The biology and host specificity of Dactynotus chondrillae (Nevsk.) and Chondrillobium blattnyi (Pintera) living on the weed Chondrilla juncea (Compositae, Cichoriaceae) have been studied in the Mediterranean region as part of the biological control programme against this weed for Australia. Both are recorded from south-eastern Russia to the western Mediterranean region. The two species are monoecious. D. chondrillae has a facultative sexual reproductive phase every year but Chondrillobium blattnyi reproduces indefinitely by parthenogenesis in the Mediterranean region. D. chondrillae feeds mostly on young shoots, has population peaks in the spring and in the autumn, and can damage Chondrilla in the field. Chondrillobium blattnyi is a leaf feeder capable of seriously injuring the rosettes, but it never occurs in large enough populations in nature to be damaging. To demonstrate specificity, both aphids were tested against various Cichoriaceae and other Compositae and also against 61 cultivated plant species belonging to 20 families. The two aphids were shown to be specific to the genus Chondrilla. In the laboratory D. chondrillae was less host restricted than the other aphid and it reproduced on Sonchus asper and Taraxacum officinale. Comparative testing with strains of the two aphids from various sources against various forms of C. juncea showed that each strain was adapted to the form of C. juncea occurring in its own geographic area. The southern French strain of these aphids was ill-adapted to the main Australian form of C. juncea, but a strain of D. chondrillae originating from the Italian Adriatic coast heavily infested this form. D. chondrillae was not considered to be specific enough to permit its introduction into Australia and the introduction of Chondrillobium blattnyi has been delayed until it can be shown that it cannot transmit virus diseases that affect lettuce.

Dieldrin, aldrin and γBHC in kerosene were applied topically to adults of Cosmopolites sordidus (Germ.) collected from banana plantations with no history of insecticide application and from plantations that had been treated regularly with dieldrin for many years. Adults from the latter source were highly resistant to dieldrin and aldrin, while resistance to γBHC was lower; those from the former source were susceptible and the results could be used as base line data. Females collected in spring from two untreated plantations showed LD50 values for dieldrin varying by a factor of 1·5, while females collected in the spring were 1·7 times more susceptible than those collected in the autumn from the same plantation. A discriminating dose of 1 μl of 1·0% dieldrin per weevil is considered suitable for detecting resistant individuals.

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.

Young workers, experimentally removed from their nest and set in front of it, are not very good at finding the nest entrance and entering the nest. I examined how young ants learn their nest entrance characteristics, dealing only with the entrance sensu stricto, not with its vicinity. I observed that young ants have the innate behavior of trying to exit and re-enter their nest. I found that they are imprinted with the nest entrance odor while they are still living inside their nest and that they learn the visual aspect of their nest entrances, thanks to operant conditioning, when they exit their nest and succeed in re-entering in the course of their first short trips outside.

During the course of certain investigations, the writer had occasion to collect a considerable number of mosquitoes in Nigeria, particularly in the vicinity of Lagos. Several species of Uranotaenia were represented in many of the collections. In view of the difficulties experienced in identifying certain specimens, opportunity was taken during a recent visit to the British Museum (Natural History) to study the African Uranotaenia in the collections there. Subsequent to the publication by Edwards in 1912 of the last generic treatment and key for the separation of the species, several additional species have been added to the list from the Ethiopian region, and more materials have accumulated, thus facilitating further study and permitting a reconsideration of certain specific assignments.

In working out a collection of Heterocera made by J. D. Bradley in the Solomon Islands, preparations were made of the genitalia of specimens of Spodoptera mauritia (Boisd.) and they were found to differ from those of African specimens, with which they were compared. Subsequent study of the material in the British Museum has shown that two species have been confused under the one name; S. mauritia, which occurs in Madagascar, Mauritius, the Comoro Islands and from India to the Pacific and which is known from continental Africa from only a single female taken at Lindi on the coast of Tanganyika, and the second species, S. triturata (Wlk.), which occurs throughout continental Africa, south of the Sahara Desert. As both species are of economic importance, it has been decided to describe their differences in a separate paper rather than include them in the faunistic paper dealing with the Heterocera of Eennell Island.

The effect of attack by the Coreid bug Pseudotheraptus wayi Brown on the yield of coconut palms was studied in Coast Province, Tanganyika, in 1957–60. Alternate plots in a line of six one-acre plots, each of 50 palms, were sprayed weekly with a mixture containing 0·1 per cent. DDT (to control P. wayi) and 0·1 per cent. malathion (to prevent any increase in scale insects). To facilitate collection of the immature nuts (vidaka) shed by the palms, the plots were kept cleared of surface vegetation. Since this is not a normal practice in local coconut plantations, its effect on yield was checked by leaving the vegetation untouched on six similar, unsprayed, plots immediately adjacent to the first six. All vidaka falling on the latter were collected and recorded daily, and the numbers showing damage by P. wayi were noted. The ripe coconuts on all twelve plots were harvested by climbers, and then counted, at eight-week intervals. Since the nuts take about 12 months to ripen, yields in the first year were in effect those of untreated plots.

