being between midnight and 5.0 a.m., and for A. funestus between 11.0 p.m. and dawn. A. nili differed considerably from the other two species, having two peaks of maximum entry, between 9.0 and 11.0 p.m. and 1.0 and 3.0 a.m., the period of maximum exodus being between 1.0 and 5.0 a.m., with a peak of biting activity between 10.0 p.m. and 1.0 a.m. It was found that a very high proportion of the mosquitos caught leaving the huts was unfed; between 1.0 and 5.0 a.m., 64 per cent, of A. gambiae leaving, 63 per cent, of A. funestus and 30 per cent, of A. nili were unfed.

Apart from the four domestic species of Anopheles mentioned above, the only other anthropophilous species which could be described as common in the vicinity of Kaduna were A. coustani Lav., A. theileri Edw., A. flavicosta Edw. and A. rufipes (Gough). A. implexus (Theo.) is recorded from Nigeria for the first time.

The commonest species of Culicines taken at human bait during outside night collections were Mansonia africana (Theo.), M. uniformis (Theo.), M. cristata (Theo.), Aëdes lineatopennis (Ludl.) and Culex poicilipes (Theo.). Of these, M. uniformis was by far the most regular and persistent biter throughout the year. M. africana, on the other hand, was only taken in any numbers during October.

In an appendix, a list of 17 species of Anopheles (including 3 varieties), 65 of the CUlicinae and two of the TOxorhynchitinae known to occur in Zaria Province is given, with notes on their distribution and bionomics.

The use of standardised artificial substratum units (SASUs) for sampling preimaginal populations of Simulium is reviewed and the results then given of experiments with SASUs in rivers and artificial streams in West Cameroon in 1968–70. The increase of downstream drift of larvae by night is attributed to the increased activity of associated fauna at night. The numbers of larvae settling on SASUs is partly afunction of how long the latter have been set and partly due to the pattern of fluctuation in river depth. Any particular SASU appears to be selective in relation to the different species of Simulium available for settlement. A new index of uniformity is proposed for comparing the diversity of Simulium faunas occurring on different substrata.

Studies on populations of Zeiraphera diniana (Gn.) in Britain, where the tortricid has recently attained pest status, revealed differences in their structure and host-plant relationships when compared with populations at other European localities. A switch from the predominance of larch (Larix decidua) as a host in alpine Switzerland to pine (Pinus contorta) in upland Britain was governed by temperature which, during the egg stage, altered the phenological relationships between hatching caterpillars and foliage on the two conifers. Larvae which originated from populations on pine had higher survivorship on foliage of spruce (Picea) and larch than populations which originated on larch. Larval age heterogeneity, induced by a prolonged egg hatching period, was a marked feature of British populations and could have significant demographic consequences including an occasional reduction in the degree of temporal separation of racial units at the adult stage. Patterns of polymorphism in larval samples from Pinus contorta and Larix spp. in a variety of forests in Britain gave support to a hypothesis of racial hybridisation at the edge of the insect's range. There were overall differences between colour-type structure of larvae on larch at an English site and at a comparable Swiss locality, and also a similar trend in the change of a colour-type index with changes in population density between years. This suggests that similar selective forces may apply to the population dynamics of Z. diniana throughout its range.

A list is given of all the species of mosquitos so far recorded from the Seychelles, with their distribution in so far as this is known. A number of new records are included based on collections made recently by one of us (E.S.B.).

One species and one subspecies new to science are here described for the first time. The first full descriptions of the male terminalia and pupae of certain other species are included.

Some notes are given regarding the taxonomy, bionomics and local distribution of the species concerned and the zoogeography of the groups to which they belong.

Appendices are devoted to corrections to the second edition of “The Mosquitoes of the Ethiopian Eegion”, Vol. I by G. H. E. Hopkins, and to the mosquitos of other islands in the western Indian Ocean.

