The ability to mature eggs without feeding on blood (autogeny), occurring in most populations of Culex tarsalis Coq., approaches an incidence of 50% in the Bakersfield, California strain. Females that were not allowed to lay eggs matured autogenously would occasionally feed on blood but much less readily than anautogenous females. When such females did feed on blood, additional eggs started maturing in other follicles. This produced a heterogeneous assemblage of eggs, some matured autogenously in primary follicles interleaved with others in secondary follicles (on other ovarioles) that matured following the blood-meal. During or soon after autogenous maturation of eggs in some primary follicles, the contemporary primary follicles were resorbed, forming ovariolar dilatations, a condition commonly interpreted as signifying a parous condition.

The egg, five larval instars and pupa of Milionia isodoxa Prout are described, and the adult is redescribed. Setal maps for the first and fifth larval instars are presented.

The development of all stages of Spodoptera littoralis (Boisd.) was studied in controlled-environment cabinets under a range of constant and cycling temperatures. Larvae were tested on three food plants; development was faster on lucerne than on two cultivars of chrysanthemum, Taffeta and Fred Shoesmith. The durations of each instar were similar in relation to larval life span, but at low temperatures and on chrysanthemum many larvae went through an extra instar. Late-instar larvae were nocturnal but larval development was little disturbed by a night-break lighting regime as used in the production of all-the-year-round (AYR) chrysanthemums, and only slightly more so by a reversed temperature cycle. The latter changed the daily pattern of moth emergence which otherwise occurred mostly when temperatures were highest or in the dark. The development results were used to estimate duration of development by summing (a) daily increments of development (100/duration of development), (b) day-degrees (for eggs 28·6 day°C above 14·8°C; for larvae on lucerne 266·1 day°C above 11·5°C, on chrysanthemum 257·1 day°C above 13°C, and above 13°C 177·1 day°C for male pupae and 153·5 day°C for female pupae). The estimates were compared with observed development times for all stages in an environment where temperatures fluctuated naturally. Both methods gave satisfactory estimates when development times were short, but temperature summation was less accurate when maximum temperatures fell close to base temperatures. It is concluded that summation of development increments would give a more consistently accurate account of the life-cycle of S. littoralis on AYR chrysanthemum under glass to enable development to be predicted or past events in the life-cycle to be dated. Tables of development increments against daily maximum and minimum temperatures are given for each stage. To estimate duration of development from these Tables, the daily percentage development corresponding to each day's maximum and minimum temperature is summed up to 100%. This gives an estimate of the median point of hatching or pupation.

Nightly light-trap catches of insects, covering periods of 2–5 years, from two sites in Africa within 10° of the equator are examined in relation to the regular changes in night illumination of the lunar cycle. For several species average log catches at different phases of the moon are almost linearly related to (log) night illumination, catches of some species, such as Isoptera and Bostrychidae, increasing and of others, such as Marasmia trapezalis(Gn.) (Pyralidae), Lampyridae and Dorylus spp. (Formicidae), decreasing with moonlight. Relative catches of M. trapezalis and Bostrychidae varied by a factor of 30:1 between no moon and full moon. Analysis of whole-night catches gives some evidence on the pattern of insect activity through the night, identifying Syntomis monothyris (Hmps.) (Ctenuchidae) and Stemorrhages sericea (Dru.) (Pyralidae) in particular as early morning fliers. Evidence on how night illumination affects catch, and on the times of night when illumination has most effect, is consistent for the two sites and for different years. However, any adjustment of nightly catches to those expected under standard conditions of illumination can only be approximate. Although most of the differences between catches at different moon phases are accounted for by night illumination, many factors influence catch on an individual night, and moonlight is a major factor only for certain species. A hypothesis about how a light-trap may affect insect behaviour allows changes in catch of some species over the lunar cycle to be explained by the influence of background illumination on trap effectiveness.

The biology of Anopheles claviger (Mg.) was studied for a varying number of years in three localities in southern England. The fluctuations in the proportions of the larval instars and pupae were studied by weekly sampling throughout the year. The population overwintered from October to April as pre-adults, and in mid-winter larval development was arrested, but was resumed in March. The construction of a simple life-table showed the existence of a large mortality of immature stages during the overwintering period. Females were sampled at two localities by human bait catches, and at one also by insect suction traps. There was an interval of 1–2 weeks between adult emergences in April and blood-feeding, during which time females apparently fed on sugar solutions. Maximum biting densities of nullipars in May and September showed that A. claviger was bivoltine. The physiological age structure of the population showed that most parous adults at bait had oviposited only once or twice, but a few females had laid four batches. Live Hygrobatid-type mites proved reliable in indicating nulliparity. Mature larvae developed in the eggs 5–7 days after oviposition and while most eggs hatched within the next three days, a few remained unhatched until the 30th day. Females of the second generation (September) laid fewer eggs than those of the first generation (May). About six days were required for blood digestion, and females supplied with sugar were able to live 46 days. The marked delays between successive gonotrophic cycles in natural populations would make parous rates unreliable for the estimation of daily mortalities.