The yields from unsprayed plots showed that removing the vegetation was beneficial; the three cleared plots produced 490 and 1,159 more nuts per plot in the second and third years, respectively, than their adjacent, uncleared, partners, whereas in the first year they produced fewer. The mean annual yields from these three cleared but unsprayed plots were successively 817, 2,134 and 3,129 nuts per plot. The corresponding yields from the three cleared plots that were sprayed were 1,102, 3,310 and 2,992. Thus, protection against P. wayi appeared to increase the yield in the second year, but to have no effect in the third, although vidaka damaged by P. wayi were fewer on sprayed plots throughout.

A series of estimates of ‘ total production ’, defined as the sum of the vidaka shed in any period and the ripe nuts subsequently harvested, was obtained by adding the total vidaka collected in successive eight-week periods to the ripe nuts gathered in the harvest taken 11½ months after the middle of each period. These showed that the initially greater yield from sprayed plots came about because a greater proportion of the ‘ total production ’ was converted into ripe nuts, that is, fewer vidaka were shed, doubtless as a result of the diminished attack by P. wayi. The subsequent drop in yield to about the level of the unsprayed plots was due not to any substantial change in this proportion but mainly to a drop in ‘ total production ’.

It is inferred that the number of ripe nuts produced by the palm is subject to an upper limit, which is determined by agronomic factors and greatly exceeded by the number of immature nuts formed. The excess nuts may be shed at an early stage, either for physiological reasons or as a result of biotic factors such as insect attack. Thus there exists a compensating mechanism whereby yields may remain constant under different levels of insect attack and yet show immediate responses to changes in soil or climatic conditions. This could account for the fact that, in the area studied, clearing of plots produced an apparently permanent increase in yield, and insect control only a doubtful and temporary one. It is concluded that, under present conditions, increases in coconut yields are more likely to result from improved methods of cultivation than from pest control with insecticides.

A method was devised for spatial sampling within the soil in potato crops where the soil insects African black beetle, Heteronychus arator (Fabricius) (Coleoptera: Scarabaeidae) and whitefringed weevil, Graphognathus leucoloma (Boheman) (Coleoptera: Curculionidae) are pests. The number and position of potato plant parts, the soil insects, and their attacks on potatoes were defined within the hilled-up soil profile of sections of the planting rows. Neither potato tubers, nor insects nor insect attacks were uniformly distributed. Tubers occurred mainly in the middle of the hill, while the insects contrasted in their distribution in the soil. Most of the damaging H. arator adults and larvae occurred in upper middle areas; the damaging G. leucoloma larvae occurred deeper and were more damaging on the under-side of tubers. The method provides a means of simultaneously sampling soil insect populations in a crop and obtaining a direct assessment of their damage and the effectiveness of control measures.

During the two years that have elapsed since the publication by the writer of a previous paper on Palestine Tabanidae, a small amount of material belonging to this family has been received from the same country. With one exception, for the Diptera in question—which, though few in number, present several points of interest, besides including representatives of two new species—the National Collection is indebted to the kindness of either Mr. P. A. Buxton or Mr. I. Aharoni.

Daily observations were made of the developmental stages of Pachydiplosis oryzae (Wood-Mason) on laboratory-infested IR8 and W1263 rice seedlings at Peradeniya, Ceylon. The previously observed resistance of W1263 was attributed to the inhibition of moulting of first-instar larvae in 40% of the terminal shoot apices. In comparisons of the two varieties, differences in the following parameters were not significant or of no importance: the numbers of P. oryzae eggs laid and their hatching time, the mortality rates of the developmental stages, the number, body length and activity of the larvae and pupae at the terminal apices, and gall length.

Field screening experiments for resistance of faba bean (Vicia faba) to Bruchus dentipes Baudi in Syria between 1982 and 1985 involved about 1000 accessions and indicated that only phenological resistance was present. Two accessions were chosen, on the basis of seed infestation with larvae, for further study. The two accessions (BPL33 and ILB1814) were tested against natural infestations as well as under four levels of bruchid infestation and at two different times of release of adults. BPL 33 maintained its resistance (about 50%) in relation to ILB1814 under these different conditions, except when adults were released at a time when both accessions carried pods simultaneously. This confirms that the resistance of BPL33 was phenological, related to late flowering and late pod setting. An intergrated control approach is there fore suggested.

The new age determination technique for tsetse flies based on the accumulation of fluorescent pigments in the head capsule has the minor problem that it is not possible to accurately identify very young flies. In this paper we describe a technique for the identification of very young Glossina morsitans morsitans Westwood based on their high levels of abdominal fluorescence. Under our holding conditions these fall back in a linear fashion to a minimum at five days post-emergence. The variability in the levels of head fluorescence at eclosion is mainly influenced by the size of the emerging fly, with the number of blood meals taken by the female parent, and intra-uterine larval and puparial periods of the emerging flies also playing a part.

