Six natural terrestrial mosquito breeding habitats were recognised in the Kano Plains of Kenya by their condition, i.e. temporary or permanent, presence or absence of emergent plants, and by the chemical and physical characteristics of their water. Between September 1968 and March 1970, 13 mosquito species were found breeding in these habitats. Most species were restricted to a few habitats; only four showed a wide occurrence, being found in at least four. Anopheles gambiae Giles and Culex annulioris Theo. exploited all six habitats, suggesting that the characteristics studied were probably not critical to their selection of a breeding site. Mansonia and Coquillettidia spp. were restricted to habitats with some plants, indicating their dependence on such vegetation for respiration and protection. The indiscriminate selection of breeding sites by disease vectors, e.g. A. gambiae, A. pharoensis Theo. and Culex pipiens fatigans Wied., is worth noting in irrigation schemes.

The north-western European species of the laevigatus-group of Apanteles are revised. Forty species are dealt with, of which twenty are described as new. Brief notes are added on North American species of the group in the British Museum (Nat. Hist.) to assist their eventual correlation with the European species.

The genus Subhimalus is erected for the new species S. melanus on potato and S. fuscus on clover; Balclutha versicoloroides from clover is described as new.

To obtain dietary information for the laboratory rearing of Planococcoides njalensis (Laing) the bark tissue of cocoa shoots and mealybug honeydew were analysed for their free sugar and amino acid contents. Paper chromatographic analysis showed the bark tissue to contain mainly sucrose, with smaller amounts of glucose, fructose and raffinose. The proportions of sucrose and glucose+fructose in the honeydew were 24–27% and 24–35%, respectively, with the bulk of the 80% ethanol fraction composed of ketose oligosaccharides. The latter compounds may result from the glycosyltransferase action of mealybug invertase which has been partially characterised. Of the free nitrogenous substances, ethanolamine, asparagine, cysteine, lysine and γ-aminobutyric acid, alanine and glutamic acid are preferentially absorbed. It is concluded that these are important mealybug metabolites, which may be supplied with small amounts of sugar in future liquid-diet trials. Their approximate physiological concentrations were estimated by a semi-quantitative method.

Observations on the sexual behaviour, oviposition and responses to insect prey of the predatory Reduviid Vestula lineaticeps (Sign.) were made in the laboratory. Experiments with cardboard models indicated the importance of moving visual stimuli in eliciting predatory responses, but provided no evidence that olfactory stimuli play any such role. The responses of adult females towards other adults were apparently purely predatory. Males did not visibly discriminate between living females and other specimens (dead females, living or dead males) until they had seized them, when they displayed sexual responses with the living females and usually purely predatory behaviour with the remainder.

A flight mill is described which permits the automatic measurement of flight duration, speed, periodicity and wing-beat frequency.

Fifth-instar nymphs of Rhodnius prolixus Stålwere exposed to the vapours of 11 volatile drugs: acetone, bromobenzene, bromoform, carbon tetrachloride, chloral hydrate, chloroform, dioxane, ethanol, ethyl ether, isopropanol and paraldehyde. Bromobenzene, bromoform, carbon tetrachloride, chloroform and ether induced reversible anaesthesia. For each of these five, the insects exhibited a different andspecific pattern of motor responses before becoming totally immobile; these responses are described. The responses to carbon tetrachloride are similar to the normal feeding responses of this insect. The other six drugs did not induce anaesthesia, but instead, a commonand stereotyped pattern of cleaning responses, suggesting irritation of the sensory organs. It is proposed that the agent-specific responses to the anaesthesiainducing drugs are due to their differential action upon specific portions of the insect central nervous system.

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.

A total of 4418 mosquitoes caught by three collection methods at two levels in the forest near Belém, Brazil, were dissected to determine the proportion of parous individuals. About two-thirds of the mosquitoes belonged to Culex (Melanoconion) portesi Senevet & Abonnenc and C. (M.) taeniopus D. & K. The dissection technique entailed dissecting out the ovaries for examination of the tracheoles, whilst preserving the rest of the mosquito for later processing for virus recovery. Analysis of the results showed that, although significant differences were found in the parous rates from samples caught off human bait, and from mouse-baited Trinidad no. 17 and blower traps, these differences were unlikely to be of practical value when compared to differences in catching ability and ease of operation of the methods. In all, 2771 mosquitoes were classed as parous, and these when inoculated into baby mice in 142 pools yielded 14 isolations. It was concluded that the technique used did not reduce the likelihood of isolating viruses from the dissected mosquitoes.