Experiments were done to compare respiration rate, thermal death point, weight loss and the life span of diapause and non-diapause larvae of Busseola fusca (Fuller). The oxygen consumed by non-diapause larvae was 578–772 mm3/g/h while that by diapause larvae was 58–238 mm3/g/h. Thermal death points for both types of larvae were in the range 46·5–49·5 °C. At high and low relative humidities non-diapause larvae lost 4·4% and 16·3% of their weight, respectively, while diapause larvae lost only 1·0% and 7·0%. At 46° and 48°C the percentage weight loss by non-diapause larvae was about twice as much as that by diapause larvae. Life span was greater at a saturation deficit of 14·2–22·5 mm Hg in both types of larvae than either at 2·8–14·2 mm Hg or 22·5–28·0 mm Hg. At this range starving non-diapause larvae lived for 4·3–5·1 days and the diapause larvae for 7·7–8·7 days. The main factor enabling diapause larvae to survive adverse conditions appears to be their efficient water conservation mechanism.

Milionia isodoxa Prout is a serious defoliator of planted hoop pine, Araucaria cunninghamii, in the Highlands of Papua New Guinea. The insect has been found in seven mainland districts, and larvae have been collected from naturally occurring hoop pine in the Madang and Southern Highlands Districts. M. isodoxa is multivoltine, the life-cycle taking approximately eight weeks. The durations of the five larval instars are 4, 4, 4, 5 and 10 days, respectively, and of the pupal period approximately two weeks. The males feed primarily on organic solutes, the females on nectar, so that the sex ratio of adult M. isodoxa in the hoop pine plantations at Bulolo varies with the time of day and locality. Pupae may be attacked by two species of Ichneumonidae and one of Braconidae, and the ants Anoplolepis longipes (Jerd.) and Oecophylla smaragdina (F.) are particularly effective larval predators in the Bulolo plantations; some adults are killed by spiders. The fungus Beauveria bassiana is responsible for high pupal mortality in the Highlands. Frass-drop frequency studies of M. isodoxa larvae in the laboratory showed that feeding activity is greatest in the early instars, and is greater at night for all instars. Larvae reared at 21°C required 14 days more for development than did those reared under the normal daily fluctuation, 19–31°C.

The genus Phytolyma is defined and a key is given to its four species. Two of the species, P. minuta and P. tuberculata, are described as new, another (P. fusca Alibert) is elevated from varietal status and the fourth (P. lata (Walker)) is redescribed. The host-plants are African forest trees, Chlorophora spp. and Morus sp. (Moraceae).

Adults of the cabbage root fly (Erioischia brassicae (Bch.)) reared in culture were inactive on the day of emergence but they fed on carbohydrate (sucrose) and protein (Yeastrel) on day 2. Without food, the egg follicles increased to approximately one-third of their maximum size and were then resorbed. When food was available, females ingested sucrose on days 2 and 3 to mature the first batch of eggs, without any stimulus from mating. Without either a mate or a suitable oviposition site, females retained most of their eggs. Females obtained sufficient food for egg maturation by day 4, when their egg follicles were 400 μm, approximately half the size of the mature eggs. Only females mating on day 4 laid eggs at the expected time 6±0·3 days after emergence. With a suitable oviposition site, these females laid 299±48 eggs, approximately twice as many as any other females, and ten times as many viable eggs. When males were not allowed to mate, peak ingestion was delayed from days 8–12 to days 14–18. Mated females provided with an oviposition site laid most eggs on days 5 and 6 and fed again on day 7. This second peak of feeding was delayed until day 9 when mated females were denied, or unmated females were given, an oviposition site. Similar volumes of sucrose were imbibed by females whether they laid or retained their eggs. Females denied both a mate and a suitable oviposition site laid less than 1% of the expected eggs.

A study, begun in 1966 at Edinburgh University, and completed during the ensuing 30 months at Muguga, Kenya, of the developmental periods of Rhipicephalus appendiculatus Neum. under controlled temperature and humidity was carried out to provide basic background information for an intensified FAO/EAVRO programme of East Coast fever research. Quantitative data are given on the preoviposition, pre-eclosion and, for larvae and nymphs, premoulting periods at three constant temperatures, 25, 21 and 18°C. The rate of development at all stages was accelerated by raising the temperature and retarded by lowering it. A “pre-immobilization period” which precedes the entry of engorged larvae and nymphs to the true moulting process also appeared to be temperature dependent. Development became very prolonged as temperatures fell below 18°C, being negligible at 15°C and having apparently ceased altogether at 9°C. Continuous exposure for more than two or three days to temperatures of 4°C and below were lethal to all engorged instars. Humidity (controlled at levels between 18 and 87% r.h.) had no influence on the rate of development. It is concluded that within limits of tolerable aridity, developmental periods would be completed within the times dictated by temperature regardless of the level of humidity or changes in the level of humidity. No suggestion of any diapause mechanism was discerned.

In experiments with laboratory-maintained colonies of Atta cephalotes (L.) the responses of foraging workers to brood and brood extracts encountered outside the nest were assessed. Ants returned many of the brood to the nest from about one metre, but few from eight metres; any not returned were dumped over the edge of the foraging table. Living and dead pupae were not distinguished by the ants, but to some extent living and dead larvae were. There was some evidence that brood from their own and from other nests were also distinguished. Attempts were made to simulate brood, using extracts and homogenates on filter paper discs, but in no case did the responses suggest that brood pheromones could be used as arrestants in leaf-cutting ant baits.

A new species of Tropiduchidae, Biruga chariclo, is described from adults and nymphs intercepted by the U.S. Department of Agriculture on palm fronds imported from Mexico, and the genus is redefined.

Exitianus occidentalis from rice in Ghana and E. centralis from Uganda and Congo, forming a subgroup with the hitherto unique species E. turneri Ross, are described as new. Comparative illustrations and notes are given for all three species.