In the laboratory, at a temperature of 30 ± 1°C. and 45 ± 2 per cent, relative humidity, the number of fertile eggs produced by females of Melanoplus sanguinipes (F.) that had copulated once and had then been reared alone in a cage was not significantly smaller than that produced by control pairs of males and females of this grasshopper. The solitary females laid more eggs than did the control females, but the eggs had a significantly lower percentage fertility. They also lived significantly longer, and one female produced eggs over a period of 140 days. Solitary and control females laid the same number of pods per day but the number of eggs per pod gradually decreased after the first two months of egg laying, particularly in the case of the control females, reflecting a decrease with time in the number of functional ovarioles.

Large electrocuting nets were used at different seasons near a big tree in Zimbabwe to capture tsetse flies at different heights, distances from the bole and times of day. Some differences were found between species and sexes, but most flies were caught within 3·3 m of the ground and in the late afternoon. In the cool and wet seasons, Glossina pallidipes Aust. was less confined to lower levels than was G. morsitans morsitans Westw. Flies, especially fed males of G. pallidipes near the bole of the tree, were recorded in the greatest numbers in the midday period. Diurnal variations occurred in the relative proportions of females of the two species caught at different points. Releasing ox odour through an electrocuting net suspended at different heights confirmed that most flies were flying near the ground, especially in the hot dry season. Comparison of samples from the large electrocuting nets with those caught by other methods operated contemporaneously showed that the large nets gave samples which compared well with those from an electrocuting screen used in conjunction with a ventilated pit. Methods involving fly-capture by people gave very distorted results for all catch parameters examined. No method used gave consistently representative samples of replete flies or of newly emerged flies.

Baseline responses of United Kingdom field populations of Macrosiphum euphorbiae (Thomas) and Brevicoryne brassicae (L.) to demeton-S-methyl were investigated using the FAO-recommended dip-test bioassay. Dose-response lines were produced, and discriminating doses for the two species were derived from the results (320 and 500 mg a.i./litre, respectively) and validated by testing further field populations at those single doses. Of the 1620 individuals of M. euphorbiae and 330 of B. brassicae tested, none survived the discriminating doses.

A continuous method is described of separating adult Silvanus surinamensis from infested tea by means of an apparatus involving three behaviour stimuli, namely, light, heat and mechanical activation.

Early in 1959, observations on the farm Tayside, in the East London district of South Africa, suggested that populations of the ‘two-host’ red tick, Rhipicephalns evertsi Neum., were more difficult to control with toxaphene preparations than they had been in the past. Resistance to toxaphene was suspected, and both field and laboratory experiments were carried out to investigate this possibility. Field trials indicated an increase in tolerance by Tayside populations of the tick to toxaphene, γ BHC and dieldrin, but showed no increased tolerance to sodium arsenite or DDT. Similar results were obtained in laboratory experiments where Tayside adults were compared with those of other populations of the tick known to be sensitive to insecticides. Laboratory experiments with larvae indicated a high degree of resistance to toxaphene and γ BHC in the Tayside population, but no increased tolerance to sodium arsenite, Delnav, Sevin or DDT could be detected. This pattern of cross-resistance is similar to that occurring in resistant populations of Boophilus dccoloratus(Koch).

A recent extension of the fly-belt in Songea, southern Tanganyika, has been delimited.

The preferred habitat of the tsetse in this region is constituted by open, short-grassed glades, representing old village sites, in well-grown Brachystegia woodland, with a double-canopied interzone between glade and woodland.

Destruction of this interzone by clearing of the upper canopy will undoubtedly prove effective in causing eradication of the fly.

The identity of the Lymantria species in the north-western Himalayas is confirmed as L. obfuscata Wlk., and not as L. dispar (L.) with which it has commonly been confused in the past. The larval and imaginal characters separating the two species are described and illustrated.

Following the method of procedure already outlined, the life-history of Smynthurus viridis, its bionomics in sensu stricto, and the influence of environmental factors under controlled laboratory conditions, having been considered, the next step is an examination of the seasonal cycle of events as occurring in nature. Part II is, therefore, devoted largely to an analysis of the field data, coupled with an interpretation thereof as substantiated by critically planned and controlled laboratory experimentation; this reinforcement being rendered necessary on account of a multiplicity of factors acting simultaneously in nature. The chief difficulty in an investigation of this kind (as with all problems concerned with fluctuations in the numbers of organisms) lies in the fact that there are few methods for obtaining quickly and easily an accurate quantitative sample of the numbers and kind of organisms; and, secondly, there is the difficulty of finding (in a long-inhabited country like Britain) a “normal” environment, i.e., one in which purely natural agencies have been allowed free play over a sufficient interval of time to allow a state of equilibrium to have become established between the various members of the community to which Smynthurus belongs, in their relationship to the physical factors of the environment and to each other.