To estimate the net effect of climate change on natural populations, we must take into account the positive and negative effects of temperature oscillations and climate variability. Warming because of climate change will likely exceed the physiological optima of tropical insects, which currently live very close to their thermal optima. Tropical insects will be negatively affected if their optima are exceeded otherwise warming may affect them positively. We evaluate the demographic responses of the cowpea aphid, Aphis craccivora, to summer warming in subtropical and tropical Taiwan, and examine the effects of diel temperature oscillation on these responses. Aphids were reared at four temperatures (current summer mean, +1.4, +3.9 and +6.4 °C), the latter three simulating different levels of warming. At each average temperature, aphids experienced constant or oscillating (from −2.9 to +3.6 °C of each mean temperature) regimes. As the simulated summer temperatures increased, so did the negative effects on life-history traits and demographic parameters. Compared with aphids reared in constant temperatures, aphids reared in oscillating temperatures developed more slowly and had a longer mean generation time, but their net reproductive rate was higher. These findings demonstrate that climate warming will affect demographic parameters and life-history traits differentially. Studies that use constant temperatures are unlikely to accurately predict biotic responses to climate change.

The numbers of Glossina pallidipes Aust. and G. morsitans morsitans Westw. flying in and out of a large clearing in Zimbabwe were estimated from catches on unbaited electrified nets placed on the perimeter of the clearing. By estimating the numbers of flies that would encounter visual and olfactory attractants in the middle of the clearing, and from measurements of the numbers caught responding and estimates of the efficiency with which responding flies were caught, it was calculated that 80–100% of flying tsetse responded to stimuli they encountered. The importance of flight as a means of encountering host stimuli in woodland and open areas, and with mobile and stationary baits, is discussed.

Dung from calves treated with synthetic pyrethroids negatively influenced, in varying degrees, survival, reproduction and size of the common dung fly Neomyia cornicina(Fabricius). This was documented in assays where the coprophagous larvae and adults of N. cornicina were exposed to dung collected from calves dosed with topical preparations of deltamethrin, flumethrin, cyfluthrin, and α-cypermethrin. Larval mortality was significantly increased in dung collected up to at least seven days after treatment with deltamethrin, α-cypermethrin and cyfluthrin. Alpha-cypermethrin caused significant mortality of adults allowed to feed on moist dung. Nulliparous flies fed for six days on dung collected three days after treatment of calves with α-cypermethrin or deltamethrin showed little or no ovarian development. A tendency for a comparable effect with flumethrin was also observed. A connection between ovarian development and inhibition of feeding was indicated by the observation of significantly lowered excretion rates in flies exposed to residues of deltamethrin, α-cypermethrin and flumethrin. Larvae that survived exposure to dung from calves dosed with deltamethrin, α-cypermethrin, or cyfluthrin gave rise to smaller flies. The effect on adult fly size decreased when larvae were exposed to dung collected at longer times after treatment of the calves. Adult fly size was significantly reduced in dung collected up to 14 days (α-cypermethrin) or up to 28 days after treatment (deltamethrin and cyfluthrin). Fluctuating asymmetry of a wing vein character did not reflect the anticipated levels of exposure. The study strongly indicated that the use of synthetic pyrethroids affected the insect dung fauna and that such use may reduce dung decomposition.

Some effects of temperature, relative humidity and food supply on the fecundity, length of adult life and rate of development of Necrobia rufipes (Deg.) are outlined.

At 30°C. and 64–70 per cent. R.H., females laid few eggs when supplied with palm kernels as food, whereas when given freshly squashed larvae of Carpophilus dimidiatus (F.) as their only food supply they laid large numbers of eggs.

When Aspergillus spp. commonly found on copra of high moisture content were cultured, conditioned and supplied as the only food at 30°C. and 81 per cent. R.H., newly emerged larvae died within two days. Complete mortality also occurred on palm kernels at 30°C. and 64–70 per cent. R.H., although a few larvae survived for 60 days.