The feeding penetrations of Myzus persicae (Sulz.) nymphs into tulip leaf epidermis, as shown by a study of stylets and tracks, may be intercellular, intracellular or stomatal with the former predominating. Contact between the stylet sheath or track and cell cytoplasm is at a maximum during intracellular entry but occurs to a limited extent during intercellular penetration due to partial rupture of the epidermal end walls. In the mesophyll, the stylet path is intercellular but a few cells were penetrated by tracks.Tracks vary in appearance according to the degree of confinement to which they have been subjected, the differing amounts of gelling saliva involved beingattributed to alterations in salivation rate or speed of penetration of the bundle. Seventypes of track were recognised, ranging from a thin membraneous to a thick lobular structure. The tracks have recognisable precursors in the stylet sheaths though differences between sheaths and tracks are evident, particularly where saliva is secreted during stylet withdrawal. In the vascular tissues, phloem and xylem are penetrated, often by repeatedlybranched tracks: the point of divergence of the arms of a branched track, in both mesophyll and vascular bundles, occurs only in large inter- or intracellular spaces where the lobular sheath or track is present. Three types of track are common in the vascular tissue:the lobular, the membraneous, and a saliva-filled type. The majority of stylet bundles terminate in the phloem. Rotation of the stylet bundle about its longitudal axis is generally absent.

Neogonatopus brunneicollis reared from Cicadellids in Israel, and Pseudogonatopus saccharivorae from Saccharosydne saccharivora (Westw.) (Delphacidae) in Jamaica, are described as new. N. dimidiatus (Sahlberg) and Gonatopus ruficollis Hellén are redescribed from the holotypes. Descriptive notes are given on two new species of Neogonatopus, parasites of Cicadellids, and one of Pseudogonatopus, parasite of a Delphacid, in Israel.

By means of sticky traps and a suction trap, it was demonstrated on a plot of sugar-cane at Kawanda Research Station, Uganda, that large numbers of crawlers of Aulacaspis tegalensis (Zhnt.) become airborne (up to 10/m3). The numbers increase with wind speed up to about 2·0 m/s and then remain constant, but are depressed by increasing humidity. In laboratory experiments, crawler survival was reduced by high temperatures (30°C) and low humidities (30% r.h.), but some individuals should survive the extreme conditions sometimes experienced if airborne from morning until evening. On hatching, crawlers move upwards and towards the light, but downwards in the dark; movement is inhibited by high humidity. These behaviour responses indicate hat the presence of crawlers in the air is not accidental but a dispersal mechanism. At Arusha Chini, an isolated sugar estate in Tanzania, sticky-trap catches downwind of a windbreak confirmed that airborne dispersal of crawlers is a major source of infestation. It is shown that air currents could have carried crawlers to Arusha Chini from a source on the Kenya coast, 260 km to the east.

During investigations into shoot-fly damage to guinea corn (Sorghum bicolor), millet (Pennisetum typhoides) and maize (Zea mays) in rain-grown plots at Samaru during 1966, it became obvious that attack was not attributable to a single species (Atherigona varia var. soccata Rondani (=A. indica infuscata van Emden)), as was previously believed. This species is undoubtedly the principal pest of guinea corn seedlings and young plants in northern Nigeria (Map 1), but there are also many other species involved. During the following four years field trials were undertaken to establish the relative importance of the species within the area and to learn something of their biology.

A preliminary account of the main differentiating characters of Saissetia miranda(Cockerell & Parrott), S. neglecta De Lotto and S. oleae (Olivier) is given, together with notes on their hosts and distribution in Central and North America. Three forms of S. oleae occur in California.

In arabica coffee estates at Kahuguni and Magogoni, Kenya, female giant looper moths, Ascotis selenaria reciprocaria (Wlk.), rested on coffee tree stems at 60·7 ± 9·8 cm above ground and males at 65·7 ± 6·6 cm; most eggs were laid less than 122 cm above ground. In the laboratory, females laid on average 693 eggs in 5·3 batches; peak oviposition and fertility were 2–3 days after emergence. Life span was 8·3 days for females and 10·4 days for males; at death females contained 1·4 spermatophores each (1·1 in field-collected specimens). It is concluded that hand-picking of moths will have little control value unless done the day after emergence, but that tree-banding with residual insecticide 122–130 cm above ground would kill 90% of the emerging larvae.

Different phosphoglucomutase (PGM) allozymes exist in the three sibling species of theAe. mariae complex. These enzyme variants appear to bedetermined at homologous loci by three codominant alleles designated as PgmA, PgmB andPgmC. Some populations of Ae. zammitii (Theo.) and of Ae. mariae (Ed. & Et. Serg.) were found to be homozygous PgmA / PgmA and PgmB/PgmB, respectively. A laboratory population of Ae. phoeniciae (Coluzzi & Sabatini) was found to be polymorphic for the PgmBand the PgmC alleles, the latter being conspicuously more frequent. An electrophoretically marked PgmC strain of Ae. phoeniciae was easily obtained. This is expected to be useful in release experiments for the study of pre-copulatory isolating mechanisms between this and the other two siblings of the Ae. mariae complex.