On copra alone, complete development occurred in all conditions attempted, except at 25°C. and 53 per cent. R.H. Development on this food was most rapid at 30°C. and 81 per cent. R.H. (mean period (larva + pupa) 66·5 days). The addition of fishmeal to copra reduced the mean period of development (larva + pupa) at 30°C. and 81 per cent. R.H. to 42·6 days. The shortest mean period of development (larva + pupa) recorded, 37·9 days, was with larvae of C. dimidiatus as food, at 30°C. and 64–70 per cent. R.H. Rapid development was also achieved by adding larvae of N. rufipes to a culture of Oryzaephihis mercator (Fauv.).

Plant characteristics often influence the distribution of herbivores and natural enemies. In turn, the degree of their spatial association is likely to influence the ability of natural enemies to control pests. Also, an understanding of pest distribution patterns is important for the development of reliable and cost-effective sampling protocols. In this study, we assessed the effect of cotton variety and developmental stage on the within-plant distribution and degree of spatial overlap between populations of two thrips species and their predators. In the two studied varieties, cv. Pima and Acala, almost all Thrips tabaci Lindeman inhabited the leaves, while Frankliniella occidentalis (Pergande) colonized only the flowers. With respect to the predators, most Chrysoperla carnea (Stephens) were found on the leaves of both varieties, whereas predatory Orius spp. colonized mainly the flowering structures on Pima plants but the leaves on Acala. This variability in prey and predator distribution resulted in a significant and positive correlation between thrips and predator populations on Pima but not on Acala plants. The results also suggest that, overall, thrips are most likely to be preyed upon on squares and to be relatively safe in flowers. An intermediate but relatively high risk of predation apparently occurs on the leaves. The significance of these within-plant distribution patterns for the monitoring of thrips populations is discussed.

The soybean aphid, Aphis glycines Matsumura, is a recent invasive pest of soybean in North America. Currently, much research is focused on developing and characterizing soybean cultivars expressing host-plant resistance. During the initial phases of host-plant resistance screening, many of these studies use soybean aphid laboratory populations. Previous studies in other systems have documented substantial differences among laboratory and field populations. Whether or not this pattern exists in A. glycines is unknown, but it is extremely important when estimating the level of selection and virulence to host-plant resistant soybeans. In this study, we used seven microsatellite markers to estimate and compare genetic diversity and differentiation among five laboratory and 12 field populations. Our results indicate that soybean aphid laboratory populations are severely lacking in genotypic diversity and show extreme genetic differentiation among each other and to field populations. Continued use of laboratory populations for initial soybean aphid resistance screening could lead to erroneous estimations of the potential success for host-plant resistance.

In this survey of distribution and prevalence of adult ticks (Acarina, Ixodoidea) parasitising domestic animals in the northern regions of the Somali Democratic Republic, 26 species were identified. The ten most common species were widely distributed with Hyalomma anatolicum anatolicum Koch, H. dromedarii Koch, H. erythraeum Tonelli-Rondelli, H. impeltatum Schulze & Schlottke and Rhipicephalus sanguineus group more common in the drier vegetation zones, and H. marginatum rufipes Koch, H. truncatum Koch, R. e. evertsi Neum., R. pravus Dön. and R. pulchellus (Gerst.) more common in the wetter woodland, evergreen and forested zones. Four species, Amblyomma gemma Dön., A. variegatum (F.), Boophilus decoloratus Koch and R. simus Koch, were confined to the wooded zones above 1200 m altitude. Species collected less frequently were Argas persicus (Oken), Amblyomma falsomarmoreum Tonelli-Rondelli, H. anatolicum excavatum Koch, H. m. marginatum Koch, H. m. turanicum Pom., H. punt Hoogst., Kaiser & Pedersen, Ornithodoros savignyi (Aud.), R. armatus Pocock and R. longicoxatus Neum. Ambylomma lepidum Dön. was represented only by a few specimens introduced on nomadic livestock.

Nearly 60% of the total number of ticks collected were R. pulchellus. This species is considered to be the main vector of Nairobi sheep disease (NSD) virus in northern Somalia. NSD is the most important tickborne disease in sheep and goats and causes considerable economic losses to the Somali livestock industry. A. gemma and A. variegatum are probably the vectors of Cowdria ruminantium (heartwater) in sheep and goats in the western highlands. These two ticks are also incriminated in the spread of Dermatophilus congolensis infection (streptothricosis). R. e. evertsi may be the vector of Babesia motasi in sheep and goats. Boophilus decoloratus is probably the vector of Babesia bigemina in cattle in the western highlands. Various tick species may be associated with bacterial abscesses of feet and lymph nodes in sheep and goats.

Dacus dorsalis Hend. infested eleven, D. cucurbitae Coq. five and D. umbrosus F. two of the eighteen common fruits and vegetables grown in Penang, West Malaysia. D. tau (Wlk.) infested bacang (Mangifera foetida), D. caudatus F. chilli (Capsicum annuum) and D. frauenfeldi Schin. water guava (Eugenia javanica), together with D. dorsalis. Pomelo (Citrus grandis) was found infested for the first time by D. cucurbitae. No flies were trapped using Capilure and trimedlure as baits. Cue-lure attracted D. caudatus, D. cucurbitae, D. frauenfeldi, D. occipitalis (Bez.) and D. tau. Methyl eugenol attracted D. dorsalis and D. umbrosus. Dorsalure was less attractive to D. caudatus and D. dorsalis than cue-lure and methyl eugenol, respectively, but it was equally attractive to D. frauenfeldi as cue-lure. Using traps baited with cue-lure or methyl eugenol in five ecosystems, the highest numbers of males of D. dorsalis, D. umbrosus, D. frauenfeldi and D. caudatus trapped were from a village, on a vegetable farm for D. cucurbitae, and D. occipitalis was only caught in a forest. Analysis showed that for each species of Dacus the difference between ecosystems was highly significant. The few examples caught in grassland were probably migrants.

Sir Rickard Christophers (1947) working at 25°C. and a relative humidity of 80–90 per cent. found female Aëdes aegypti to be attracted by a warm dry surface at 40°C., and to be unaffected by a moist surface at room temperature. The writer (1948), working at 28°C. and 50–70 per cent. R.H. (usually near 50 per cent.) found the opposite: a warm dry surface at temperatures from 36°C. to 40°C. had no effect, while a moist surface at room temperature exerted a quite definite attraction. The purpose of the present experiments was to test the hypothesis that the difference between the results obtained in these two investigations was due to the difference in the ambient temperature and humidity.

Repetition of the relevant experiments at 25°C, 85–90 per cent. R.H., and 28°C, 50–55 per cent. R.H., gave results indicating that temperature and humidity difference operating at the time of the experiment could account for part but not all of the discrepancy. There are indications that the remainder may have been a result of the conditioning effect of temperature and humidity differences operating on the insect prior to the experiment.

The results emphasise the need for a full description of the climatic conditions under which behaviour work of the type discussed is performed.

Monitoring saproxylic beetle diversity, though challenging, can help identifying relevant conservation sites or key drivers of forest biodiversity, and assessing the impact of forestry practices on biodiversity. Unfortunately, monitoring species assemblages is costly, mainly due to the time spent on identification. Excluding families which are rich in specimens and species but are difficult to identify is a frequent procedure used in ecological entomology to reduce the identification cost. The Staphylinidae (rove beetle) family is both one of the most frequently excluded and one of the most species-rich saproxylic beetle families. Using a large-scale beetle and environmental dataset from 238 beech stands across Europe, we evaluated the effects of staphylinid exclusion on results in ecological forest studies. Simplified staphylinid-excluded assemblages were found to be relevant surrogates for whole assemblages. The species richness and composition of saproxylic beetle assemblages both with and without staphylinids responded congruently to landscape, climatic and stand gradients, even when the assemblages included a high proportion of staphylinid species. At both local and regional scales, the species richness as well as the species composition of staphylinid-included and staphylinid-excluded assemblages were highly positively correlated. Ranking of sites according to their biodiversity level, which either included or excluded Staphylinidae in species richness, also gave congruent results. From our results, species assemblages omitting staphylinids can be taken as efficient surrogates for complete assemblages in large scale biodiversity monitoring studies.

An account is given of an investigation made of the life-histories of Oscinella frit and its parasites in Ontario, Canada, with a view to the possible introduction of suitable parasites into England. The various Chloropid species associated with O. frit in North America are discussed.

The life-history of the frit-fly in Ontario is similar to that in England except wheat, not oats, is attacked, and that there appears to be no regular grain-infesting generation, but the insect is never a major pest in Canada.

The life-histories of the following six species of parasites are described : Hexacola sp. n., Polyscelis sp. n., Loxotropa sp., Cyrtogaster sp., Callitula bicolor and Spalangia drosophilae. Other hosts from which these parasites have been reared include Chloropids associated with O. frit in wheat, namely O. carbonaria, O. soror, O. minor and Meromyza americana.

A brief account is given of the control exerted by these parasites on the population of frit-fly in Ontario and a comparison is made between the Canadian and English parasite complexes. From this it is concluded that S. drosophilae might exert some control of frit-fly if introduced into England.

Cosmopolitan pests such as Brevicoryne brassicae, Lipaphis pseudobrassicae, and Myzus persicae (Aphididae) cause significant damage to Brassicaceae crops. Assessment of the important biotic and abiotic factors that regulate these pests is an essential step in the development of effective Integrated Pest Management programs for these aphids. This study evaluated the influence of leaf position, precipitation, temperature, and parasitism on populations of L. pseudobrassicae, M. persicae, and B. brassicae in collard greens fields in the Triângulo Mineiro region (Minas Gerais state), Brazil. Similar numbers of B. brassicae were found on all parts of the collard green plants, whereas M. persicae and L. pseudobrassicae were found in greatest numbers on the middle and lower parts of the plant. While temperature and precipitation were positively related to aphid population size, their effects were not accumulative, as indicated by a negative interaction term. Although Diaeretiella rapae was the main parasitoid of these aphids, hyperparasitism was dominant; the main hyperparasitoid species recovered from plant samples was Alloxysta fuscicornis. Parasitoids seem to have similar distributions on plants as their hosts. These results may help predict aphid outbreaks and gives clues for specific intra-plant locations when searching for and monitoring aphid populations.

Widespread slight pyrethroid-resistance in Musca domestica L. on animal farms in southern England was correlated with strong resistance to trichlorphon and to malathion, and with the presence of an esterase, E0·39, detected by electrophoresis. In the laboratory, the frequency of E0·39 increased in response to selection with either pyrethroids or trichlorphon. Genetic analysis confirmed that this esterase, controlled by a gene on autosome 2, was closely linked with moderate resistance to trichlorphon and malathion and weak resistance to pyrethroids. When autosome 2 with the gene for E0·39 was introduced into a strain homozygous for the resistance mechanism super-kdr, resistance to pyrethroids increased by a factor equivalent to the weak resistance conferred by autosome 2 with E0·39 alone. Homozygosity for both mechanisms of resistance, and E0·39, was obtained by selecting the progeny of this cross with permethrin alone, permethrin and trichlorphon, or DDT and trichlorphon, demonstrating that very strong pyrethroid resistance can be achieved through the use of non-pyrethroid insecticides. E0·39 was absent from insecticide-resistant strains of M. domestica from Denmark but was present in several multi-resistant strains from other European countries.